Mhr Topic 32: Arboviruses

Front 1

Zoonic

Back 1

Animal must be involved in transmission cycle.

Front 2

Vectors

Back 2

Usually arthropods. Host where virus replicates productively and which transmits the virus from one host to another.

Front 3

Maintenance host

Back 3

Host in which the virus replicates productively and from which arthropod vectors can become contaminated with a blood meal. Infections of these hosts is usually asymptomatic.

Front 4

Dead-end hosts

Back 4

Hosts where the virus can replicate to a limited degree but not really significant to maintaining the virus pop. May or may not cause disease. Humans and horses are usually this.

Front 5

Enzootic transmission

Back 5

Normal transmission cycle of a virus between a, arthropod vector and maintenance host.

Front 6

Vertical arthropod transmission

Back 6

transmission of a virus from an infected insect to its offspring via infected eggs. Increases the number of vectors which can disseminate the virus.

Front 7

Epizootic transmission

Back 7

Transmission cycle between an arthropod and a vertebrate thats not normal maintenance host (often a dead end host).

Front 8

Urban epidemic transmission

Back 8

Transmission between human and arthropod and back again. Needs no other animals.

Front 9

3 ways humans can get involved with arboviruses

Back 9

1) Spillover from a enzootic cycle
2) " " " epizootic cycle
3) Self sustaining urban epidemic cycles

Front 10

Togovirus genome

Back 10

SS + unsegmented

Front 11

flavivirus genome

Back 11

SS + unsegmented

Front 12

Bunyaviridae genome

Back 12

SS - 3 segments

Front 13

Are togaviruses, flaviviruses, and bunyaviruses enveloped or naked

Back 13

enveloped

Front 14

Flavivirus replication

Back 14

same as HCV

Front 15

Yellow fever (type, infection)

Back 15

Flavivirus, Mosquito-borne. 2 infection cycles
Jungle - normally between monkeys and mosquitos, then humans get involved.
Urban - Mosquitos and humans only

Front 16

Yellow fever (disease, mech)

Back 16

Jaundice and hemorrhagic fever. Is biphasic
Initial - head and neck flushing, strawberry tongue, fagets sign (fever and brachycardia).
Second - Most cleared by initial. Black vomit, bleeding from punctures, more jaundice, renal failure, shock, death.

Front 17

yellow fever diagnosis

Back 17

Measure anti yellow fever abs or detection of viral antigens.

Front 18

yellow fever treatment/prevention

Back 18

treatment - fluids and antacids
prevention - avoid mosquitoes and vaccine.

Front 19

Dengue virus (type, infection)

Back 19

Flavivirus, mosquitos. Humans are actually the proper maintenance host.

Front 20

Dengue disease

Back 20

Classic dengue fever - aka breakbone fever: flu, with severe muscle/bone pain and arthralgia. Usually recover in a week.
Dengue hemorrhagic fever - Biphasic disease, usually kids <15. Abs against one serotype of dengue cross react with another but dont neutralize, just opsonize making macs eat it. Concentrates viruses in macs where they like to replicate. First phase is classic dengue fever, second is circulatory collapse, hemorrhagic pneumonia, thrombocytopenia. Can be fatal.

Front 21

Dengue diagnosis

Back 21

Symptoms of hemorrhages, thrombocytopenia, possible encephalitis. Can confirm via rc-pcr and sero testing.

Front 22

Dengue treatment/prevention

Back 22

Control shock due to excess bleeding,
avoid mosquitos, vaccine is on the way.

Front 23

Saint louis Eencephalitis virus (type, infection, disease, therapy)

Back 23

Flavivirus
Vector = mosquitoes, Maintenance host = birds often sparrows
Disease more common in adults and more severe in children. Febrile headache to encephalitis, possible death.
No antivirals or vaccines.

Front 24

West Nile Virus (type, infection, disease, therapy)

Back 24

Flavivirus
vector = mosquitoes, maintenance host = birds (sparrows, crows, blue jays).
Disease is more common in adults/elderly. flu-like with rare meningitis and encephalopathy. possible death.
Supportive therapy.

Front 25

Eastern Equine encephalitis virus (type, infection, disease, treatment)

Back 25

Togavirus
Mosquito vector, targets humans and horses (dead end), found on eastern half of country.
Frontal headache, dizzyness, neck stiffness, convulsions, encephalitis. Permanent brain damage can plague survivors.
Supportive therapy including PT and respiratory support

Front 26

Western Equine encephalitis virus (type, infection, disease,)

Back 26

Togavirus
Mosquito vector, targets humans and horses (dead end), found on western half of country.
Convulsions, weakness, encephalitis.

Front 27

La crosse encephalitis virus (type, infection, disease)

Back 27

Bunyavirus
vector = mosquitoes, reservoir = chipmunks and squirrels. Found in Midwest.
Most are subclinical, can get encephalitis.

Front 28

Chikungunya virus (type, infection, disease)

Back 28

Togavirus
vector = mosquitoes, maintenance host = monkeys. Can establish urban cycle.
Fever rash ..... arthralgia, can cause joint problems for years.