Lecture 38 11/25/24 Flashcards
Which arthropod vectors commonly spread arboviruses?
-mosquitoes
-sandflies
-ticks
Which animals serve as reservoirs for arboviruses?
-mammals
-birds
-reptiles
-potentially amphibians and fish
What are the characteristics of arbovirus clinical signs in people?
-very similar across all arboviruses
-flu-like symptoms
-clinical signs can differ with neuroinvasive vs non-neuroinvasive disease
What are the characteristics of west nile virus?
-flavivirus
-closely related to St. Louis encephalitis virus
-cross reacts in many serologic tests
How is west nile virus transmitted?
-mosquitoes**
-transplacental
-breast feeding
-blood transfusion
-organ transplant
-ingestion of infected animal
Which animals develop disease as a result of west nile virus infection?
-humans
-horses
-birds
What are the characteristics of west nile virus in humans?
-5 to 15 day incubation
-80% of infected people are asymptomatic
-can cause neuroinvasive or non-neuroinvasive disease
Which diagnostics are used for west nile virus in humans?
-serology
-virus isolation
-RT-PCR
What are the characteristics of treatment and prevention of west nile virus?
-treatment is based on clinical signs/symptoms
-prevention is primarily mosquito control
What are the characteristics of west nile virus in horses?
-3-15 day incubation
-CNS signs
-30% case fatality rate
-horses are NOT amplifying hosts
Which CNS signs are seen in horses infected with west nile virus?
-depression
-abnormal gait
-tremors
-ataxia
-recumbency
What are the characteristics of diagnosis, treatment, and control of west nile virus in horses?
-diagnosis involves serology, virus isolation, and RT-PCR like in humans
-treatment is symptomatic
-prevention includes mosquito control and vaccination
What are the characteristics of west nile virus in birds?
-amplifiers
-highest mortality in crows, ravens, jays, and owls
-used as surveillance
What are the characteristics of St. Louis encephalitis virus?
-flavivirus
-spread via mosquitoes
-high prevalence in birds
-only causes disease in humans
What are the characteristics of St. Louis encephalitis virus in humans?
-associated with areas of irrigation in the west and southwest
-subclinical infection rates as high as 70% in some areas
-similar clinical signs to west nile virus
How is St. Louis encephalitis virus diagnosed?
serology; must be cautious of cross-reaction with west nile virus
How is St. Louis encephalitis virus prevented?
-mosquito control
-NO vaccines
What are the characteristics of eastern equine encephalitis virus?
-togavirus
-wild birds are the main reservoir; good amplifiers, do not get sick
-disease occurs in humans, horses, and some birds
What are the characteristics of eastern equine encephalitis transmission?
-spread by Culiseta melanura mosquitoes
-found in remote swampy areas
-feed almost exclusively on birds
-bridge vectors feed on infected birds and spread the virus to humans and horses
What are the characteristics of eastern equine encephalitis in humans?
-low ratio of subclinical:clinical cases
-7 day incubation
-case fatality rate of 25-50%
-neurologic sequelae in 50% of survivors in neuroinvasive cases
What are the characteristics of eastern equine encephalitis diagnosis, treatment, and prevention in humans?
-diagnosed via serology
-supportive treatment
-prevention via mosquito control
What are the characteristics of eastern equine encephalitis in horses?
-CNS signs similar to west nile virus, but more severe
-90% case fatality rate
-diagnosed through serology
-symptomatic treatment
-prevented with vaccination
What are the characteristics of eastern equine encephalitis in birds?
-most birds are asymptomatic and act as reservoirs
-causes clinical disease and death in pheasants and emus
What are the characteristics of western equine encephalitis virus?
-togavirus
-wild birds are primary reservoir; amplify, do not get sick
-chickens can be used as sentinels
-found in southern and western states
What are the characteristics of western equine encephalitis virus transmission?
-spread via Culex tarsalis mosquitoes
-found in waste irrigation water in western US
-feed mostly on birds, sometimes larger mammals
-careless irrigation increases mosquito numbers
What are the characteristics of western equine encephalitis in humans and horses?
-children more likely to be symptomatic than adults
-horses present similar to west nile virus
-horses have a mortality rate of 25-50%
What are the characteristics of venezuelan equine encephalitis virus?
-togavirus
-spread by numerous mosquito species
-small mammals act as main reservoir
-mostly seen in Texas and Florida
What are the characteristics of venezuelan equine encephalitis in humans?
-similar to west nile, eastern equine encephalitis, and western equine encephalitis
-low case fatality rate
What are the characteristics of venezuelan equine encephalitis in horses?
-have high viral load; easy transmission to mosquitoes
-possible resp. transmission between horses
-mortality can reach 20-40%
-controlled through mosquito control and quarantine of infected horses
What are the characteristics of LaCrosse virus?
-bunyavirus
-small mammals are reservoirs
-no animals get sick; only humans
What are the characteristics of LaCrosse virus in humans?
-80 to 100 neuroinvasive cases reported annually
-similar symptoms to other arboviruses
-children more likely to develop severe disease
What are the characteristics of denguevirus?
-flavivirus
-4 serotypes
-infection with one serotype does not protect against infection with other serotypes
-sequential infections put people at greater risk for more severe symptoms
-transmitted by mosquitoes, organ/blood transplants, and transplacental
How is denguevirus prevented?
-mosquito control
-vaccines for very specific populations
What are the characteristics of dengue hemorrhagic fever?
-occurs after more common signs
-lasts 24 to 48 hours
-increases permeability of vessels; everything starts leaking
What are the characteristics of chikungunya?
-togavirus
-found worldwide
-transmitted by mosquitoes, blood transfusion, or from mother to child at time of birth
-primates likely reservoir
What are the characteristics of zika virus?
-flavivirus
-spread via mosquitoes and sexual transmission
-illness causes flu-like symptoms, microcephaly, and guillain-barre syndrome
