Descriptive.

2. What is an Arbovirus?
acronym for arthropod-borne virus
Arboviruses are a large group of viruses that
are spread by certain invertebrate animals
(arthropods), most commonly blood-
sucking insects
EPIDEMIOLOGY
found throughout the world
depends on the availability of specific types
of mosquitoes that can carry it and specific
birds or animals that can be infected

3. PREVENTION
 If possible, stay inside between
dusk and dark. This is when
most types of mosquitoes are
most active in their search for
food.
 When outside in mosquito-
infested areas, wear long
pants and long-sleeved shirts.
 Spray exposed skin with an
insect repellents, e.g.
Permethrin, DEET
 Screen homes to prevent
mosquitoes from entering.
 Remove old tires and other
water-holding containers from
around homes. These can
provide breeding sites for
mosquitoes.

4.  Alphaviruses  Bunyaviruses
 Eastern Equine  LaCrosse encephalitis
encephalitis  Reoviruses
 Western Equine  Colorado tick fever
encephalitis
 Venezuelan equine
 Orbivirus
encephalitis
 Colorado Tick Fever
 Flaviviruses
 African Horse Sickness
 St. Louis encephalitis
 Blue Tongue Viruses
 Japanese encephalitis
 Yellow fever
 Dengue

6. ERADICATED IN 1980.. one of the success stories
of medicine
PATHOGENESIS
Virus invades through broken skin,
replicates at the site of inoculation and
causes dermal hyperplasia and
leucocyte infiltration.
This causes lymphadenopathy and elicits
an immune response
The lesion of molluscum is circumscribed by
a connective tissue capsule and the
dermis

7.  Human monkeypox is usually acquired
via the respiratory tract
 During the 12th day of incubation period
viraemia distributes infection to internal
organs which get damaged by viral
infection
 Spread to skin initiates the clinical phase
and the lesions progress to classic stages
of macule to papule to vesicle to pustule
to crust
 Lymphadenopathy usually involving the
cervical and inguinal areas is often
marked

8. TREATMENT
Smallpox vaccination within three days of
exposure will prevent or significantly lessen
the severity of smallpox symptoms in the
vast majority of people
Other than vaccination, treatment of
smallpox is primarily supportive, such as
wound care and infection control, fluid
therapy, and possible ventilator assistance
No drugs available currently
Anti-virals like cidofovir, intravenously
administered might be useful

9. The family Poxviridae is
classified into 2 sub-
families :
Chordopoxvirinae and
Entomopoxvirinae
Chordopoxvirinae, the
poxviruses of
vertebrates, are
classified into 6
genera:
 Orthopoxvirus
 Parapoxvirus
 Capripoxvirus
 Leporipoxvirus
 Avipoxvirus
 Suipoxvirus

10. EPIDEMIOLOGY
Upper respiratory tract infections are the
most common infectious diseases
among adults, who have two to four
respiratory infections annually
Children may have six to ten colds a year
(and up to 12 colds a year for school
children).
.CAUSATIVE ORGANISM
Rhinoviruses, of the Picorna group

11. PATHOPHYSIOLOGY
The major entry point -the nose, but can also be the eyes (via
the nasolacrimal duct).
From there, it is transported to the back of the nose and
the adenoid area. The virus then attaches to a
receptor, ICAM-1, which is located on the surface
of cells of the lining of the nasopharynx.
The receptor fits into a docking port on the surface of the
virus. Large amounts of virus receptor are present on cells
of the adenoid.
After attachment to the receptor, virus is taken into the cell,
where it starts an infection, and increases ICAM-1
production, which in turn helps the immune response
against the virus.
Rhinovirus colds do not generally cause damage to the
nasal epithelium.
Macrophages trigger the production of cytokines, which in
combination with mediators cause the symptoms.
Cytokines cause the systemic effects. The
mediator bradykinin plays a major role in causing the local
symptoms such as sore throat and nasal irritation

12. PREVENTION
 Hand washing with plain soap and water is
recommended. The mechanical action of hand rubbing
with plain soap, rinsing, and drying physically removes the
virus particles off the hands.
 Alcohol-based hand sanitizers provide very little protection
against upper respiratory infections, especially among
children.
 Because the common cold is caused by a virus instead of
a bacterium, anti-bacterial soaps are no better than
regular soap for removing the virus from skin or other
surfaces.
 Aqueous iodine has been found to reliably eliminate the
cold virus on human skin, however iodine is not
acceptable for general use as a virucidal hand treatment
because it discolors and dries the skin.
TREATMENT
Help alleviate symptoms: simple analgesics
and antipyretics such
as ibuprofen and acetaminophen / paracetamol

13. CAUSATIVE ORGANISM: Haemophilus
influenzae
EPIDEMIOLOGY
Influenza reaches peak prevalence in winter
 Because the Northern and Southern
Hemispheres have winter at different times
of the year, there are actually two different
flu seasons each year
 An alternative hypothesis to explain
seasonality in influenza infections is an
effect of vitamin D levels on immunity to the
virus - Robert Edgar Hope-Simpson in 1965

14. PATHOPHYSIOLOGY
 The viral hemagglutinin protein is responsible
for determining both which species a strain
can infect and where in the human respiratory
tract a strain of influenza will bind
 Strains that are easily transmitted between
people have hemagglutinin proteins that bind
to receptors in the upper part of the respiratory
tract, such as in the nose, throat and mouth.
 In contrast, the highly lethal H5N1 strain binds
to receptors that are mostly found deep in the
lungs.This difference in the site of infection may
be part of the reason why the H5N1 strain
causes severe viral pneumonia in the lungs, but
is not easily transmitted by people coughing
and sneezing.

15. PREVENTION
 Inactivated influenza virus vaccines are
used for old people
 Vaccine contains the strains of type A and
B and early October to mid-November is
the best time to get vaccinated
TREATMENT
 Drugs like amantadine and rimantadine
hydrochloride are used against type A but not
against type B viruses
 These drugs interfere with virus uncoating and
transport by blocking transmembrane M2 ion
channel

16. EPIDEMIOLOGY
 According to the WHO,
measles is a leading cause of
vaccine-preventable
childhood mortality.
 Worldwide, the fatality rate has
been significantly reduced by
a vaccination campaign led
by : the American Red Cross,
the United States Centers for
Disease Control and Prevention
(CDC), the United Nations
Foundation, UNICEF and the
WHO.
 Globally, measles fell 60% from
an estimated 873,000 deaths in
1999 to 345,000 in 2005

17. PATHOPHYSIOLOGY
 The respiratory route and conjunctiva
acquire rubeola (measles) virus
 After replicating in the upper respiratory
tract, it spreads to lymphoid tissues and
eventually spreads throughout the body
 Secondary infections that measles-
infected people are susceptible to
include those of the middle ear and lung
CONTROL
 Young children are vaccinated with
MMR vaccine (pre-school children too)

18. The mumps virus belongs to the family
Paramyxoviridae
It targets the parotid gland, causing painful
swelling of one or both glands
EPIDEMIOLOGY
Humans are the only natural hosts of mumps and
natural infection confers lifelong immunity
PATHOPHYSIOLOGY
 Portal of entry- the respiratory tract
 Multiplies in the tract and local lymph node in
neck and viraemia results
 Symptoms surface only after infecting parotids
and meninges
 It eventually destroys the salivary duct
epithelium and testicular tissue until host’s
immune system eliminates the infection

19. PREVENTION
Most common preventative measure against
mumps is immunization with a mumps
vaccine, invented by Maurice
Hilleman at Merck
May be given separately or as part of
the MMR immunization vaccine which also
protects against measles and rubella
TREATMENT
no specific treatment for mumps
Only symptomatic relief by warm water
gargles, soft foods, extra fluids,
acetaminophen/paracetamol

20. Progressively reduces the effectiveness of
the immune system and leaves
individuals susceptible to opportunistic
infections and tumors
PATHOPHYSIOLOGY
 HIV causes AIDS by depleting CD4+ T
helper lymphocytes
 The mechanism of CD4+ T cell
depletion differs in the acute and
chronic phases:
During the acute phase, HIV-induced cell
lysis and killing of infected cells
by cytotoxic T cells accounts for
CD4+ T cell depletion,
although apoptosis may also be a
factor.
During the chronic phase, the
consequences of generalized immune
activation coupled with the gradual
loss of the ability of the immune system
to generate new T cells appear to
account for the slow decline in CD4+ T
cell numbers.

21. PREVENTION
 Avoiding sexual contact with HIV-infected
individuals
 Avoiding sharing of shaving materials
 Avoiding drug abuse
 Screening of blood before transfusion
 Using condoms during sexual contact
TREATMENT
 Highly Active Anti-Retroviral Therapy
(HAART) – zidovudine, lamivudine, tenofovir
 Azidothymidine (AZT)- for prophylaxis
against progression of disease

23. PATHOPHYSIOLOGY
Herpes is contracted through direct
contact with an active lesion or
body fluid of an infected person Herpes labialis
 Virus enters into susceptible cells
via entry receptors such as
nectin-1, HVEM and 3-O sulfated
heparan sulfate.
 Infected people showing no
visible symptoms may still shed
and transmit virus through their
skin asymptomatically
 Antibodies that develop
following an initial infection with
a type of HSV prevents
reinfection with the same virus
type—a person with a history of
orofacial infection caused by
HSV-1 cannot contract herpes
whitlow or a genital infection
caused by HSV-1

24. Causative Organisms: herpes simplex
viruses, type 1 and 2
 HSV-1: Oropharyngial lesions
 HSV-2 : lesions on Genital mucosa
EPIDEMIOLOGY
 Worldwide in distribution
 No animal reservoirs involved in human
infection transmission
TREATMENT
 DNA synthesis inhibiting drugs
 Vidarabine triphosphate inhibits DNA
polymerase

25. PREVENTION
 Primary prophylaxis: Avoidance of direct
contact with lesion or infected secretions
 Barrier protection
 Anti-virals like acyclovir, valacyclovir
 Vaccination for herpes is the ideal
preventive measure

26. Hepatitis is the term used for any condition where
there is inflammation of the liver
Jaundice and Hepatitis are not the same
A heterogenous group of viruses called
hepatotrophic viruses causes viral hepatitis
and damage to liver:
 HAV – Transmitted by fecal-oral route
 HBV – Transmitted by blood transfusion
 HCV – Post-transfusion Hepatitis
 HDV – Occurs only in HBV-affected
 HEV
The most important type is Hepatitis B

27. HEPATITIS B
EPIDEMIOLOGY
 This disease occurs throughout the world
 HBV causes more than a million deaths
worldwide every year
PATHOPHYSIOLOGY
Involves 3 steps:
1. Entry :
 Blood transfusion
 Sexual transmission
 Infected mother to neonates
 Contaminated syringes and needles
 Rarely by arthropods

28. 2. Multiplication and Spread:
 The HBV target the hepatocytes, integrate their DNA
into host genome and exocytose complete virions
3. Liver cell damage:
 By activation of cytotoxic immune mechanisms
causes cell-degeneration and release of liver-
associated enzymes into bloodstream
PEVENTION
Two types of vaccines currently available:
 Recombinant HB vaccine synthesized from yeast
cells are safe, effective and provides 90%
protection
 Plasma-derived vaccine
TREATMENT
 Interferons in combination with ribavirin – stimulates
body’s defence