3. General properties of
Arbovirus
All members produce fatal encephalitis in 48 hr old suckling mice
1-10 days after intracerebral inoculation.
They possess haemagglutinin for RBCs of newly hatched chicken.
After oral feeding, mosquito-borne arbo viruses multiply in Aedes
and Culex mosquitoes.
Tick-borne arbo viruses multiply in Ioxodid ticks.
3
4. Classificatio
n
Around 450 viruses are included under arbo viruses
(arthropod-borne)
5 families (infection in human)
Togaviridae
Flaviviridae
Buniaviridae
Reoviridae
Rhabdoviridae
4
6. Japanese B encephalitis
First discovered and originally restricted to Japan. Now large
scale epidemics occur in China, India and other parts of Asia
The virus was named Japanese B encephalitis virus to distinguish
it from Japanese A encephalitis virus
Transmitted by Culex tritaeniorhynchus mosquitoes
The virus is maintained in nature in a transmission cycle involving
mosquitoes, birds (reservoirs) and pigs (amplifier hosts)
6
8. Incubation period: 5-15 days
The course of the disease in man may be divided into three stages
1.Prodromal stage: fever, headache and vomiting
2.Acute encephalitic stage: signs of encephalitis characterized by
neck rigidity, convulsions, altered sensorium and coma
3.Late stage and sequelae: Residual neurological damage
8
Sign And Symptoms
10. Prevention And Control
Preventive measures include mosquito control and establishment
of piggeries away from residential areas
A formalin inactivated mouse brain vaccine using the Nakayama
strain has been employed for human immunization
A live attenuated vaccine prepared in hamster kidney cell line
is also available
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12. Yellow fever
Yellow fever is a mosquito-borne acute febrile illness
accompanied by hepatic necrosis
It occurs mainly in tropical Africa and Latin America
It does not exist in India and Nepal
The name has been derived from ‘yellow quarantine flag’
Yellow fever occurs in 2 major forms: urban and jungle.
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13. The virus being transmitted by Aedes aegypti mosquito
13
Mode of Transmission
14. Incubation period of 3-6 days,
Patient develops fever with chills, headache, myalgia and
vomiting
The pulse is usually slow despite a high temperature
Serious form of disease with jaundice, albuminuria, renal failure
and haemorrhagic the patient may die of hepatic and renal failure
14
Sign And Symptoms
15. There is no antiviral drug against yellow fever
The control yellow fever can be achieved by eradicating
the vector mosquito
Two vaccines have been developed for human use
1.The french neurotropic vaccine (Dakar) produced from
infected mouse brain
2. 17D vaccine developed by Theiler in 1937
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Prevention And Control
17. Dengue
Virus
The word dengue is derived from the Swahili Ki denga pepo
meaning a sudden seizure by a demon
Dengue fever is clinically similar to the illness caused by the
chikungunya and O’nyong-nyong viruses
Dengue virus is widely distributed in the Caribbean region, south
east asia
Primarily a daytime feeder
Lives around human habitation
17
18. Dengue is transmitted bite of the female mosquito (Aedes aegypti)
18
Mode of Transmission
19. The disease may occur in two forms
1. Classical dengue fever (break-bone fever)
2. Dengue in more serious forms with hemorrhagic manifestations
19
Sign And Symptoms
20. Fever, or recent history of acute fever
Hemorrhagic manifestations
Low platelet count (100,000/mm3 or less)
Objective evidence of “leaky capillaries:”
Skin hemorrhages:petechiae, purpura, ecchymoses
Gingival bleeding
Nasal bleeding
Gastrointestinal bleeding:
Hematemesis, melena, hematochezia
Hematuria
Increased menstrual flow 20
Sign And Symptoms
21. Control measures include elimination of mosquitoes
No effective vaccine is available
There is no specific antiviral treatment
The management is essentially supportive and symptomatic
Bed rest is advisable during the acute febrile phase
Antipyretics or cold sponging should be used to keep the body
temperature < 40C
Analgesics and mild sedation may be required to control pain
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Prevention And Control
22. ADENOVIRUS
Adenovirus is a double stranded DNA viruses having icosahedral
symmetry
No envelope
Family of (Adenoviridae) is a DNA viruses originally identified
in human adenoid tissue,causing infections of the respiratory
system, conjunctiva, and gastrointestinal tract, and including some
capable of inducing malignant umors in experimental animals.
Many adenovirus infection are subclinical and virus persist in
hosts for months
22
23. Adenoviruses are usually spread from an infected person to
others through
Close personal contact, such as touching or shaking hands
Coughing and sneezing
Touching an object or surface with adenoviruses on it, then
Touching your mouth, nose, or eyes before washing your hands
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Mode of Transmission
25. Hand washing before and after handling material an infected person.
Alcohol-based hand sanitizers
Covering mouth and nose with a tissue when coughing or sneezing
helps prevent spread of the virus.
Keeping swimming pools adequately chlorinated.
Avoiding sharing towels and utensils etc. with an infected person.
Avoidance of close contact with a person ill with adenovirus
infection.
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Prevention And Control
26. Respiratory Syncytial
Virus
Respiratory syncytial virus is a member of the Pneumovirus
genus of the family Paramyxoviridae .
The virus is an enveloped, non-segmented virus containing a
single negative-strand of RNA.
RSV is the most common virus causing respiratory infections in
children and almost by the age of 2 years
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27. RSV is spread via direct contact
Contaminated hands, surfaces, and respiratory secretions
Unprotected coughing and sneezing
27
Mode of Transmission
29. Routine hand washing
Careful handling of contaminated materials
Limit contact with hospital visitors
Oxygen supplementation
Antibiotics – given for suspected bacterial
Nebulized hypertonic saline
Ribavirin is the only approved drug for the treatment of severe
RSV.
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Prevention And Control
