This document discusses arboviruses, which are viruses transmitted by arthropod vectors such as mosquitoes, ticks, and sand flies. It notes that arboviruses require both a vertebrate host and arthropod vector to be maintained in nature. The document groups major human pathogenic arboviruses into three families and describes their morphology. It then discusses the transmission cycle involving vectors and hosts, as well as less common transmission routes. The document outlines the pathogenesis of arbovirus infection and resulting clinical features like fever, rashes, and hemorrhagic, encephalitic, or arthralgia syndromes. It provides dengue virus and yellow fever as examples and discusses laboratory diagnosis and prophylaxis

1. Arbovirus
Samita kc
Bachelor of public health
1st semester

2. Introduction
• Arboviruses = Arthropod born viruses .
• These viruses require the presence of vertebrate
host and arthropod vector usually mosquitoes ,
ticks or sand flies .
• In the natural environment the virus is
maintained in a cycle that involves the vertebrate
host and the vector .

3. Contd…..
 These viruses multiply inside the vertebrate host as
well as the vector .
 The vector transmits the disease to human and other
mammals , through the bite .
 Man generally plays no role in the natural history of
arboviruses .
 Humans are not the natural reservoir of this virus.

4. Morphology
• There are hundreds of arboviruses, many of
which are not pathogens to human .
• Human pathogens arboviruses are grouped into
three viral families :
• 1- Togaviridae .
• 2- Bunyaviridae .
• 3- Flaviviridae .
• Arboviruses are enveloped, with ss-RNA genome

5. Contd….

6. Transmission
• Humans are infected through the bite of
infected vector , or when they come into
contact with infected host .
Vector : Mosquitoes, ticks or sand flies .
• Vertebrate host : Mammals and birds.
• Blood transfusion,organ transfusion.
• Mother to child is also obsrved rarely.

7. Pathogenesis
• When vector fed the blood of vertebrate,virus
present in salivary gland comes in contact
with host blood.
• The process of viral replication takes place
inside blood known amplification.
• The virus replication hence causes viraemia
with other clinical features.

8. Contd…
• Other clinical symptom results endothelial cell
damage and replication of virus in endothelial
cell causing secondary viraemia infecting
target organ as skin, muscles, liver, brain.
• Virus may reach upto brain by infecting small
blood vessels of brain or choroid plexus.

9. Clinical features
• Symptoms appear within 2-15 days of
exposure. They are as:
• Fever
• Malaise
• Fatigue
• Rashes
• Sometime it may develop haemorrhagic
fever,encephlitis and meningitis.

10. Contd…
• Arbo virus produces 3 typical clinical
syndromes. They are as:
• Arthralagia syndrome
• Haemorrhagic syndrome
• Encephalitis syndrome

11. Dengue virus
• It is the typical example of Arthralagia
syndrome with the following clinical features:
• Flu like illness with headache, chills, reticular
pain, conjunctivitis
• Break bone fever with severe muscular pain
• Measles like rashes

12. Yellow fever
• It is a typical example of hemorrhagic fever. It
is an acute febrile disease characterised by
degeneration of liver, kidney, heart and
haemorrage.

13. Encephalitis fever
• Here the illness starts with flu like symptoms
as
• Fever
• Chills
• Headache
• Watery eyes

14. Lab diagnosis
• Serological test can be carried out as:
• ELISA
• Complement fixation
• PCR
• Neutralization test

15. Prophylaxis
• Vector controlling method should be applied.
• Chemicals can be used for control as
organophosphates and organochloride.
• Chemotherapy can be used to treat the
underlying symptoms.

16. Contd…

17. THANK YOU……THANK YOU