Viral Encephalitis Flashcards
What is the definition of encephalitis?
Inflammation of brain
What is the definition of meningoencephalitis?
Inflammation of brain and meninges
What is the definition of encephalomyelitis?
Inflammation of brain and spinal cord
What are symptoms/signs of encephalitis?
Depressed or altered level of consciousness, changes in personality or ataxia PLUS One or more of the following: - Fever - Seizures - Focal neurological deficits - CSF pleocytosis
What are major viral causes of encephalitis?
Enteroviruses, HSV, other herpes viruses
What family is West Nile Virus in?
Flaviviridae
What are characteristics of genome/structure of Flaviviridae?
ss (+) RNA
pH dependent uncoating
Replicates in cytoplasm
Virus assembles at ER/Golgi
How is West Nile virus transmitted?
Mosquito (Culex)
Rarely blood transfusion, or verticl
What cytokine may help facilitate neuroinvasion with West Nile virus?
TNFalpha
What is clinical presentation of West Nile virus?
80% asymptomatic
20% non-secific febrile illness
~1% neuroinvasive disease (encephalitis or encephalomyelitis)
What is the reservoir for West Nile?
Birds
In what population is there highest incidence of neuroinvasive disease and highest mortality due to WNV?
elderly
What is a flavivirus very similar to WNV?
St. Louis Encephalitis virus
What family does Eastern and Western Equine encephalitis viruses fall in?
Togaviridae
What are characteristics of genome/structure of Togaviridae?
Nonsegmented
(+) ss RNA
What is clinical presentation of EEEV?
Abrupt onset shills, fever, malaise, arthralgia, myalgia
Encephalitis develops later
Higher mortality in encephalitis patients
What is clinical presentaiton of WEEV?
Asymptomatic or mild systemic illness with fever, malaise, myalgia
Small number develop encephalitis later
Lower mortality in encephalitis patients
What family does La Crosse (california) virus fall in?
Bunyaviridae
What are characteristics of genome/structure of Bunyaviridae?
Enveloped Segmented (-) ssRNA Replicates in Cyoplasm Assembles at Golgi
What are clinical manifestations of La crosse virus?
Fever, headache, nausea, vomiting, fatigue, lethargy
Neuroinvasive (encephalitis) more common in children
Seizures common
Low mortality
What transmits La crosse virus?
Mosquito from small mammals (chipmunks, squirrels)
What family does Rabies virus fall in?
Rhabdoviridae
What are characteristics of genome/structure of Rhabdoviridae?
Enveloped
(-) ss RNA
Bullet-shaped
What is the pathogenesis of Rabies?
Enters muscle cells, replicates slowly
Enters motor nerve, travels rapidly via retrograde transport to spinal cord
Virus spreads rapidly through spinal cord and brain
Virus disseminates via PNS throughout body including skin, salivary glands, heart
What is the histopathological hallmark of Rabies?
Negri bodies in neurons
If you generate effective neutralizing antibodies to Rabies, why are they not protective?
Antibody response doesn’t begin until after infection of CNS
Too little too late
What animal do most cases of rabies come from worldwide?
Dogs
What animal do most cases of rabies come from in US?
Bats
What are clinical manifestations of rabies?
Incubation period - symptom free
Prodrome and early symptoms: fever, malaise, pain, or paresthesia at bite site
Acute neurologic disease
Death
What symptoms are included in the acute neurologic disease caused by rabies?
Agitation, delerium, hallucinations, bizarre behavior, hydrophobia
Autonomic dysfunction: tachy-bradycardia, hyper-hypotension, excessive salivation and sweating, pupillary dilation
Muscle spasms, myoclonus, seizures
How is rabies diagnosed?
Direct flourescent antibody from skin biopsy
PCR
What is treatment for rabies?
Wound care
Call public health authorities
Passive immunization with rabies immunoglobulin
Active immunization with series of IM rabies vaccine injections
