Togaviridae Flashcards
Togaviridae causes severe disease in what two species?
humans
horses
Is togaviridae enveloped?
yes
In togaviridae, each spike are a trimer of what two proteins?
E1 and E2
*supports proteins on the lipid envelop
In togaviridae, the RNA codes for what two polyproteins?
non structural and structural
Togaviridae is present in the host cell within a ____
vesicle
What polyproteins initiate the replication of the positive RNA virus during Togaviridae replication?
P1234
P123 + naP4
What three cycles maintain arboviruses?
Urban cycle
Enzootic cycle
Epizootic cycle
What is the most important arbovirus cycle for infection of humans?
Urban cycle
What arbovirus cycle is maintained between a primary vector and domestic animal?
Epizootic cycle
What is a vector called that can trasmit a disease from one cycle to another?
bridge vector
Who is the dead end host within the arbovirus cycles?
humans
Who is the primary vector within the enzootic (sylvatic) arbovirus cycle?
arthrophod vector
Eastern equine encephalitis virus is a zoonotic disease transmited by ____
mosquitos
Eastern equine encephalitis virus is caused by what genus of togaviridae?
Alphavirus
What is the main genus of togaviridae?
alphavirus
Eastern equine enchaphalitis causes _____ in horses and humans
encephalitis
How many lineages are there in eastern equine encephalitis and which one is the most virulent?
4 lineages
group 1 is the most common in the US and most virulent
What weather is eastern equine enchephalitis associated with?
heavy rainfall
*swamp areas
What are the two cycles that maintain eastern equine encephalitis?
epizootic cycle
enzootic cycle
In the epizootic cycle of eastern equine encephalitis, _____ can be infected by mosquitos and transmit the virus among themselves
pheasants
____ mosquito acts as the bridge vector in eastern equine encephalitis and can transmit the virus to birds and humans
Aedes
The enzootic cycle of eastern equine encephalitis is maintained by wild birds and what species of mosquito?
Culliseta melanura
Eastern equine encephalitis induced apoptosis of what cells?
neuronal and glial cells
_____ infection is the most common with eastern equine encephalitis in horses
inapparent/mild
If a horse develops clinical signs with eastern equine encephalitis, what would they be?
walks blindly into objects
paralysis
incoordination
inability to hold up the head
What are some pathologies associated with eastern equine encephalitis in horses?
brain hemorrhage
necrotizing vasculitis
death
What does eastern equine encephalitis cause in humans?
systemic form- fever, malaise, no CNS involvment
encephalitis form- Fever, vomiting, convulsions, coma, unlitmately patient my die
*most cases have no apparent illness
What is the prognosis for eastern equine encephalitis in humans?
1/3rd of all people with disease will die
recovered patients may have brain damage
What region of the US is Western equine encephalitis found?
Western
What are the two forms of western equine enchephalitis and which one is more virulent?
epizootic- more virulent
enzootic
True/False: western equine encephalitis is more virulent than eastern equine encephalitis
False
There is a lower fatality rate with wester equine encephalitis
True/False: Western equine encephalitis tends to cause epidemics in ares of disease
False
Causes sporadic individual cases
What two animals play a role in the enzootic (primary) cycle of western equine encephalitis?
bird- reservoir
mosquito (CULEX)- main vector
What ampilification hosts are involved in the epizootic (secondary) cycle of Western equine encephalitis?
rodents
black tailed jack rabbits
What mosquito species is the vector for the epizootic cycle of western equine encephalitis?
Aedes
While most cases of Western equine encephalitis are asymptomatic, what are some clinical signs in horses during a severe case?
fever
blindess
paralysis
death in extereme cases
What age group of humans have the highest suscpetibility to western equine encephalitis?
infants and children
*young patients are often left with brain damage
*asymptomatic in adults
How many subtypes of Venezuelen equine encephalitis exist and which ones are virulent?
6 subtypes
1-A, 1-B, and 1-C are highly virulent in equines (epizootic)
What is the vector and amplification hosts for the enzootic cycle of venezuelan equine enchephalitis?
vector host- Culex mosquito
aplification host- rodent
In western equine encephalitis and eastern equine encephalitis both humans and horses are ______
dead end hosts
*cannot trasmit the disese
What animal is the dead end host in the enzootic cycle of venezuelan equine encephalitis?
horses
Who is the amplifying host, primary vector, and dead end host in the epizootic cycle of venezuelan equine encephalitis virus?
primary vector- mosquito
amplification host- horses (virus can replicate at high titer in horses)
dead end host- human
Sometimes in venezuelan equine encephalitis, the _____ strain of the virus can mutate into the _____ strain
endemic can mutate into the epidemic
*less virulent form can become very virulent
What clinical signs are associated with venezuelan equine encephalitis in horses?
head hung low
incoordination
death
encephalomyelitis
leaning
In humans, venezuelan equine encephalitis is normally an ____ disease
acute, systemic
*Causes very important disesae in humans such as encephalitis and can cause abortion in pregnant women
What are some ways to diagnose equine encephalitis?
detection of antigen- ELISA
isolation of organism
necropsy
PCR
What is the best way to control equine encephalitis?
control of mosquito population
*get rid of stagnant water
What does surveillance of equine encephalitis entail?
trapping mosquitoes and wild animals and testing for virus
Chickens kept in endemic area and tested periodically for virus
What biological control method can be used for control of equine enephalitis?
increase population of predatory fish (Gambusia) that feed on mosquito larvae
_____ can be sprayed in stagnant water to decrease mosquito population
larvicides
EEV, WEEV, and VEEV vaccines are available for horses, however there is no effective vaccines in case of _____
humans
