Exam 3: Togaviridae Flashcards
What are the equine alphaviruses?
Eastern equine encephalitis virus* (EEE)
Western equine encephalitis virus* (WEE)
Venezuelan equine encephalitis virus* (VEE)
HIghlands J virus
What is the vector of WEE?
Culex tarsalis
What are the subtypes of VEE that are the most virulent and epidmeic?
I-AB and I-C are virulent strains involved in the epidemics
What is the vector of EEE?
Cluiseta melanura
What is the vector of VEE?
Multiple species involved
Enzootic: Culex spp.
Epizootic: Psorophora spp, Aedes spp
What are hosts of VEE?
Amplifying hosts are wild birds
Hosts include wild birds, equine, and other mammals
When is the seasonal effect of alphaviruses?
Mostly in warm weather
What kind of hosts are humans and horses for alphaviruses?
Dead end hosts- too low viremia
Where are high viremias found?
Virus enters bloodstream via saliva of an infected female mosquito. It targets monocytes and endothelial cells near regional lymph node. The replication process results in a primary viremia which allows virus to invade extra neural tissues. Further replication provides a secondary viremia with much higher virus load. Higher titer of virus in blood stream is necessary for virus to invade CNS
Passerine develop high-titer viremia
Horses do not develop enough viremia to infect mosquito
Epizootic VEEV is virulent to horses with high viremia
What are the clinical manifestations of disease by all of the alphaviruses?
Infection may be subclinical or may present only with fever, anorexia, and depression.
Progressive systemic disease leading to death with minor neuro signs is common in VEEV
Neuro disease is most severe in EEEV
The cerebral cortex, thalamus and hypothalamus are often most severely affected areas of brain with alphavirus infection- can be seen on gross pathology
