Vector transmitted viruses

Question 1

List viruses transmitted by insects that are commonly seen in the US

Answer 1

Western equine encephalitis 
Eastern equine encephalitis
St Louis encephalitis
Bunyaviruses ex La Crosse encephalitis
Venezuelan equine encephalitis
Colorado tick fever
West Nile virus

Question 2

List three clinical syndromes associated with insect-transmitted viruses

Answer 2

encephalitis
hemorrhagic fever (dengue, yellow fever)
arhtritis/ arthralgia (chikenguny)

Question 3

List four clinical syndromes associated with animal-transmitted viruses

Answer 3

encephalitis
uremic syndrome (hantavirus) 
pulmonary syndrome (hantavirus)
hemorrhagic fever (ebola, lassa)

Question 4

If the endemic host of a virus is humans, the virus can be maintained through an ____ cycle

Answer 4

urban

ex yellow fever, dengue

Question 5

In the ____ cycle, humans are dead end/ tangential/ incidental hosts

Answer 5

Sylvan

Question 6

Human to human transmission of these viruses is generally (common/ rare)

Answer 6

rare

West Nile Virus is the exception- transmitted through blood transfusions

Question 7

List three ways vector-borne viruses can be maintained in nature

Answer 7

• hibernating small animals
• transovarial transmission in ticks/ mosquitoes
• asymptomatic animal hosts with chronic infection

Question 8

What is the general pathogenesis of arboviruses?

Answer 8

Arboviruses are introduced directly into the blood by an infected arthropod. The virus
replicates in the reticuloendothelial system and vascular endothelium. A secondary viremia may then seed target organs.

Question 9

In West Nile and other encephalitis viruses, _____ results in seeding of the CNS leading to direct damage to nervous tissue as well as host immune damage

Answer 9

secondary viremia

Question 10

In _____, damage to the liver leads to loss of clotting factor production and bleeding

Answer 10

yellow fever

Question 11

In hemorrhagic fever, there is both direct cell damage to the _________ and damage caused by host immune response

Answer 11

vascular endothelium

Question 12

The presence of a non-neutralizing antibody leads to ______ as seen in dengue (infection of cells that would not normally be infected)

Answer 12

immune ehancement

Question 13

Hantavirus pulmonary syndrome is caused by inhalation of _____ and targets the ____

Answer 13

rodent droppings

lungs- pulmonary edema

Question 14

The ebola envelope ____ is toxic to vascular endothelial cells

Answer 14

glycoprotein

Question 15

Rabies causes a distinct cytopathic effect called the ____ body, an eosinophilic inclusion body

Answer 15

negri

Question 16

How are insect vector diseases normally diagnosed?

Answer 16

serology using acute and convalescent sera

can use culture but less common

Question 17

How are animal vector diseases diagnosed

Answer 17

may need a reference lab ex CDC

usually only by serology

Question 18

What treatments are available for vector borne viral disases

Answer 18

supportive care
NOT steroids
ventilatory support as needed
no effects with ribavirin, interferon in vivo
Rabies- give vaccine and Ig ASAP