Arthropod and Rodent Borne Viruses

Question 1

what is an arbovirus ?

What is a zoonosis?

Answer 1

Arbovirus – arthropod borne virus

Zoonosis – any pathogen of animals that is transmissible to humans

Question 2

What viruses are Arthropod borne ?

Virology:

Answer 2

Flaviviruses:
Yellow Fever
Dengue Fever

Enveloped,
positive sense SS RNA

Cytopasmic Replication

Question 3

Yellow fever:
Reservoir
Transmission – cycles?

Answer 3

transmitted by Aedes Mosquito
Reservoirs: Humans and Monkeys

Urban and Sylvan Cycles

Urban spread: Mosquitoes infect human to human

Sylvan Spread: Mosquitoes infected monkey to human

Question 4

yellow Fever: 
Clinical presentation 
Diagnosis 
Treatment? 
Prevention ?

Answer 4

Sx: abdominal pain, high fever, vomiting;

Tropism for the liver – jaundice
Hemorrhage of the GI
“black vomit” - hematemesis

Abnormal Coags
Liver Failure; kidney failure

Seizures, shock, death
50% fatality

Dx: PCR

Prevention: Live attenuated Vaccine

Question 5

Dengue Fever

what is the first infection like?

Answer 5

Dengue Fever – may be asymptomatic, or have Fever, HA, malaise, chills, retro orbital pain, petechial rash

Question 6

Dengue fever -

why is a repeat infection more severe than the first infection? Describe the mechanism and clinical presentation

Answer 6

a repeat infection by another serotype: more severe due to Anti-body dependent enhancement:

Dengue hemorrhagic fever; dengue shock syndrome

Antibodies have been formed following the first infection. Cross react, but instead of neutralizing the virus, it is redirected towards infection of monocytes and macrophages —> cytokine amplification –> increased severity and mortality

Question 7

Dengue fever -

Diagnosis
Treatment
Prevention

Answer 7

Serology PCR

No treatment

Prevention – no vaccine; avoid mosquito bites

Question 8

What are the Rodent Borne viruses?

Answer 8

Hantavirus – Bunyaviridae

Lassa Fever – Arenaviridae

Question 9

Hantavirus -
describe the virology
(what family is it in?)

what is the reservoir?
How is it transmited?
where was the last outbreak

Answer 9

Bunyaviridae –
Enveloped
Negative sense RNA
Segmented; 3 segments

Reservoir: Deer mouse

Transmitted: contact with secretions; feces; aerosols; bites

Outbreaks in campers in national parks, and indian reservations

Question 10

what are the clinical manifestations of hantavirus ?

Answer 10

Hantavirus Pulmonary Syndrome

Fever, myalgia, weakness, cough, SOB,
Backache, dizziness, abd pain
Respiratory distress

40% Mortality

Question 11

Lassa Fever
virology? (what family is it in)

What is the reservoir
how is it transmitted
where is it endemic?

Answer 11

Areanviridae
Enveloped
ss Negative sense RNA
segmented - 2 segments

Reservoir: House Rats (Mastomys)

Transmitted: exposure to rat droppings

Endemic: Africa (300K infectins per year)

Question 12

Lassa Fever: 
- Clinical presentation 
who is most susceptible/highest mortality 
- Dx; 
Treatment; 
PRevention

Answer 12

Fevers chills
Viral hemorrhagic Fever
15-20% Mortality
Higher death rates in 3rd trimester women and fetuses

Dx: serum Ag, RT, PCR

Treatment: Ribavirin

No vaccine

Question 13

Filoviridae

• virology: (what family)
• how many proteins are produced? what is the special funciton of 2 of them ?

Answer 13

Ebola and Marburg virus
- Enveloped
Filamentous
ss, negative sense RNA

7-8 proteins; 2 of which are Interferon antagonists

Question 14

Filoviridae

• Reservoir
• Transmission

Answer 14

reserovir – thought to be bats
unknown how transmission occurs from bats to humans

Person to person transmssion via close contacts

Question 15

Filoviridae

- clinical presentation

Answer 15

Fever, malasie, diarrhea; hemorrhage;

Human mortality can exceed 90%

Elevated liver enzymes; platelets may plummet

Severe multisystem dysfunction

Vascular system is damaged; accompanied by hemorrhage

Question 16

what viruses can cause viral hemorrhagic fever:

Answer 16

Bunyavirus (Hanta)
Arena (Lassa Fever)
Filoviridae (marburg and ebola)
Flavivirous (yellow and dengue

Question 17

Chikungunya Virus

• Virology
• vector?
• clinical presentation?

Answer 17

Positive sense RNA
Mosquito

Polyarthralgia, maculopapular rash, fever