This document provides an overview of meat hygiene and quality assurance. It discusses the importance of meat hygiene in ensuring meat safety and suitability for human consumption. Good agricultural practices, good hygiene practices, and hazard analysis and critical control points are described as key components of a meat quality assurance system. Guidelines are provided for maintaining hygiene at various stages of meat production including on farms, during transport, slaughter, processing, and storage.

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UNIVERSITY OF NAIROBI
DEPARTMENT OF PUBLI HEALTH, PHARMACOLOGY AND TOXICOLOGY
FACULTY OF VETERINARY MEDICINE
CERTIFICATE IN MEAT HYGIENE AND QUALITY ASSURANCE
Course Unit
MEAT HYGIENE AND QUALITY ASSURANCE
(Lecture notes - January 2013)

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MEAT HYGIENE AND QUALITY ASSURANCE
Meat hygiene can be defined as the creation of conditions and implementation of
measures necessary to ensure the safety and suitability of meat at all stages of the
meat production chain. Meat safety is the assurance that meat will not cause harm to
the consumer when it is prepared and or eaten according to its intended use. Meat
suitability is the assurance that meat is acceptable (in terms of taste, smell and
nutritional state) for human consumption. Effective hygiene control is vital to avoid the
adverse human health and economic consequences of unsuitable meat and meat
related illnesses. Everyone including farmers, processors and regulators have a
responsibility to assure consumers that meat is safe and suitable for consumption.
The main objectives of Meat hygiene and quality assurance are to:
1. Safeguard the health of the people through production, distribution and
consumption of safe meat;
2. Promote national and international trade of meat;
3. Prevent avoidable meat losses and promote conservation of livestock resources.
Scope of meat hygiene
Meat hygiene programs are aimed at controlling the hygienic standards of the meat at
all levels of meat production chain. This include monitoring the quality of animals being
raised for meat production, their disease status and nutrition level, handling during
transportation to and at the slaughterhouses, methods of slaughter, ensuring thorough
ante-mortem and postmortem inspection, hygienic transportation of meat to butcheries
and/or markets, as well as ensuring the hygienic state of the butcheries and meat
markets, storage conditions before they reach the consumer. In particular, efforts are
directed at prevention of animal diseases at the farm, prudent use of veterinary
medications and other chemicals in food animals and observing the recommended
withdrawal periods, prevention of diseased animals and those under treatment from
getting to the slaughterhouse, ensuring hygienic slaughter of animals and prevention of
contamination of meat from slaughter animals, slaughter personnel, water, vermin
(rodents flies and other insects), equipment and general environment. In addition, there
is need to prevent meat deterioration and spoilage through appropriate measures which
may include controlling temperatures, humidity and or other controls.
Importance of Meat hygiene
1. Prevention of food borne disease outbreaks. Food borne diseases leads to
consumer suffering and loss of life.
2. Prevents meat deterioration that may lead to unnecessary losses
3. Enhances local and international trade in meat due to enhanced consumer
confidence
4. Creates employment as more income is realized from sale of meat.

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Meat Quality Assurance
Meat quality Assurance is the systematic implementation of planned meat hygiene
measures along the meat production chain to provide adequate confidence to the
consumers that meat is safe for their consumption. Meat Quality assurance systems are
a set of regulatory and non-regulatory institutions involved in activities aimed at
ensuring the safety of meat. It includes the official mandatory regulatory activities
enforced by national and local authorities to provide consumer protection and ensure
that meat is safe, wholesome and fit for human consumption.
Meat quality assurance system focuses on hazard prevention, elimination, control or
reduction of hazards to acceptable levels throughout the meat production chain. A
hazard is a biological, chemical or physical agent in food with a potential to cause an
adverse health effect. There are three types of hazards that may be found in meat
1. Biological hazards: which are microorganisms (bacteria, viruses, yeast and
molds) and their toxins that may be found in food
2. Chemical hazards e.g. cleaning chemicals, pesticides, drug residues, heavy
metals, allergens etc.
3. Physical hazards e.g. foreign bodies such as stone, mud, glass, plastics and
metals.
Food hazards are the cause of meat borne diseases that leads to consumer suffering
and loss of life. Food borne diseases are diseases that are transmitted to humans
through consumption of a disease agent (hazard) in the meat. Considerable costs arise
due to associated medical treatment, lost production, recalls and disposal of faulty
products. Outbreaks of meat borne diseases often result in bad publicity, loss of market
for the meat product, and may lead to legal costs related to illness or loss of life.
Meat quality assurance system approach is based on the application of Good
Agriculture Practices (GAP), Good Hygiene Practices (GHP), Good Manufacturing
Practices (GMP), Sanitary Standard Operating Procedures (SSOP), Hazard Analysis
Critical Control Point (HACCP) system, food safety management systems and
traceability/recall systems. The GAP, GHP, GMP and SSOP are considered as
prerequisite systems or programs for implementation of the HACCP system. The
HACCP system for production of meat is a proactive means of controlling production
processes aimed at enhancing the safety of meat.
The GAP, GHP, SSOP are measures that are required to produce safe food. The GAPs
are basic food safety principles associated with minimizing biological, chemical and
physical hazards at primary production stages.

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GAPs related to animal production, health and welfare
Good Agricultural Practices are a collection of principles to apply for on-farm production
and post-production processes, resulting in safe and healthy animal food products and
non-food agricultural products, while taking into account economical, social and
environmental sustainability: Good Agricultural practices therefore include:
 Provide animals with adequate and suitable feed, clean water and appropriate
housing conditions that protect them from adverse weather conditions.
 Prevent outbreak of disease epidemics through regular vaccination programs.
 Alleviate pain in sick animals through provision of appropriate treatment
 Design, construct and use and maintain equipment and handling facilities to
avoid injury and loss.
 Avoid non-therapeutic mutilations, surgical or invasive procedures, such as tail
docking and de-beaking;
 Manage stocking rates to avoid overstocking and the associated negative
impacts on landscape, environment and life:
 Avoiding biological, chemical and physical contamination of land for grazing,
pastures feeds, water and air
 Prevent chemical and veterinary drug residues from entering the food chain
 Minimize non-therapeutic use of antibiotics or hormones
 Avoid feeding animals with animal wastes or animal matter in order to reducing
the risk of alien viral or transgenic genes, or prions such as mad cow disease),
 Minimize transport of live animals (by foot, rail or road) to reducing the risk of
epidemics, e.g. FMD
 Purchase, store and use only approved veterinary products in accordance with
regulations and directions including withholding periods.
 Use methods of pre-slaughter handling and slaughter that are humane and
appropriate for each species.
 Use of appropriate records and traceability methods on the whole production
chain (breeding, feed, medical treatment...) to ensure consumer security and
feedback possibility in case of a food crisis
Good Hygiene practices (GHPs)
Good Hygiene Practices are the conditions and measures necessary to ensure the
safety and suitability of food at all stages of the food chain. They are hygienic rules
translated to work instructions and procedures for employees and machinery
operations.. The GHPs require that all persons working in direct contact with meat, meat
contact surfaces and meat packaging materials conform to sanitation and hygienic
practices and standards to the extent necessary to protect against contamination of
meat from direct or indirect sources. One of the elements of GHPs is that meat
businesses assess their own standards and make decisions regarding the practices and
procedures which ensure good hygiene practices.

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Good hygiene practices at various stages of meat value chain
At farm level:
 Keep animals free of diseases through regular vaccination and treatment.
 Prevent accumulation of chemical and veterinary drug residues in animal tissues
by feed animals with clean feed and prudent use of veterinary drugs.
Lairage: The principal function of the lairage is to provide a reservoir of animals for the
slaughter. For the purposes of food safety, and on animal welfare grounds,
 Facilities must be available for the isolation and removal of any animals showing
signs of illness.
 Pressurized water is preferred to wash animals prior to slaughter
 Animals must be adequately rested before slaughter for 12hrs.
 Food should be withheld12hrs before slaughter.
 Anti-mortem inspection must be diligently carried out to detect sick animals.
Many diseases are often more easy to detect during Am rather than pm
Slaughter and flaying process
• Slaughtering should be done in tables or in hanging rail to reduce contamination
by regurgitation
• The slaughtering knife should be cleaned and sterilized between each carcass at
82°C.
• The head should be removed and after skinning washed separately from the
carcass.
• Tonsils should be removed cleanly as they are heavily contaminated with
pathogenic bacteria.
• During dressing the oesophagus of slaughter animals should be tied to prevent
leakage of ruminal contents.
• Removal of hides or fleece should be carried out so that contact between the
outside of the skin and the carcass is avoided while hands and equipment that
touch the outside of the skin should not come into contact with the underlying
carcass meat.

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• After the initial cut through the skin, sterilize the knife in water at 82°c and then
make all other cuts from the inside out.
• No hair or skin pieces should be left on the skinned carcass.
• No excess blood should appear on the skin of the carcass.
• Prevent contact of dirt from hides and skin to the meat surface.
• Prevent contamination of the carcass with dirty hooks, knives and protective
clothes.
GHP during Evisceration
• It is recommended that a plastic bag is used to seal off the rectum after
loosening; this is sometimes referred to as ‘bagging’.
• Do not puncture the viscera (alimentary tract), uterus, urinary bladder and gall
bladder during separation cuts.
• Prevent contact of viscera with floors, walls or stands.
• Regularly wash hands/aprons and sterilize knives, especially after any possible
contamination has occurred.
• Identify/correlate viscera with the related carcasses
• Careless evisceration must be avoided to prevent contamination of the carcass
with gut contents.
Carcass splitting
• Carcass splitting saws should be sterilized between each carcass.
Carcass washing
• Carcases should be washed after spliting using cold potable water
Post-mortem inspection
• During post-mortem meat inspection, palpation and incision of lymph nodes,
infected tissues or tissues with abnormalities can give rise to cross
contamination.
• Incision should be avoided where possible, and palpation of organs should be
minimal.
Personal Hygiene of slaughterhouse workers
 Appropriate protective clothing should be worn and replaced each day or when
heavily soiled. All meat handlers and persons in a room handling meat should

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wear protective clothing’s (overcoat, cap, plastic apron, and gumboots). They
should be of light color, preferably white and be clean and tidy.
 Hands and arms should be washed and knives and equipments regularly
sterilized.
 Workers must wash their bodies regularly and have the nails trimmed as much
as possible. They should not move from dirty to clean areas, but vice versa.
 Nail polish and dyes on nails and hands should be discouraged.
 Beards should be shaven or covered by a turban.
 The hair should be short, clean and tidy. The hair should either completely
covered with a clean cap or hat or confined by a hairnet to prevent hair falling
into products
 Ornaments such as rings watches and bungles should be removed.
 The following must be avoided: heavy perfumes, use of lipstick, false eyebrows
and eye shadows.
 premises indicate that hygiene is not of high standard.
 Washing facilities should be provided where workers can wash before leaving
and a canteen where they could take refreshment and rest during breaks.
Figure 4.9: Slaughterhouse workers dressed in their protective clothing. The cleanliness
of personnel and the external environment of the slaughterhouse is satisfactory.
Medical fitness of meat handlers

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Meat handlers include slaughterhouse staff involved in all stages of slaughter, loading
and transportation of meat, washing and cleaning of equipment and all slaughterhouse
premises and meat retailers.
(a) A meat handler must be healthy and free from communicable disease e.g.
tuberculosis and salmonellosis.
(b) They must go for medical check-ups after every 6 months
Personnel suffering from boils, nose or throat infections, intestinal disorder (diarrhea)
should not handle meat. Their health status will have an impact on the level of bacterial
contamination of meat and this can spread infection to the whole community. Cuts and
wounds should be dressed up nicely. Dressings on hands must have a waterproof
covering to prevent anything passing through the bandages from the wound. Bacteria
from a wound could easily pass through a bandage.
Slaughterhouse cleaning after slaughter operations
• Proper cleaning and sanitation of the slaughter floor, walls and equipment should
occur daily and frequently during the day to reduce contamination from these
sources and it should be done under skillful and firm supervision.
• Sanitary Standard operation procedures (SSOPs) for cleaning and sanitation of
all parts of the plant should be in-place and well-implemented.
Cold storage of meat
• Move the carcasses into the cooler as soon as possible to speed up the surface
drying and hinder bacterial growth.
• Keep carcasses on rails and without touching floors/walls and other carcasses to
prevent cross-contamination.
• Keep carcasses spaced to allow surface drying limits growth of microorganisms.
• Do not overload the coolers.
• Adjust the cooling régime optimally in terms of air temp., speed and relative
humidity, to achieve rapid refrigeration to a deep muscle temperature of 6-7°C
with no condensation or weight loss.
• Do not open the cooler doors either unnecessary or frequently to avoid
temperature fluctuations.
• It is of extreme necessity that adequate lightening should be maintained inside
the cold rooms

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Personnel Education/Training
Slaughterhouse staff should be made fully aware of and conversant with the need for
occupational hygiene, not only to avoid infection and meat contamination but also from
becoming carriers of infection to their families and communities. Education on good
standards of health and hygiene and its importance is essential. Staff should be
educated on:
(a) Hygienic slaughter e.g. using only properly washed and sterilized equipments
e.g. knives, pangas, axes, saws.
(b) Maintaining their own personal hygiene, cleanliness of the slaughterhouse
and slaughter equipment and the environment.
(c) Thorough washing of hands with soap after visiting toilet, coughing or
sneezing, handling of money,
(d) Proper and hygienic disposal of garbage, soiled or infected material.
(e) Knowledge that negligence may be detrimental to the whole community.
(f) How and why unsanitary practices should be avoided.
Sources of carcass contamination before and during slaughter
1. Contamination a farm level (infection and used of drugs and pesticides in animal
husbandry)
2. Dirty feet, hides and skin due to dirty lairages or trekking routes
3. Butchers tools (knives, pangas, axes etc), hands and clothing which are
contaminated. Butchers should continuously wash and disinfect their tools and

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hands during the slaughter operations. They should wear clean gum booths and
dust coats.
4. Flaying: Hides and skin contain high microbial load. Before slaughter, animals
can pass though a warm shower as they head to the stunning box. In addition
care should be taken to ensure clean flaying operations.
5. Intestinal and stomach content during evisceration. Care should be taken to
avoid puncturing and spilling stomach and intestinal contents during evisceration.
In case a puncture occurs, the spilled contents should be washed off immediately
and knife and hands washed disinfected before proceeding with the operations.
6. Poor quality water used to was carcasses
7. Poor personnel hygiene and habits
8. Contaminated meat carriers
9. Meat loading, transporting and cutting;
10. Dogs, birds and vermin(rodents and insects),
Personnel should be taught to avoid the following unsanitary practices (or bad habits)
 Walking aimlessly while operations are going on
 Unguarded coughing and sneezing which can spread pathogenic respiratory
bacteria:
 Spitting on hands to enable firm gripping of an axe, panga e.g. while splitting
carcass
 Licking of fingers to pick up items e.g. papers, utensils, paper towels or wrapping
papers or to turn over the pages of a book
 Cutting of finger nails using teeth or by using slaughter or meat inspection knife
 Placing the pen, fingers in the mouth
 Any contact with saliva will transfer salivary bacteria to the hands or fingers
 Blowing paper bags to open them
 Shaking of hands in the slaughterhouse
 Eating, Smoking of cigarettes, chewing miraa in the slaughterhouse
 Unnecessary touching of meat and placing of meat on dirty places
 Chewing sweet-gum
 Blowing or wiping of nose using bare hands or protective clothing
 Use of mobile telephones
 Nose picking (removal of dried mucus from nostrils) placing fingers in or around
the nose, mouth etc removal of ear wax using fingers, keys, pen, match stick and
then rubbing it on the hands or protective clothing
 Scratching of head
 Brushing of teeth,
 Urinating in undesignated places within the slaughterhouse environment
 Changing of clothes near meat

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 Confrontations, fighting, playing in the slaughterhouse
 Placing meat, knives, sharpening steel in the gumboots
 Washing the apron and protective clothing on the slaughterhouse floor.
SANITARY STANDARD OPERATING PROCEDURES (SSOPS)
SSOPs describe how GHP is to be achieved i.e. minimizing microbial, chemical and
physical contamination. The objective of SSOPs is to prevent contamination of
carcasses and other food products resulting from employee actions during slaughter
and meat processing.
MODEL SANITARY STANDARD OPERATING PROCEDURES (SSOPS)
Sanitary Standard Operating practices to be followed by all employees
1. No person with illness, or open/infected wounds is allowed to handle foods or
food-contact surfaces.
2. All employees must begin their shift wearing clean garments. Raw product
processing employees must wear hair covers and change or clean/sanitize (or
replace) outer garments when they become soiled. Ready-To-Eat (RTE) product
processing employees must wear hair covers and single-use disposable gloves,
and maintain the cleanliness of all outer garments.
3. Employees must wash hands properly after using the bathroom or handling any
objects that may contaminate products, and before putting on disposable gloves.
4. Employees must not use tobacco, eat, or drink in slaughter or production areas.
5. Employees must not wear jewelry (other than secured wedding bands) or
cosmetic items that could contaminate product.
6. Food, beverages, and medications must be stored in designated employee
locker or storage areas.
7. Hand wash facilities and toilets must be kept functioning correctly and properly
supplied.
Sanitary Standard Operating Practices to be specifically followed during
slaughter
Carcass dressing must be performed under sanitary conditions and in a manner to
prevent contamination of the carcass. The Slaughter Manager is responsible for
ensuring that employee hygiene practices, sanitary conditions and cleaning procedures
are maintained during the slaughter day. He or she must make a visual observation at
least once between each break in work (start, break, lunch, etc.) and record his
observations on the SSOP Inspection form at least once per slaughter day.
The following SSOPs are important during slaughter:
a. Clean hands, arms, gloves, aprons, boots, etc., as often as necessary during the
dressing procedures.

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b. Clean and then sanitize (with 180ºF water or another approved sanitizer), knives
and other hand tools, saws and other equipment, as often as necessary during the
dressing procedures to prevent contamination of the skinned carcass.
c. Before using the brisket saw, rinse it to remove meat and bone particles. Then
sanitize it using 180° F water or another approved sanitizer.
d. Keep your hands, arms, clothes, aprons, boots and knives clean during the
evisceration process. If contamination occurs, step away from the evisceration area
to clean apron, boots, and knives. Sanitize knives after cleaning. It may also be
necessary to clean hands and arms with soap and water. In cases of contamination
from an abscess or other extensive contamination, you may need to shower and
change clothes before going back to work.
e. If you see any edible product that is contaminated with readily identifiable Specified
Risk Material (SRM), remove it by trimming with a knife. SRM’s are the distal ileum
and tonsils of all cattle and the brain, skull, eyes, trigeminal ganglia, spinal cord,
vertebral column (excluding the vertebrae of the tail, the transverse processes of the
thoracic and lumbar vertebrae and the wings of the sacrum) and the dorsal root
ganglia of cattle 30 months of age and older. The knife you use MUST be cleaned
and sanitized before it is used again on edible product.
f. Clean and sanitize (using a designated approved chemical sanitizer or 180ºF water)
the carcass splitting saw after it is used on a suspect carcass or when contamination
occurs. NOTE: cleaning off tissue debris and sanitizing the splitting saw are
MANDATORY when moving to a beef carcass that is younger than 30 months after
splitting a beef carcass that is 30 months or older.
g. When equipment is visibly contaminated, remove the contaminants and sanitize
the affected equipment before re-starting production. Inspect the carcass (es) to
determine if they were contaminated or adulterated.
h. Try to determine the cause of the contamination and take corrective action. This
may require adjusting equipment, retraining employees, temporarily stopping the
kill process, etc.
Role of government in quality assurance of meat
The Government through the veterinary authorities is obligated to:
a. Control the registration and use of veterinary drugs, pesticides and feedstuffs so
that residues do not occur in meat at unsafe levels that make the meat or its
products unsafe for human consumption;

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b. Control animal and zoonotic diseases in livestock meat for slaughter through
vaccinations, animal treatment.
c. Provide and enforce monitoring and surveillance systems that establish baseline
data of livestock diseases and levels of harmful chemical residue;
d. Take such other measures from time to time that will ensure production of safe
meat and meat products (e.g. control of livestock movements, certification of
slaughter facilities, provision of livestock and meat inspection services, control of
meat transport activities, hygiene of meat transport carriers, control of the
hygiene of meat markets).
Role of Meat Inspectors in Quality assurance of meat
The Veterinary Meat Inspector shall ensure that:-
a. All animals brought to the slaughterhouse are accompanied by a movement
permit indicating the origin, species, number of animals and mode of transport
used
b. a thorough ante-mortem inspection is done to all animals
c. Animals presented for slaughter are sufficiently and thoroughly cleaned before
slaughter in order not to compromise hygienic slaughter and dressing;
d. The animals are held under conditions that minimize cross-contamination with
food-borne pathogens and facilitate efficient slaughter and dressing;
e. The animals are subjected to ante-mortem inspection;
f. Enough facilities for ante-mortem and post-mortem inspection.
g. The slaughter facilities are hygienic and fully prepared for the slaughter.
h. All slaughter and carcass dressing operations as well as any further meat
handling at the slaughterhouse are carried out in a hygienic manner
i. Any information gathered during ante-mortem inspection which is considered
appropriate for the producer for future or immediate action is sent to him in
reasonable time;

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FOOD BORNE DISEASES
Food borne diseases are diseases that are transmitted to humans through
consumption of a disease agent in the food. Food borne diseases are
classified into two categories
1. Food borne infections
2. Food borne intoxications.
Foodborne infections are caused by the entrance of pathogenic
microorganisms contaminating food into the body, and the reaction of the
body tissues to their presence. These can either be fungal, bacterial, viral or
parasitic. Bacterial food borne infections are the most common. Food borne
infections tend to have long incubation periods and are usually characterized
by fever. They include bacterial (salmonellosis, cholera, typhoid fever,
shigellosis, Yersinia enterocolitica infection, E. coli infections,
campylobacteriosis, Listeria monocytogenese, mycotic (Candida spp.,
Sporothrix spp., Wangiella spp. etc), viral (hepatitis A and poliomyelitis),
parasitic infections (hookworms, roundworms and tapeworms) and
protozoan (balantidiasis, amoebiasis etc)..
Salmonellosis
The salmonellae organisms are capable of causing disease in animals and
man when taken into the body in sufficient numbers. The salmonella species
involved in food poisoning include; Salmonella typhimurium, Salmonella
enteritidis, Salmonella dublin, Salmonella softenburg, Salmonella virchow,
Salmonella montevideo, Salmonella infantis, and salmonella newport. These
species are also involved in causing diarrhea in animals. In some cases, they
are nosocomially transmitted between people in hospitals.
Clinical signs in man
Salmonella food poisoning is characterized by symptoms which appear 12
hours after consumption of food. The illness is due to the growth of the
organisms within the body. The ordinary symptoms are abdominal pain
diarrhea, chills, fever, vomiting, headache, prostration, and malaise.
However, when a severe case of the disease is encountered, more symptoms
may be involved like septicaemia with leucopenia, endocarditis, pericarditis

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or other types of illness, such severe cases are encountered in babies, young
children and sick or elderly people. The mortality is up to 13 %.
Reservoir
The primary reservoir of salmonella bacteria is the vertebrate intestine,
which means that almost all animals could excrete the organisms. Animals
and human beings might harbor salmonella bacteria without showing any
signs of the disease, thereby acting as carriers of the disease.
Transmission
Salmonellae reach food in many different ways; either directly at slaughter
from animal or human excreta, from where they are transferred to food
through hands, utensils, equipments, flies etc. Food poisoning is more likely
to occur if the total number of microorganisms present is high. A smaller
number may have no ill effect. If the temperature and other conditions are
suitable, there can be a great multiplication in numbers of organisms i.e. if
food is allowed to cool and gently re-heated, or kept for sometime in a warm
room.
Foods involved
Almost any food may be contaminated with salmonellae and under
conditions of mishandling such food may become involved in the
transmission of salmonella. The foods commonly involved are the various
animal derived foods, like meat and meat products, milk and milk products,
and egg and egg products especially from infected animals. Flies, rats, and
mice may transfer salmonellae from fecal material to food.
Contaminated water can also act as a carrier by contaminating other foods,
but is not directly the vehicle causing the disease since salmonella bacteria
are found in very low numbers in water.
Control
There are many ways that can be employed to reduce the incidence of the
disease especially by improving sanitation and to prevent mishandling of
foods. Salmonella in domestic animals and contamination of foods during
processing must be controlled and salmonella in raw products destroyed by
processing. The following control measures have been shown to considerably
reduce the salmonella carrier rate and the related incidence of food
poisoning cases.

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i).The use in the farm feedstuffs free of salmonellae.
ii). Hygienic standards of animal husbandry including proper control of slurry
disposal, water supply and food protection from insects and rodents.
iii). Proper design of the slaughter lines and the adoption of efficient hygienic
methods of slaughter and carcass dressing which minimizes contamination.
iv). Proper sewage treatment and disposal.
v). Bacteriological monitoring, which should include a presence /or absence
tests for salmonellae.
vi). Efficient refrigeration and hygienic handling of food.
vii). Avoidance of consumption of raw meat, unhygienic handling in the
home, and the use of storage systems which contribute to the proliferation
of bacteria of all types.
viii). Complete thawing of frozen meats and adequate cooking to ensure
destruction of potential pathogens and spoilage organisms.
ix). Heat processing of meat and poultry in a sanitary manner and such as to
avoid cross contamination.
x). Pasteurize egg and milk products and keep them cool.
Typhoid/Paratyphoid fever (Enteric fevers)
Enteric fevers include typhoid and paratyphoid fevers caused by Salmonella
typhi and Salmonella paratyphi A, B and C respectively. The typhoid and
paratyphoid fevers are clinically and pathologically similar regardless of
causal agent and only bacteriological examination can differentiate between
them. The serotypes are similar to other salmonella bacteria, but unlike
them, they are essentially parasites of man..
The disease symptoms
The incubation period is usually about 2 weeks, but might vary between 3
and 28 days for typhoid fever and between 1 and 15 days for the
paratyphoid fevers. The enteric fevers are generalized septicemia infections
with a frequent, if not constant bacteriaemia during the first two weeks of
the disease. The abdominal symptoms are severe, while fever and illness

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may continue for 4-6 weeks. Generally the paratyphoid fevers have a short
duration. The case fatality rate is approximately 10 %.
Reservoir and epidemiology
The typhoid and paratyphoid bacilli are essentially human parasites and are
acquired mostly from human sources, namely, patients and carriers. The
bacteria can be transmitted through contaminated water, milk or food. Only
a few organisms are needed to cause disease.
Control measures
1. Hygienic control of food and water supplies
2. Detection and treatment of chronic carriers and
3. Vaccination using TAB-vaccine. Protection by this vaccine is maintained
for 5-7 yrs.
Campylobacteriosis
Campylobacteriosis is a foodborne disease caused by Campylobacter jejuni
and Campylobacter coli which are associated with acute enterocolitis in man.
The disease can be acquired from a variety of animals including poultry,
pigs, wild animals and birds. The organisms are important causes of diarrhea
illness in all age groups of persons throughout the world, resulting in
diarrhea, abdominal pain, fever nausea, vomiting, and abdominal
complaints. Campylobacter jejuni occur in large numbers in cattle feces, and
poultry as normal flora. Infection in humans is characterised by
gastroenteritis and diarrhea.
Clinical signs
Incubation period ranges between 2-11 days with an average of 3-5 days. It
is preceded by fever, followed by diarrhea, which runs for 3-4 days then it
reduces. Abdominal pain is associated with backache, and a high mortality.
Death only occurs due to other complications. The condition is self-limiting
lasting up to 10 days. The jejunum and ileum are primarily affected with
extension to the colon resulting in acute inflammation and in occasions
abscess formation.
Mode of infection

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Infection occurs by ingestion of organisms in contaminated foodstuffs and
water. Incriminated food includes meat or water, or from contact with
infected animals, unpasteurized milk and possibly cross-contamination from
these sources to foods eaten uncooked or unrefrigerated. Carelessness in
the kitchens e.g. cutting chickens with the same knife used to cut other
foods without prior cleaning. Pork is a major source of C. coli, which is
mostly found as commensals in pig intestines, Contamination of pork occurs
during slaughter. Red meat e.g. lamb and beef are not major causes.
Preventive measures
1. Thorough cooking of all foodstuffs derived from animal sources especially
poultry.
2. Prevention of re-contamination after cooking.
3. Proper refrigeration of foods.
4. Recognition, control and prevention of campylobacter infections in
animals, and
5. Maintenance of high standard of hygiene.
Escherichia coli food borne infection
Escherichia coli are potential food poisoning pathogens which are widely
distributed in food environments in low numbers. E. coli strains involved in
food borne gastroenteritis fall into the following groups :(i).
Enteropathogenic E. coli (EPEC), (ii). Enterotoxigenic E. Coli (ETEC), (iii).
Enteroinvasive E. coli (EIEC) and (iv). Enterohemorrhagic E. coli (EHEC).
Each class is composed of various and often unique O:H serotypes and
posses virulence characteristics of that class. The serotypes are
characterized by using O-somatic and H-flagella antigens.
Enteropathogenic E. coli (EPEC)
Most EPEC strains adhere to the intestinal epithelial tissue and produce a
verocytotoxin. They produce moderate to severe watery, dehydrating
diarrhea, which may be associated with fever, respiratory symptoms and
abdominal distension. Duration of illness on average is about one week, but
some patients may have a longer course. EPEC is one of the few known
causes of chronic diarrhea in infants. Risk factors of death include: young

19. Page | 19
age and virulence of associated EPEC strain. Case fatality can be 70 % in
children less than 2 years.
Enterotoxigenic E. Coli (ETEC)
ETEC strains produce either heat stable enterotoxin (ST) or a heat labile
enterotoxin (LT), or both, as well as colonizing factor antigens represented
by pilli that mediate binding of cells to epithelial cells. These strains colonize
the human small intestines and cause an influx of secretions mediated by
the action of ST and/or LT enterotoxins.
Symptoms. The illness consists of watery non-bloody diarrhea, abdominal
cramps, and little or no fever. The symptoms usually lasts for 4 to 5 days,
and illness is mild in majority of patients, but a dehydrating cholera-like
picture may occur. The disease is however self-limiting, and is common in
children less than 5 years old. ETEC strains are the major etiological agents
of travelers' diarrhea. The illness is common among groups traveling from
low risk areas to high risk areas (e.g. developing countries). A relatively
large inoculum >108 cells/g is necessary to produce disease in adults.
Assurance of safe food and water is the best protection against diarrhea due
to ETEC strains.
Enteroinvasive E. coli
EIEC strains cause illness similar to shigellosis, as they have antigenic
relatedness to shigella. EIEC strains usually produce watery diarrhea in most
patients. In addition, there is fever, nausea, and abdominal cramps. Bloody
diarrhea may occur in fewer than 10 % of patients. The presence of mucus
and polymorphonuclear leucocytes in stool is typical of these strains. Illness
is usually self-limiting, lasting for 2 to 3 days. A relatively high dose (108
cells) is necessary to produce disease in volunteers. The median incubation
period is 18 hours (range 2-48 hrs). Food borne spread appears to be the
usual mode of transmission, although person-to-person spread has also
been reported.
Enterohemorrhagic E. coli
Escherichia coli serotype O157:H7 causes hemorrhagic colitis in humans.
The serotype does not ferment sorbital or may do it slowly, but produce a
verotoxin which is cytotoxic to vero culture cells. Infection involves all age
groups and has been linked to ingestion of contaminated hamburger and
beef in many outbreaks.

20. Page | 20
EHEC infection is characterized by diarrhea, abdominal pain which may be
severe and vomiting. Few patients develop fever. Illness lasts for 4 to 8
days, although it may extend to 13 days for severe cases. Patients with
complications have bloody diarrhea, acute ulcerative or ischemic colitis and
sub-mucosal edema with severe colonic inflammation. Deaths due to E. coli
O157:H7 infections have been reported only in elderly patients and in
patients who develop the hemolytic uremic syndrome (HUS). HUS can be
recognized by acute renal failure, microangiopathic hemolytic anemia and
thrombocytopenia. Infection also precedes thrombotic thrombocytopenic
purpura (TTP), an illness that shares many clinical features with HUS.
Control: Control measures involve proper cooking of hamburger and other
meats, avoidance of cross-contamination of foods in the kitchen and good
personal hygiene. The organism O157:H7 is heat sensitive, but resistant to
freezing. It grows poorly at 44C-45C, with no growth at 45.5C, suggesting
that its presence may not be detected by fecal coliform assay test.
Listeria monocytogenese infection
Listeria monocytogenese is a gram positive bacterium that is pathogenic to
both animals and human beings. The organism is widespread in nature and
is a transient constituent of the intestinal flora excreted by 1-10% of healthy
humans. It is extremely hardy and can survive for many years in the cold in
naturally infected sources. In animals, it causes abortion and mastitis, while
in man it can cause abortion in pregnant women as well as meningitis in
newborn infants and immunocompromised adults. Pregnant women, infants
and elderly people are at particular risk from listeriosis. The infection is fatal
in susceptible individuals with a mortality of 25-30%.
In the last few years, there has been an increasing number of Listeria
monocytogenese type 1-4 food borne infections caused by consumption of
vegetables, pasteurized milk and soft cheese and meat and products. One
such outbreak occurred in California where a large outbreak was reported in
1988 among pregnant women and or their children that caused by
consumption of Mexican-style cheese in which L. monocytogenese serotype
4B was identified. Deaths were reported in fetuses, neonates and other
individuals with compromised health status. A small portion (3-4%) of milk
used for preparation of cheese was not pasteurized in order to add the flavor
of raw milk to cheese. What flavor was to be added?
In 1981, a large outbreak caused by chilled cabbage occurred in East
Canada. Listeria monocytogenese serotype 4B was isolated from the

21. Page | 21
patients, as well as from cabbage kept in the refrigerator. A total of seven
cases were observed in adults and 34 perinatal cases. The death rate among
babies was 27 %, while 31 % adults suffered from meningitis. The cabbage
originated from the farmer who used cattle manure for the crops. Two cows
had recently died from listeriosis and the cabbage was grown on a field
where manure from the cows had been used as fertilizer. The cabbage was
kept in chilled conditions at the farm until it was sold to a salad producer
immediately before the outbreak.
Vehicle foods
In USA, Canada, Mexico, UK and Switzerland, large-scale outbreaks of
listeriosis have been associated with the consumption of various foods
(including milk, ice cream, cheese, poultry, sauerkraut, salads, sea foods,
meat and meat products contaminated by Listeria. The majority of the cases
of listeriosis in humans are associated with the consumption of Listeria-
contaminated foods. Delicatessens and other ready-to-eat foods may also be
important in causing food Listeria food poisoning. Raw milk or cheese made
of unpasteurized or insufficiently pasteurized milk play an important role in
the epidemiology of the disease.
Preventive measures
Among the measures recommended for reducing the incidence of listeriosis
in humans are serological testing of pregnant women and careful monitoring
of the quality of foods including conditions of processing and storage. It is
almost impossible to eliminated Listeria monocytogenese from the food
supply because of its ubiquitous nature. However, by using a hazard analysis
critical control point approach, health hazards associated with this organism
can be minimized (Harber, 1991).
VIRAL FOODBORNE INFECTIONS
Infectious hepatitis (Viral hepatitis A)
This is cause by hepatitis virus A. The incubation period is long, being an
average of 30 days (range 15-50 days). It is a systemic infection
characterized by gastrointestinal manifestations and liver injury, fever,
malaise anorexia, lassitude, nausea, abdominal discomfort, bile in urine and
jaundice. The duration of the disease could be from a few weeks to several
months.

22. Page | 22
Hepatitis A may be acquired from fecal contaminated food or water, or from
direct contact with infected individuals. Person-to-person transmission is
particularly common between children and between sexual partners. Feces,
urine, blood of infected human cases and persons incubating or convalescing
from the disease are infectios mateials
Foods mostly involved are shellfish, water, milk and orange juices.
Control
1. Foods should be cooked thoroughly, virus survives 50oC for 30 minutes.
2. Shellfish should not be collected or produced in polluted waters
3. Personal hygiene
4. Vaccination of contacts, and
5. Serovaccination with immunoglobulin.
Viral hepatitis E
This was formally called enterically transmitted non-A, non-B hepatitis). It is
a waterborne infection that occurs as epidemics and/or sporadic cases. The
virus has been isolated from hepatitis epidemics in many countries including
Kenya. This disease primarily affects young adults, and is clinically similar to
hepatitis A but does not lead to chronic disease. However, among women in
the second or third trimester of pregnancy who contract the disease, about
15-20 % die of hepatitis.
Control
Proper cooking of food to eliminates the virus
Poliomyelitis
Poliomyelitis is an acute viral illness where the majority of infections remain
inapparent. Manifested illnesses include paralytic and non-paralytic forms.
This disease occur commonly in older people when infected. Symptoms
mostly seen are those of lower extremities, meningitis and general illness.
Reservoirs and epidemiology
Feces and pharyngeal secretions contain the virus. The main route of
transmission is oral-oral and fecal-oral routes. Foods involved include water
and milk which get contamination with feces, and pharyngeal secretions of

23. Page | 23
infected persons. The virus can be cultured from stool, pharyngeal swabs
and spinal fluids of diseased patients. Serology e.g. CFT is frequently used
for diagnosis.
Control
Vaccination against the disease is the most important measure. Live and
killed vaccines are available. Personal and food hygiene must be practiced.
Prevalence in Kenya
Disease occurs in Africa especially where vaccination is taking place. The
threat can be reduced with large scale vaccination campaigns.
RICKETTSIAL FOODBORNE INFECTION
Q-Fever
Q-fever is caused by Coxiella burnetti and has an incubation period of
between 2-4 weeks. Symptoms include a sudden onset of fever, dry cough
and chest pain due to a pneumonitis. Hepatic disorders which include slight
jaundice occur in severe cases. Mortality is low with complete recovery.
Reservoir and epidemiology
O-fever is mostly an occupational disease among people who handle
livestock and raw animal products (e.g. farm and slaughterhouse workers
etc). Consumption of raw milk, contaminated butter and cheese, contact
with infected placentas, contaminated straw beddings and animal carcasses
or slaughterhouse offal are considered important.
Diagnosis
1. Serology including CFT micro-agglutination and FAT.
2. Isolation of agent (in well equipped laboratory due to the high risk of
infection).
Control
1. Pasteurization of milk (heating at 66C for 30 min or 75C for 15 sec).
2. Safe disposal of offal

24. Page | 24
FOOD BORNE INTOXICATIONS
Food borne intoxications are diseases caused by consumption of:
1. Toxicants which are found in tissues of certain plants and animals.
2. Metabolic products (toxins) formed and excreted by microorganisms
(such as bacteria, fungi and algae), while they multiply in food, or in
gastrointestinal tract of man.
3. Food containing poisonous substances, which may be intentionally or
unintentionally added to food as a result of producing, processing,
transporting or storing.
Food borne intoxications have short incubation periods (minutes to hours)
and are characterized by lack of fever. Food borne intoxications can be
classified into:
(1). Bacterial intoxications
(2). Fungal intoxications
(3). Chemical intoxication
(4). Plant toxicants and
(5). Poisonous animals.
BACTRIAL FOOD BORNE INTOXICATIONS
Staphylococcus aureus intoxication
This is a type of food borne intoxication caused by consumption of food
contaminated with staphylococcal enterotoxins produced by certain strains of
Staphylococcus aureus while growing in food. The organism produces
serologically different enterotoxins. Five staphylococcal enterotoxin A(SEA),
Staphylococcal enterotoxin B (SEB), Staphylococcal enterotoxin C (SEC),
Staphylococcal enterotoxin D (SED) and Staphylococcal enterotoxin E (SEE)
have been involved in food poisoning. The recently other staphylococcal
enterotoxins (SEG, SHE, SEI, SEK, SEL, SEM, SEN, and SEO) have been
identified. However, the relationship between these new enterotoxins and

25. Page | 25
human food poisoning is not fully understood. It is known that 95 % of
staphylococcal food poisoning outbreaks are caused by types SEA to SEE.
The remaining 5% of outbreaks may be associated with the new
enterotoxins. Individual strains of S. aureus may produce one or more
enterotoxin types in food or in culture. The percentage of the strains that are
enterotoxigenic differ widely depending on the source of the isolate.
Characteristics and growth conditions
Staphylococcus aureus is a facultative anaerobe, non-spore forming gram
positive cocci. It grows at a temperature between 12-44C (optimum 37C)
and pH range 4.0-9.83 (optimum 7.4-7.6). Growth occurs in an environment
containing up to 18 % sodium chloride and water activity of 0.86 - 0.88
when growing aerobically and 0.9 under anaerobic conditions. Toxin
production occurs at growth temperature 12-44C, pH  4.2 and salt
concentration of  10%. No toxin production occurs at temperatures below
12C, pH < 4.2 and > 10 % salt.
Nature of enterotoxins
All the staphylococcal enterotoxins are heat stable (withstanding heating at
100C for one hour) and ordinary cooking procedures, pasteurization and
drying do not inactivate these enterotoxins. They are insensitive to pH
changes(pH stable) and resistant to most proteolysis enzymes (trypsin,
chymotrypsin renin, papain and pepsin). The enterotoxins are also not
affected by irradiation. All the five enterotoxins have been reported to cause
food poisoning and have the same potency.
Competition with other organisms
Staphylococcus aureus is a poor competitor and therefore grows poorly or
not at all in a mixture of other microorganisms. Majority of S. aureus food
poisoning are due to foods in which the microbial flora is substantially
reduced, where they grow well and produce high yields of enterotoxins.
Foods with substantially reduced flora are such as cured meats (which
contain high salt concentrations that are inhibitory to other microbial flora
selecting for S. aureus), and cooked foods which are contaminated before
consumption.
Reservoirs
Staphylococci are found in varying numbers in air, dust water, food, feces
and sewage. The primary habitat of S. aureus is the mucous membranes of

26. Page | 26
the nasopharynx and skin of man, animals. The organism is found in the
nose, skin, saliva, intestinal contents and in feces. Human carriers of this
organism are numerous and are undoubtedly the source of a number of
outbreaks. Contamination of foods may be traced to food handlers with
minor septic hand infections or severe nasal infections, with subsequent
heavy growth of the organism on the food medium and production of
sufficient enterotoxin to evoke gastrointestinal symptoms in man. The nasal
mucous membrane is another particularly important source of staphylococci
of human origin.
Vehicle foods
Foods involved are those in which the microbial flora is substantially
reduced, such as boiled/cooked or processed milk and meat, cured meats
and meat products which are later contaminated. Milk products involved
include pasteurized milk, yoghurt, butter, chocolate milk, fermented milk.
Other foods include cream filled pastries, poultry, fish, shellfish, non meat
salads, egg and egg products, vegetables and cereal products. Studies have
found that increased handling of foods increases contamination with
enterotoxigenic S. aureus, suggesting that man is a major source. Mincing of
meat for example, increases contamination with enterotoxin producing S.
aureus strains.
Mode of transmission
1. Contamination from food handlers, containers etc
2. Cross contamination from raw foods
3. Improper heat treatment of raw foods
Disease symptoms in man
Symptoms of staphylococcal food poisoning occurs 1-6 hrs after
consumption of food contaminated with at least 1.0 microgram of
enterotoxin. Clinical signs include salvation, nausea, vomiting, abdominal
cramps, sometimes diarrhea with prostration. It has an attack rate of 5-
100%, but fatalities which occurs in children, the old and debilitated victims
are rare. Duration of illness is 24-72 hrs. Dose of 1.0 g or more is needed
to cause disease.
Preventive measures

27. Page | 27
1. Practice good personal hygiene including good personal conduct in food
establishment and when handling food.
2. Fast cooling of cooked food and keeping such foods at low temperatures.
Bacillus cereus food borne intoxication
This is a food borne intoxication caused by consumption of enterotoxins
produced by some strains of Bacillus cereus bacterium. The organism is
facultative anaerobic, spore-forming, Gram-positive and motile by
peritrichous flagella. Germination and growth of spores occur at
temperatures between 4-55oC (optimum 28-38C) and pH range 4.3-9.3.
The minimum water activity for growth is 0.95 and in less than 7 % sodium
chloride. Growth decreases with increasing salt concentration. High salt
concentrations and extreme pH values inhibit growth of the organism.
Spores are highly resistant to heat dehydration and other destructive
factors.
Reservoirs
Bacillus cereus is widely distributed in nature and are normally present in
soil, dust and water. Spores of this organism may contaminate food and
especially of plant origin such as cereals, potatoes, and spices. Spores may
also be found in milk, meat and meat products.
Cause of intoxication
Bacillus cereus food poisoning is caused by ingestion of any of the following
enterotoxins produced by these organisms while growing in food:
1. Diarrhea enterotoxins. The diarrhea enterotoxins are heat labile,
sensitive to enzymes trypsin, and pronase, and pH changes. They are most
stable at pH range of 5.0 to 10.0, but losses activity rapidly outside this
range. They are inactivated at pH below 4.0. Production is favored at pH
6.0-8.5, (optimum 7.0-7.5), and temperature of 18-43oC and low oxygen
and most is produced at the logarithmic phase. The toxin causes diarrhea
syndrome when consumed in food
2. Emetic toxin (cerulide). The toxin is produced in food by some strains
of B. cereus especially H-1 serovas. The toxin is a heat stable (withstand

28. Page | 28
126oC for 90 min) and resistant at pH range 2-11. It is resistant to trypsin
and pepsin and remains active at 4oC for 7 days. The toxin causes emetic
syndrome when comsumed in food. It is cytostatic, i.e. inhibits growth of
HEp-2 cells and is non-hemolytic. Enterotoxigenic strains can grow at 6oC
and 37oC are regarded as potential food poisoning organisms as they can
grow both in the food product and in the ileum. However, no enterotoxin
production occurs at 4oC.
Foods involved
Bacillus cereus is a common soil saprophyte and is easily spread to many
types of foods, especially of plant origin, but is also frequently isolated from
meat, eggs and dairy products. Cereal dishes e.g. rice, spice, mashed
potatoes, herbs, vegetables, minced meat, cream and milk pudding have
been involved in B. cereus poisoning.
Bacillus cereus does not compete well with other microorganisms but spores
can withstand heating at 100oC for 5 min. Spores of some strains can
withstand even higher temperatures (135C for 4 hours) and particularly if
food has a high fat content, which seem to have a protective effect. Spores
grow well after cooking and cooling to 48C during storage. The heat
treatment will cause spore germination, and in the absence of competing
flora, B. cereus grows well and produce enterotoxins. Some additives such
as garlic extract have an inhibitory effect on bacterial growth.
Mode of transmission to foods
1. Contamination due to improper handling.
2. Insufficient heat treatment to destroy spores.
Symptoms of disease in man
1. Emetic syndrome
The syndrome is characterized by nausea, vomiting, abdominal cramps and
sometimes diarrhea that occur 1-6 hrs after consumption of contaminated
food. The syndrome is associated with ingestion of rice and pasta based
foods.
2. Diarrhea syndrome

29. Page | 29
In the diarrhea syndrome, patients experience profuse watery diarrhea,
abdominal cramps and tenesmus, beginning 8 to 16 hours after ingestion of
contaminated food. Fever is absent and symptoms resolve within
approximately 12 hours. Vomiting is not a common symptom in this type of
syndrome.
Prevention
1. Good hygiene should be observed.
2. Low temperature and fast cooling of food.
CLOSTRIDIUM PERFRINGENS FOODBORNE INTOXICATION
This is a food borne intoxication caused by Clostridium perfringens
enterotoxin (CPE) produced in the gastrointestinal tract by enterotoxigenic
strains of C. perfringens. This organism is a spore-forming, anaerobic, gram
positive bacillus. The organism is found in the soil, dust, water, sewage
marine sediments, decaying materials, intestinal tracts of humans and other
animals. Food poisoning strains have a variety of origins including human
and animal faeces, abattoirs, sewage and flies. Spores produced by these
organisms can resist boiling for 4 or more hours. If the spores are present
as contaminants on raw meat they may resist boiling or steaming, and on
slow cooling the spores will germinate into rapidly multiplying bacterial cells
which produce large amounts of toxin.
Cause of intoxication
Clostridium food borne intoxication is caused by the ingestion of food
containing large numbers of vegetative cells of enterotoxigenic C.
perfringens type A and some type C and D strains. These cells multiply in
the intestine and sporulate releasing Clostridium perfringens enterotoxin
(CPE). Sometimes CPE may be pre-formed in food, and once the food is
consumed, symptoms may occur within 1-2 hours. The strains are heat
resistant and survive heating at 100oC for 1 hr).
Characteristics of CPE
Clostridium perfringens enterotoxin (CPE) is a protein of molecular weight
35,000 Daltons, synthesized during sporulation. CPE is heat labile (destroyed
at 60oC for 10 min) and its activity is enhanced by trypsin.

30. Page | 30
Vehicle foods
The food involved are those that are prepared one day and served the next
day. The heating of such foods is inadequate to destroy heat resistant
endospores, and upon cooling and warming the endospores germinate and
grow. Cooking kills the vegetative cells of Cl. perfringens but activates
surviving spores which will germinate and multiply. Foods poisoning occurs
when the level reaches 107-108 cells/g of food, because a certain amount of
cells are needed in order to pass the stomach barrier (low PH) and initiate
growth in the intestinal tract. Foods that have been involved include red
meats, chickens, fish, pork, fruits, vegetables, spices etc. Growth is
enhanced by a low oxidation- reduction potential (Eh) that is achieved after
removal of oxygen by cooking, long slow cooling periods and anaerobiosis
(provided easily in a liquid mass of meat or food). It is important to note
that salted meats/foods are not usually involved in this type of poisoning as
the organisms does not tolerate high salt concentration.
Mode of transmission to foods
1. Directly from slaughter animals
2. Contamination of slaughter meat from containers, handlers dust, water
etc.
Symptoms of disease in man
Symptoms appear 6-24 hours after ingestion of a large number of viable
vegetative cells  5x108/g of food, but not after ingestion of spores. The
symptoms include nausea, intestinal cramps, pronounced diarrhea and
fever. Vomiting is rare and the duration may be one to two days.
Diagnosis
1. Use of clinical signs. Clostridium perfringens is implicated as a cause of
food poisoning outbreak by the appearance of typical symptoms (abdominal
pain and profuse diarrhea), 12-24 hrs following consumption of food.
2. Confirmation of the outbreak requires (a). Enumeration of C. perfringens
in foods and stool using selective media, and the detection of high levels
(counts of  105 cfu/g) of C. perfringens in the food and faeces of patients.

31. Page | 31
This is followed by demonstration of a common C. perfringens serotype.
(b).detection of enterotoxin in food and patient stool using serological
methods e.g. ELISA, RPLA etc.
Prevention
1. Proper cooking of food and eating freshly prepared foods.
2. Thorough washing and sanitation of containers
3. Hygiene handling of cooked food
4. Fast cooling of cooked food and storage in refrigerator in small quantities.
5. Proper re-heating of cold cooked food before consumption
6. Storage of leftovers or unused foods in freezers
CLOSTRIDIUM BOTULINUM FOODBORNE INTOXICATION
Clostridium botulinum food borne intoxication (botulism) is a type of food
poisoning caused by consumption of enterotoxins produced by strains of
Clostridium botulinum. C. botulinum is an obligate, spore-forming anaerobe,
Gram positive bacilli with terminal to sub-terminal spores. The strains are
divided into proteolytic and non-proteolytic according to whether they
hydrolyze proteins or not. The intoxication is caused by botulinal toxins A, B,
E, F and G, produced by C. Botulinum type A, B, E, F and G, while the
organism grows in food. Spores of C. botulinum type A can survive
temperatures of 120oC.
Growth characteristics
Proteolytic strains grow at a temperature range between 10-50oC, while
non-proteolytic strains grow at 3.3-45oC (optimum 35-37oC). Toxin
production occurs at growth temperature range between 25-30oC. Both
strains grow at minimum pH of 4.5. Toxin production occurs in food at an
optimum temperature of 25-37oC, pH  4.5, and water activity (aw)  0.93.
No toxin production occurs at aw < 0.93 and pH < 4.5. Eating habits e.g.
consumption of home canned and fermented products increase the risk of
outbreaks.
Reservoirs
Clostridium botulinum is a saprophyte found in the soil, water, and
decomposing manure. The organism is a natural inhabitant of the surface

32. Page | 32
layers of the soil and thus may easily contaminate fruit vegetables or other
cultivated produce. Spores have been found in animal tissues and
occasionally in the intestines of pig, ox and horse, which feed on
contaminated feed. Where meat foods are infected, soil contamination is the
most likely cause.
Characteristics of botulinal toxins
Botulinal toxins are highly toxic, heat sensitive (inactivated by heating at
80oC for 10 min) neurotoxins,. They are unstable at alkaline pH (but stable
below pH 7.0). They are resistant to pepsin and acidic environment.
Botulinus toxin is one of the most powerful poisons known. The calculated
lethal dose for an adult man is in the region of 10 g. The toxins can resist
the action of the gastric and intestinal juices.
Types of foods implicated
Foods associated with anaerobic conditions and soil contamination such as
home-canned foodstuffs, or hams and bacon stacked without air access, are
particularly liable to be infected. Home made fermented foods have been
incriminated, together with smoked, pickled and canned foods that are
allowed to stand and then eaten without adequate cooking.
Botulism is associated in practically all outbreaks with consumption of
smoked, pickled or canned foods, not because these foods promote toxicity
of the organism, but because they are foods most likely to be eaten straight
out of the can, and without a further heating to destroy the any available
toxin. Uncooked fresh foods are safe because they are eaten before the toxin
has had time to develop, while, if foods are cooked, the toxin is destroyed.
In most, but not all cases of botulism, the preserved foods have been
noticeably spoiled, showing evidence of gas formation, breakdown and
rancidity.
For canned foods contaminated with C. botulinum, the can is often blown,
and the food is soft and disintegrated, with an odor resembling butter or
cheese, although meat foods so contaminated often show evidence of
spoilage. Preserved foods such as beets, olives, spinach or string beans may
contain potent C. botulinum toxin without the presence of obvious change in
the appearance, taste or odor. Infant botulism occurs due to consumption of
C. botulinum spores in honey and syrup. The spores germinate in intestines
where they produce the potent toxin.

33. Page | 33
Role of preservatives in food
Preservatives such as salts especially nitrates/nitrites reduce chances of
growth and inhibit toxin production. The danger of botulism has been the
deciding factor in the formulation of food processing techniques, especially in
meat canning.
Mode of transmission
1. Contamination due to improper handling.
2. Insufficient heating to destroy spores.
3. Spores present in animal tissues e.g. fish.
Symptoms of the disease in man
Symptoms of botulism are produced by the action of a powerful neurotoxin
which possesses an affinity for nerve tissue. The period of incubation in man
is usually under 24 hrs, but may be longer(range 12-72 hrs). Symptoms
include nausea, vomiting, fatigue, dizziness, headache, dryness of skin,
mouth and throat, constipation, lack of fever, nerve paralysis and great
muscular weakness, double vision, respiratory failure and death. Duration of
illness is 1-10 days and mortality is high up to 60-100% of affected persons.
The earlier the appearance of symptoms, the higher the mortality rate.
Diagnosis
1. Use of clinical symptoms
2. Isolation of C. botulinium strain from food.
3. Demonstration of botulinal toxins in suspected food, patient serum, vomit
and stool using the following methods:
i). Biological methods e.g. mouse challenge and protection test
ii). Serological methods e.g. diffusion, electrophoresis, ELISA etc.
Prevention
The following measures can help in the prevention of outbreaks:
1. Ensuring proper manufacturing practices.
2. Increasing salt concentration of food to 10% or more.

34. Page | 34
3. Preserved foods possessing rancid or other odors should be rejected.
4. Ensure proper hygiene of the cans, their transport, handling, storage
5. Proper heating of food before consumption to destroy heat labile
enterotoxins. Food should be heated to  80oC and temperature maintained
for at least 10 min before eating.
6. Ensuring fast cooling of food. This will ensure that spores that may be
remaining do not germinate in food grow and produce toxin.
FUNGAL FOOD BORNE INTOXICATIONS
Fungal intoxications are caused by consumption of metabolites produced
by fungi, when growing in food. These metabolites are called mycotoxins.
Grains, oilseeds, fruits and vegetables are mostly involved if they are stored
at high humidity (> 0.75) or if they are not properly dried before storage.
Poor dry storage practices of grains and other foods leads to mould growth
and production of mycotoxins. Of significance to public health is
aflatoxicosis.
Aflatoxicosis is caused by aflatoxins produced by the fungi Aspergillus
flavus. Four types of aflatoxins have been described i.e. aflatoxin B1, B2, G1
and G2. In addition, M1 and M2 metabolites of B1 may be secreted in milk.
Effects of aflatoxins
1.When consumed in large doses, they are lethal in causing acute
hemorrhagic syndromes
2. Sub-lethal doses cause histotoxic changes
3. Long term consumption of small doses cause liver tumors as these are
potent carcinogens, especially aflatoxin B1.
Prevention of aflatoxicosis
1. Proper drying and storage of grains and other affected foods
2. Quality control of potentially hazardous foods to ensure that they do not
contain above the allowable limits of 20 ppb before consumption by use of
appropriate analytical tests.

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3. use of fungicides as seed dressings to protect stored cereals and other
foods like pulses and potatoes.
CHEMICAL FOODBORNE INTOXICATION
This is a type of food borne intoxication arising from consumption of food
containing poisonous chemicals, which may be intentionally or
unintentionally added to foods as a result of producing, processing,
transporting or storage. A number of substances can enter the food chain
from the environment and through their use as growth promoters or
veterinary therapeutics giving rise to chemical residues. Radionuclide may
contaminate the environment, milk, meat and food crops as it happened in
the Chenobyl nuclear disaster of 1986 in U.S.S.R which contaminated large
areas of Russia and some parts of Europe. Chemical food borne intoxication
involve the following substances:
1. Heavy metals e.g. antimony, mercury, arsenic, flouride, lead, cadmium,
cyanide etc.
2. Pesticides and insecticides e.g. DDT, BHC Organochlorines and
organophosphates.
3. Herbicides
4. Fungicides e.g. organomercurials
5. Preservatives e.g nitrites, nicotinate, etc
6. Antibiotics e.g Pencillin, tetracyclines, chloramphenicol
7. Radionuclides e.g cesium, strontium, radium, molybdenum, barium,
ruthenium, lanthanum, iodine isotopes etc.
These compound usually enter foods through:-
(a) Accidental contamination by (i). Heavy metals, (ii) Pesticides, and (iii)
radionuclides.
(b) Intentional addition e.g preservatives such as nitrite and sodium
nicotinate for color preservation and fungicides used as dressing during
storage.

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(c) Leaching from containers e.g zinc galvanized containers by acid foods,
copper surfaces, lead pipes, asbestos roofs.
(d) Presence of such chemicals in food as a result of use of their use in
animal and crop husbandry
(e). Maliciously added to cause harm (is rare).
Clinical signs and symptoms
Food borne intoxication due to poisonous chemicals exhibit a very short
incubation period, usually a few minutes to a few hours, with an average of
one hour. Symptoms are mainly due to effect on gastrointestinal tract and
central nervous system and include nausea, headache, convulsions,
gastrointestinal irritation, abdominal cramps, vomiting and diarrhea, pallor,
cyanosis, blurred vision, sweating, flushing of skin and collapse. Other signs
may be due to effects on circulatory system.
Symptoms of radionuclide toxicity depend on dose, time and organ affected.
Toxicity causes (i) genetic effects including lethal mutations and reduction of
the lifespan. (ii) somatic effects such as radiation sickness, leukemia,
tumors, malformations and other physical ailments.
Measures to prevent spread by food
1. Discontinue use of utensils or containers that are able to leach chemicals
such as antimony, cadmium, zinc, copper, etc.
2. Use of coloured pesticides and proper storage of the same.
3. Wash leafy vegetables and prevent contamination by protecting food and
utensils when using insecticides.
4. Prevent acid foods or carbonated liquids from contact with exposed
copper.
5. Discontinue use of cyanide silver polishes or exercise care in their use.
6. Discontinue use in food establishments of pesticides containing fluorides.
7. Prevent misuse or avoid use of dangerous additives
8. Education of persons preparing food (e.g. possibility of Zn poisoning).

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9. Ensure that withdrawal periods are observed after use of these chemicals
in animal and crop husbandry.
.

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MEAT BORNE ZOONOSES
Zoonoses are diseases and infections that are naturally transmitted from animals to
humans or from human beings to animals.
Anthrax
This is an acute bacterial infection caused by Bacillus anthracis that occurs frequently in
herbivorous animals. However, all warm blooded animals are susceptible to varying
degrees. Grazing animals are infected when foraging in areas contaminated with spores
of B. anthracis. The disease is typified by sudden death in domestic and wild animals.
Terminally ill animals bleed from the nose, mouth, and bowel thus contaminating soil or
watering place with the bacteria. The disease has a worldwide distribution. Human
infection occurs as a result of contact with animals that have anthrax through:
1. Butchering and skinning
2. Consumption of contaminated meat
3. Contact with contaminated hides ans skins, goats hair, wool or bones.
The following three forms of the disease occur in humans.
i). Cutaneous form
This is characterized by lesions found on exposed areas of skin that results from
introduction of spores into the skin through cuts, abrasions, fly bites. In most (80-90%)
cases, the lesions heal spontaneously. In untreated cases 10 to 20% progress to a
systemic infection characterized by high fever and death
ii). Pulmonary form
It results from inhalation of B. anthracis spores which are deposited directly into lungs.
The spores then spread to regional lymph nodes and cause generalized infection is
followed by and rapid death.
iii). Gastrointestinal form
This form results from consumption of contaminated meat. The symptoms are variable
and include: fever, nausea, vomiting, abdominal pain, bloody diarrhea, sometimes
rapidly development of fluid in the belly, with massive diarrhea in some cases and death
if untreated.
In meat inspection an anthrax case may be seen as:
a) Dead animals on transport vehicle on arrival at slaughterhouse
b) Dead animals in the lairages

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In both cases, there is blood oozing from the natural openings. Great care should be
taken when suspect material is handled.
The diagnosis is established by:
a) Direct microscopy of blood smear or organ samples (always done when suspects
are found)
b) Cultivation – characteristic microscopic appearance
c) Inoculation of material intra-peritoneally into mice – will die within 3 days. Sub-
culturing is then done from dead mice.
d) Serology (Ascolis thermo-precipitation test)
When an anthrax case is diagnosed, the carcass and other materials should be burned
or deep buried with lime on top. If material is to be transported, care should be taken
not to contaminate during transport (head of the animal covered with plastic bag, etc).
The contaminated areas should be thoroughly disinfected, and people who have been
in touch with infected material should be given doses of penicillin and vaccinated.
Staining for presence of capsules
1) Blood smear fixed, either by good heat fixation or with 1% mercury chloride.
2) Staining with polychromethylene blue shall act on the bacteria for 3-5 minutes, then
washed off and dried.
3) Microscopy with oil immersion. Look for blue bacteria with purple capsule.
Control measures
1) In slaughterhouse – all operations must be halted until diagnosis is confirmed. If
positive, all exposed carcasses must be destroyed and premises carefully
disinfected with caustic soda within 8 hours.
2) Deep (6 feet) burial or incineration for anthrax unopened cadavers. The grass
and soil in the vicinity of the cadaver is buried and area covered with quicklime.
3) Affected herds should be quarantined for 2 weeks from last case with no animal
or product allowed out of the farm or slaughterhouse.
4) Environmental and personal hygiene where animals products are handled
5) Prompt treatment of persons in contact with infected carcasses
Tuberculosis
Tuberculosis is a communicable disease of worldwide occurrence that presents itself
with a respiratory problem in all animals including man. The disease is caused by

40. Page | 40
organisms of the genus Mycobacterium. The main species are: M. Tuberculosis (human
TB), M. bovis (Bovine TB) which is zoonotic .), M. microti, M. avium Two major types of
tuberculosis syndromes are recognized: (1). Pulmonary tuberculosis (PTB) and (2)
Extra-pulmonary TB. Epidemiology of human TB shows increasing incidence in both
developing and developed world. This is due to Increasing population density in poor
areas and HIV pandemic. TB in cattle leads to infection of various body organs including
the mammary glands which makes infected milking cows to shed mycobateria
organisms in milk urine, uterine secretions, faeces and sputum. The figure 3.1 below
shows multiple tubercles on the ribs and diaphgram of a bovine infected with
tuberculosis.
Figure 3.1: A. Multiple tubercles attached to the diaphgram of a bovine carcass; B.
Multiple tubercles attached onto the ribs of a bovine carcass.
A B

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Figure: Tuberculous pleuritis in cattle
Transmission of zoonotic tuberculosis. Humans can acquire the disease from animal
sources through:
1. Ingestion of raw and undercooked meat from infected animals
2. Inhalation of contaminated aerosols
3. Direct contact with materials contaminated with nose and mouth secretions of
infected animals
4. Postmortem examination of infected carcasses.
Human infection is characterized by chronic cough, weight loss, fatigue, profuse night
sweating, fever, general discomfort, intermittent fever, paleness, swelling of glands and
eventual death.
Diagnosis
Mycobacteria (M. tuberculosis, M. bovis, M. avium, leprae, M. paratuberculosis and
others) are acid fast. They are able to resist the aniline dyes that are commonly used
for staining of bacteria, because these bacteria contain large (74%) amounts of lipid
material that hinder the absorption of these dyes. In order to stain these bacteria, the
bacteria are exposed to the stain for long periods (hours) or heating could be used.
When they have accepted the stain, they are not easily destained, and even strong
mineral acids will not decolorize the bacteria giving the description “acid-fast bacilli”.

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PROCEDURE
1) Fix smear by heat
2) Flood the slide with carbolfuschin using a piece of filter paper to hinder
evaporation, heat over bunsen flame (not to hard). Repeat at intervals and
stain for 10 mins. Do not let the slide dry, add more stain if necessary.
3) Wash in running tap water
4) Pour 20% sulphuric acid on the preparation and leave for 15-30 seconds.
Repeat till the preparation has got a weak reddish colour = 10 min.
5) Wash in running water.
6) Counterstain with malachite green (Solution of malachite green, 0.5% in
water, or of methylene blue 0.5%) for 1 min.
7) Wash in water
8) Blot dry and examine in microscope using oil immersion.
Control
 Proper meat inspection to identify, isolate and condemn TB cases
 Proper cooking of meat before consumption.
Brucellosis
An infection caused by bacteria of the genus Brucella. Four species of Brucella cause
infection in man. These are: Br. Melitensis (affecting mainly sheep and goats), Br.
Abortus (affecting mainly cattle), and Animals acquire the disease by sexual
transmission or ingestion of contaminated feed..
The disease causes abortion in cattle, sheep and camel. Goats only develop lameness
and mastitis. Brucella organisms are continuously shed in milk of lactating animals,
uterine exudates, aborted fetuses and fetal membranes of aborting animals.
Disease in Human
The disease is occupational affecting human beings who work closely with animals such
as butchers, herders, meat inspectors, and veterinarians. Other people may be infected
through:
1. Consumption of raw or improperly pasteurized or raw milk from infected animals.

43. Page | 43
2. Consumption of dairy products such as cheese, and butter prepared from raw
milk from infected animals.
3. Contact with infected animals, aborted fetuses, or infected tissues and products
of abortion e.g. when assisting in difficulty calving.
4. Consumption of contaminated water and vegetables
Disease symptoms
The following three forms of the disease are recognized:
1) acute
2) localized and
3) chronic
Acute form. This is characterized by slow onset after an incubation period of between 7
and 21 days. Symptoms include headaches, fever alternating with chills (cold), severe
night sweats, joint pains, general muscular pain, aches, general body weakness, chest
pains and sometimes a non-productive cough. The signs of brucellosis can be confused
with those diseases that present with flu-like symptoms such as malaria, typhoid fever,
rheumatic fever, influenza and psittacosis. Most patients are anorexic and loose weight
Localized form. This may occur at any anatomic location. The most common signs
are: osteomyelitis, splenic abscess, gastroenteritis, pneumonia and endocarditis.
Endocarditis is the most common cause of mortality in brucellosis patients
Chronic form. The illness persists for more than 1 year following onset of brucellosis
symptoms with varied and mixed manifestations including joint pains, undulating fever
and night sweats among other symptoms..
Control in animals
1. Slaughtering of serologically positive animals and vaccination of young ones
2. Indiscriminate vaccination of all the animals in a region or country
3. Implemention of effective quarantine to restrict animal movement during
outbreaks.
4. Hygienic disposal of aborted fetuses, placentae and uterine materials thereafter
disinfection of contaminated areas.
5. All animals introduced in a farm should be isolated and tested before joining the
rest of the herd.

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Prevention of human infection
1. Employees of the meat industry should wear protective clothing, treat and dress
all wounds on hands and arms.
2. Ensure proper dressing and disinifection of wounds especially those on the
hands that may come into contact with brucella organisms.
3. Proper cooking of meat before consumption.
Rift valley fever
RVF is a viral disease transmitted by mosquitoes. Mosquitoes are numerous during
heavy rains and they transmit the infection among animals by biting. The disease has
been confirmed in at least 24 African countries.
Transmission: Principal mode of transmission among animals is by mosquito bites.
Human beings gets infected when they come into contact with infected animals
during: slaughter, necropsy, food preparation and laboratory activities.
Disease in animals
- Disease has a short incubation period of 20-72hrs.
- There is 95% mortality in newborns
- Abortion In pregnant ewes is common in sheep,
- In cattle there is abortion, fever, anorexia, profuse salivation, abdominal pains
and diarrhea. However, mortality in cattle is low.
Control
- In animals vaccination is the method of choice using inactivated vaccines
- Vaccination of pregnant females can cause abortion
- Should not be used in newborns or areas free of infection -could turn virulent
- Precautions in handling of sick/dead animals - use of protective clothing.
- Precautions in laboratories where work on virus is carried out.
- Care when conducting postmortem especially during outbreaks
Echinococcosis/hydatidosis
Echinococcosis/hydatidosis is a parasitic disease caused by Echnococcus granulosus.
The disease occurs worldwide.

45. Page | 45
Life cycle: E. granulosus adult worm is found in the domestic dog and a wide range of
wild carnivores who are the definitive hosts. The definitive hosts will pass out in their
faeces eggs which are highly resistant to environmental conditions and which remain
infective for a long time in favourable climates. However, desiccation and high
temperatures affect the longevity of the eggs. The intermediate hosts which include
domestic herbivores and a wide range of herbivores acquire infection by ingesting
infective eggs. In the stomach and small intestines enzymes act on the eggs to release
oncospheres from embryophored eggs.
Disease in Human: The clinical signs depend on the site and size of the cyst.
Abdominal swelling due to presence of cysts in the lungs, liver or any abdominal organ,
swelling of one or both eyes when the cysts affects the eyes.
Diagnosis: Done through meat inspection. Hydatid cysts are found in various internal
organs including lungs, liver and peritoneal cavity.
Hydatid cyst in the lung

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Hydatid cyst in liver
Figure: Hhydatid cyst in the lung and liver of cattle. Such cysts are also found in the
lungs and livers of camel, sheep and goats.
Preventive measures
 Creation of public awareness through health education,
 Control of livestock slaughter by centralization of slaughtering,
 Efficient meat inspection and proper disposal of offal
 Dog treatment and control and
 Periodic diagnostic testing of dogs.
 Dog owners to control movement of their dogs.
 Regular deworming of dogs with suitable anthelmintics e.g praziquantel
 Reduction of dog numbers by elimination of stray and surplus dogs
Tapeworm infection (taeniasis)
Taeniasis is a parasitic disease caused by Taenia Saginata. Adult tapeworm is found in
human intestines from where eggs are shed to contaminate the environment such as
pastures. Cattle come into contact with tapeworm eggs while grazing in these pastures
and consume them with the pasture. The eggs develop into larvae, which then lodge in
their muscles where they occur as cysts. When man ingests cattle meat having cysts,
larvae are liberated from the cyst which then develop into adult worms.

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The lifecycle of Taenia. saginata

48. Page | 48
Prevention and control measures
1. Proper meat inspection to identify infected meat
2. Proper disposal of sewage and other wastes to contamination of pastures
3. Construction and use of toilets/latrines
4. Regular de-worming of humans and cattle
5. Adequate cooking/roasting of meat to destroy cysts in the meat
Test for viability of cysticerci in meat
Low temperature treatment is in many countries enforced by law to render moderately
parasite infested meat safe for consumption. Best known is the low temperature
treatment (freezing at –10°C for 10 days) to kill Cysticercus bovis. To make sure that
the required treatment is performed in a satisfactory manner, the viability of parasites
present should be controlled.

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Cysticercus bovis ( C. bovis) in beef muscle
a) Carefully remove cysts from meat to petri dish
b) Add a saline solution of 30% ox bile, or a saline solution of 5% sodium taurocholate
c) Incubate at 37°C for 1-2 hours, cysts are considered dead of the scolex. If no
evagination within 2 hours cysts are considered dead.
Ruptured and fluid filled cysticerci

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Cysticerci in tongue muscle

51. Page | 51
HAZARD ANALYSIS AND CRITICAL CONTROL POINT (HACCP) SYSTEM
The HACCP system is a systematic approach that identifies and evaluates food safety
hazards and put in place measures and/or procedures that will either prevent, eliminate,
control or reduce the food safety hazard to acceptable levels. HACCP is the foremost
means of assuring food safety throughout the food chain, from primary production to
final consumption, particularly when used in combination with the pre-requisite
programs for GHP.
For efficient and effective application of the HACCP system, the establishment operator
must apply the seven HACCP principles namely: (1) Conduct a hazard analysis; (2)
Identify critical control points (CCPs); (3) Establish critical limits for each CCP; (4)
Establish CCP monitoring requirements; (5) Establish corrective actions; (6) Establish
procedures for ensuring the HACCP system is working as intended, and (7) Establish
record keeping procedures.
Principles of HACCP
There are seven principles of HACCP on which a food safety management system is
based. A food safety management system based on the principles of HACCP will
enable hazards to be identified and controlled before they threaten the safety of food
and your customers.
Identify the hazards and determine risks: Involves identification of hazard and
determination of the severity of the hazard associated risks. Hazard usually means the
contamination, growth or survival of microorganisms related to food safety or spoilage, a
dangerous chemical contaminant or foreign objects (glass or metal fragments). Risk is
an estimate of hoe likely it is that the hazard will occur. The risks are associated with
growing, harvesting, processing, distribution, preparing and /or using a raw material or
food product. Look at each step (e.g. purchasing, delivery, storage, preparation,
cooking, chilling etc.) in your operation and identify what can go wrong e.g. Salmonella
in a chicken product (biological hazard), detergent in a chicken product (chemical
hazard) or a piece of glass in a salad (physical hazard).
Determine the critical control points (CCPs) required to control hazard: A critical
control point is a location, practice, procedure or process which can be used to minimize
or prevent unacceptable contamination, survival or growth of food borne pathogens or
spoilage organisms or introduction of unwanted chemicals or foreign objects. Identify
the points in an operation that ensures control of the hazards e.g. Cooking burgers to a
minimum of 70°C for 2 minutes will kill E. coli O157 and other pathogens.

52. Page | 52
Establish critical limit(s): Determine and set critical limits to enable you to identify
when a CCP is out of control e.g. the temperature at the centre of a beef product
following cooking must reach a minimum 70°C for 2 minutes.
Establish a system to monitor control of the CCP: When CCPs and critical limits
have been identified it is important to have a way to monitor and record what is
happening at each CCP. Monitoring procedure enable one to determine that each CCP
is under control. Monitoring systems must be able to effectively determine if a CCP is
under control. Typically monitoring will involve measuring parameters such as
temperature and time. However, how you monitor and how often will depend on the size
and nature of your business. Monitoring should in all cases be simple, clear and easy to
use e.g. recording the final cooking temperature and time for a cooked chicken product.
Establish the corrective action to be taken when monitoring indicates that a
particular CCP is not under control: When monitoring indicates that a CCP is not
under control, corrective action must be taken e.g. the temperature of the food in a
refrigerator rises to 10°C due to a technical fault. Discard the food and repair the
refrigerator using the manufacturer’s instructions to ensure the correct temperature of
5°C is achieved.
Establish procedures for verification to confirm the HACCP system is working
effectively: Review and correct the system periodically and whenever you make
changes to your operation e.g. microbiological analysis of a chicken product to verify
that it is free of Salmonella bacteria before and after cooking. Verification is a procedure
that provides the guarantee to any customer and to the public that the product in
question is of the quality the producer is claiming, since it has bee based on specific
GAP, GMP and HACCP principles that are documented. If verification is performed by
independent agencies, bodies or companies that are accredited by nationally or
internationally approved quality assurance organizations, the procedure becomes a
certification procedure.
Establish documentation of all procedures and records appropriate to these
principles and their application: For the successful implementation of HACCP,
appropriate documentation and records must be kept and be readily available. It is
unrealistic to operate HACCP or to demonstrate compliance with the current legislation
without providing evidence such as written records. As with HACCP itself, the
complexity of the record keeping will very much depend on the nature and complexity of
the business. The aim should be to ensure control is maintained without generating
excessive paperwork e.g. cooking temperatures, delivery or cleaning records.

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Prerequisites for HACCP (Safety Support Measures)
Before implementing HACCP, food businesses must already be operating to standards
of good hygienic practice by having in place appropriate prerequisites These
prerequisites include where appropriate:
1. Appropriate design, layout and construction of slaughter and processing facilities
2. Appropriate equipment and layout
3. Establishment of routine cleaning and sanitation procedures
4. Personnel hygiene and training
5. Established pest control strategies
6. Support services (compressed air, ice, steam, ventilation, water etc)
7. Appropriate meat storage and transport facilities
8. Established waste management systems
9. Zoning (physical separation of activities to prevent potential food contamination)
The Benefits of HACCP to Food Businesses
HACCP provides businesses with a cost effective system for control of food safety from
ingredients through production, storage and distribution to sale and service of the final
consumer. The preventive approach of HACCP not only improves food safety
management but also complements other quality management systems. The main
benefits of HACCP are:
1. Saves business money in the long run
2. Avoids poisoning of meat customers
3. Meat safety standards are increased.

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FOOD SPOILAGE AND PRESERVATION
Food spoilage can be defined as food that has been damaged or injured, hence no longer
good for human use. Food must be considered spoiled if it is contaminated with pathogenic
microorganisms or various poisonous agents, like pesticides, heavy metals etc. In most cases
there does not need to be an evident sign of spoilage, the food might look normal and only after
eating if ,or by careful bacteriological and toxicological investigation, one is able to realize the
defect. Food decay or decomposition is implied when the term spoiled is used. The following are
the causes of food spoilage:
(a). Growth and activity of microorganisms. Bacteria, yeasts and molds are the microorganisms
that cause food spoilage. They produce various enzymes that decompose the various
constituents of food.
(b). Enzyme activity. Action of enzymes found inherently in plant or animal tissues start the
decomposition of various food components after death of plant or animal. These enzymes if
present in the food must be inactivated in order to preserve the food.
(c). Chemical reactions. These are reactions that are not catalysed by enzymes. Such reactions
include oxidation of fat, maillard reaction in milk between proteins and lactose which result in
unpleasant flavour and brown discoloration of food,a nd reactions between the food product and
packaging materials.
(d). Vermin. Vermin includes weevils,cocroaches, ants, rats, mice, birds, larval stages of some
insects. Vermin are important due to: (i). Aesthetic aspect of their presence, (ii) Possible
transmision of pathogenic agents, (iii). Consumption of food.
(e). Physical changes. These include those changes caused by freezing, burning, drying,
pressure etc.
Microbial spoilage of food
Bacteria, yeasts and molds are the major causes of food spoilage. They produce various
enzymes that decompose the various constituents of food. Molds are the major causes of
spoilage of foods with reduced water activity such as dry cereals and cereal product, while
bacteria spoil foods with relatively high water activity such as milk and products.
Factors that affect growth of microorganisms
pH. Most microorganisms grow best at pH near to neutrality (6.0-7.5). Few
microorganisms grow below pH 4.5. Bacteria grow in a narrow pH range between 4.4
and 9.0, while moulds and yeast grow in a wide pH range between 1.5 and 11.0.

55. Page | 55
Moisture content. The effect of moisture is in terms of water activity, which is the
vapor pressure of food substance to that of water at the same temperature. Most foods
have water activity of 0.99. Microorganisms require different water activity values. Most
spoilage bacteria need 0.91, yeast - 0.88, moulds - 0.80, halophiles - 0.75, xerophiles-
0.65 and osmophiles - 0.65 as the minimum water activity.
Type and level of nutrients in the food: Microorganisms require water, energy,
nitrogen, vitamins and minerals for growth. Different food have specific types of
nutrients required by microorganisms hence are susceptible to spoilage. Microorganism
grow well in high protein foods such as meat and milk.
Temperature: Microorganisms grow in a wide range of temperatures but most grow at
between 20-40oC. Microorganisms can be classified according to their temperature
requirements into: (i) Psychrophiles - grow between 20-30oC, (ii) mesophiles -grow
between 30-45oC, and (iii) thermophiles - grow at 55-65oC. Meat should be kept below
4oC to arrest rapid spoilage. Frozen meat have extended shelf-life of up to one year
Relative humidity: Relative humidity is related to water activity. Foods with low water
activity placed in high humid environment take up water and get spoiled easily. Meat
has high relative humidity, hence can easily be spoiled. Drying meat will reduce relative
humidity and this will arrest the rate of spoilage.
Oxidation-reduction potential: Various microorganisms require either increased
oxygen tension (are aerobic) or low oxygen tension (are anaerobic) for growth. Meat
kept under aerobic conditions are spoiled by aerobic and facultative anaerobes, while
canned meat is spoiled by anaerobic microorganisms including Clostridium botulinum
and Clostridim perfringens.
Meat preservation
Meat preservation is where chemical or physical agents prevent biological deterioration
of meat. The various characteristics that affect growth of microorganisms in meat can
be used to prevent growth of these microorganisms in food by inhibiting growth or killing
(destruction) of the organisms.
Inhibition of microorganisms can be through reduction of water activity (by salting and/or
drying), reduction of pH (achieved by fermentation or addition of organic acids), use of
preservatives, low temperatures storage (chilling or freezing) and smoking. Preservation
by smoking occurs through impregnation of chemicals such as phenols on the surface
of microbes in food, and drying effect due to associated heat.
Destruction of microorganism in food can be through heat treatment, irradiation and
uses of ethylene oxide or propylene oxide gases. Two methods of heat treatment are
commonly used in food preservation, i.e. pasteurization and sterilization.

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Pasteurization: is the process of heat treatment of a food substance at specific
temperatures and times aimed at destroying all pathogenic microorganisms without
affecting the nutritive qualities of such food. Three methods are used in pasteurization:
(a). Low temperature long time (63oC for 30 min),
(b). High temperature short time (72oC for 15 seconds),
(c).Flash method (80oC for 1-2 seconds).
Sterilization. is the use of physical or chemical means to destroy all the
microorganisms that are present in the food. Sterilization can be achieved by (i) heating
at high temperature and pressure, e.g. 100oC-140oC, (ii) irradiation, iii) filtration, using
0.22-0.45µm pore size filter membranes (iv) ethylene oxide or propylene oxide gases.
Irradiation. is a means of food preservation that use ionizing or electromagnetic
radiations to kill microorganisms in the food. The types of radiation which are useful for
this purpose are the gamma rays produced by radioisotopes cesium-137 and cobalt-60
and electron beams generated by electron accelerators. These radioactive radiation kill
bacteria either directly by hitting the bacterial cells or indirectly by creating reactive
compounds in the medium and in the bacterial cell. Application of ionizing irradiation to
foods is to obtain sterilization, extend the shelf-life, and eliminate pathogenic
microorganisms. High amount of irradiation in the food is however dangerous to human
health.
Preservatives. are widely used in the preservation of various food products including
soft drinks, fruit juices and other food products. These preservatives inhibit the
proliferation of microorganisms that might be present in food product, thus preventing
spoilage.
Food processing
Food processing is treating food in such a way as to make it safe for consumption,
increase their shelf-life (preservation) and make various value added products.
The most common method used in food processing is heat treatment, commonly
referred to as cooking by housewives and catering personnel. At industrial level, it is
referred to either pasteurization or sterilization. However In practice, a combination of
various preservation methods are used in the food processing.
Food storage conditions