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Ph viruses eac for finals
1. VIRUSES OF
PUBLIC HEALTH
IMPORTANCE
March 2012
PUBLIC HEALTH
“protecting and improving health through education and promotion of
healthy lifestyles and research for disease and injury prevention”
Saturday, March 3, 2012
4. FACTORS THAT LED
TO EMERGENCE
• Introduction of the agent into a new host
population, originating from:
• environment
• another host species
• variant of an existing human infection
• Establishment and further dissemination
within the new host population
Saturday, March 3, 2012
5. FACTORS THAT LED
TO EMERGENCE
• Microbial adaptation
• Mutation
• Natural selection
• antibiotic-resistant bacteria
• Evolutionary progression
• Virulence factors
Saturday, March 3, 2012
6. FACTORS THAT LED
TO EMERGENCE
• Human Susceptibility
• immune status
• nutrition
• age
• occupation, etc.
• Human behavior and demographics
• Affect disease dissemination
Saturday, March 3, 2012
7. FACTORS THAT LED
TO EMERGENCE
• Changing ecosystems / land use
• Argentine, Bolivian hemorrhagic fever
• changes in agriculture (grassland to maize) favoring rodent host
• Hantaviruses
• Ecological or environmental changes increasing contact with
rodent hosts
• Rift Valley fever
• agriculture, irrigation
Saturday, March 3, 2012
8. FACTORS THAT LED
TO EMERGENCE
• Economic development
• Dengue/DHF
• urbanization favoring mosquito vector
• Lassa fever
• urbanization favoring rodent hosts, increasing exposure
• Rift Valley fever
• dam building
Saturday, March 3, 2012
9. FACTORS THAT LED
TO EMERGENCE
• Technology and industry
• Hepatitis B and C
• transfusions, organ transplants
• Influenza (pandemic)
• possibly pig-duck agriculture facilitating
reassortment
Saturday, March 3, 2012
10. FACTORS THAT LED
TO EMERGENCE
• International travel and commerce
• Dengue/DHF
• Ebola, Marburg
• In Europe and US, importation of monkeys
• HIV
• Influenza (pandemic)
• SARS
Saturday, March 3, 2012
12. THE BASICS...
• Influenza is an acute, viral respiratory infection
• When to suspect?
• Fever, chills, headache, aches and pains throughout
the body, sore throat which may lead to
bronchitis or pneumonia
• Vomiting and diarrhea may also occur
• Many deaths have been attributed to influenza
Saturday, March 3, 2012
14. PANDEMICS
• PANDEMIC: world wide spread of infection
occurring in many countries simultaneously
• INFLUENZA PANDEMICS: occur approximately
every thirty years
• REASON FOR OCCURRENCE: new strain of
the virus emerges for which people have no
immunity and there are no vaccines available
Saturday, March 3, 2012
17. THE ABILITY OF INFLUENZA
TO CAUSE PANDEMICS
HA - hemagglutinin
NA - neuraminidase
helical nucleocapsid (RNA plus
NP protein)
lipid bilayer membrane
polymerase complex
M1 protein
Saturday, March 3, 2012
18. THE ABILITY OF INFLUENZA TO
CAUSE PANDEMICS
• Haemagglutinin (H)
• attaches the virus to
cells and allows the
viral envelope to fuse
with the cell membrane
and enter cells
• Neuraminidase (N)
• allow the release of
viruses to infect other
cells
Saturday, March 3, 2012
21. LIFE CYCLE & TRANSMISSION
• The virus is spread by
inhalation or by direct
contact
• Reservoirs of infection:
primarily humans, but birds
and pigs can act as reservoirs
• Multiple host status = mixing
of flu types
Saturday, March 3, 2012
22. CONTROL &
PREVENTION
• EDUCATION
• ISOLATION
• VACCINATION
• PROPER
HYGIENE
Saturday, March 3, 2012
23. VACCINE (H) & CHEMOTHERAPY (N)
Saturday, March 3, 2012
24. VACCINE (H) &
CHEMOTHERAPY (N)
Saturday, March 3, 2012
30. PATHOGENESIS
1.The virus is inoculated into
humans with the mosquito saliva.
2.The virus localizes and replicates
in various target organs, for
example, local lymph nodes and the
liver.
3.The virus is then released from
these tissues and spreads through
the blood to infect white blood
cells and other lymphatic tissues.
4.The virus is then released from
these tissues and circulates in the
blood.
Saturday, March 3, 2012
31. PATHOGENESIS
5.The mosquito ingests blood
containing the virus.
6.The vir us replicates in the
mosquito midgut, the ovaries,
nerve tissue and fat body. It then
escapes into the body cavity, and
later infects the salivary glands.
7.The vir us replicates in the
salivar y glands and when the
mosquito bites another human,
the cycle continues.
Saturday, March 3, 2012
32. WHY
DENGUE
HAS
EMERGED
Saturday, March 3, 2012
49. THE OUTBREAK
• In November 2002, highly contagious and severe
atypical pneumonia were observed in the
Guangdong Province of southern China
• The virus was spread to Hong Kong in February
2003 by a doctor who died 10 days after
admission into local hospital = a mysterious
death
• Similar outbreaks occurred at different local
communities subsequently
Saturday, March 3, 2012
51. SEVERE ACUTE
RESPIRATORY SYNDROME
(SARS)
• Cause : SARS CoV
• Highly infectious
• Mainly affects adults
• Superspreading events important in transmission
process
• No reports of transmission occurring before onset
of symptoms
Saturday, March 3, 2012
55. TRANSMISSION
• Evidence of person to person
transmission
• Close contact with body fluids
(especially respiratory droplets )
• Contaminated hands, clothes,
equipment; environment may also be
important
Saturday, March 3, 2012
