export_cns zoonotic viruses Flashcards
Zoonoses
Diseases of invertebrate animals that can be transmitted to man
Arboviral disease
Involves an insect vector for transmission
Arbovirus examples
Flaviviruses - West Nile, St. Louis and Japanese encephalitis
Togaviruses - Eastern, Western, Venezuelan equine encephalitis
Bunyaviruses - LaCrosse encephalitis
Viruses transmitted to humans directly from other mammals
Rhabdoviruses - rabies
Arenaviruses - lymphocytic choriomeningitis
Flaviviruses transmission
All by mosquitos
West Nile Virus (WNV) reservoirs
Birds serve as reservoirs
WNV symptoms
Most infections are mild and clinically unapparent
Some develop West Nile fever (3-6 days of symptoms)
Sudden onset of febrile illness (malaise, nausea, vomiting, rash)
WNV in the CNS
Primarily affect elderly
Encephalitis and meningitis
Fever, headache, weakness, GI disturbances, may progress to coma and paralysis
Diagnose WNV
Adults >50 years old who suddenly develop encephalitis or meningitis in summer/early fall
WNV treatment
Supportive
St. Louis encephalitis virus (SLE) disease
Major cause of arbovirus encephalitis
SLE transmission
Birds are reservoir
Humans get it from Culex mosquitoes
SLE symptoms
Sudden onset
Fever with headache (mild)
Headaches, high fever, stiff neck, coma, tremors, spastic paralysis (severe)
SLE diagnosis
Confirmed via serology
SLE treatment
Supportive
Japanese encephalitis virus disease
Leading cause of viral encephalitis in Asia
Birds and livestock are reservoirs
Togaviruses transmission
Horses are a major reservoir
Transmitted via mosquito bite
Togaviruses diseases
Eastern equine encephalitis (EEE)
Western equine encephalitis (WEE)
Venezuelan equine encephalitis (VEE)
EEE symptoms
Sudden onset of fever, muscle pain, and headache
Many progress to seizures/coma
WEE symptoms
Most people are asymptomatic or mild
May have sudden onset fever, headache, nausea, vomiting, malaise
VEE symptoms
Most infections are symptomatic
Fever, chills, headache, nausea, vomiting, may progress to encephalitis
LaCrosse encephalitis (LAC) virus transmission
Arbovirus
Transmitted by the bite of infected mosquitoes
LAC symptoms
Fever, headache, nausea, vomiting
Severe disease can lead to seizures, coma, paralysis
Rhabdovirus transmission
Through infected saliva via bites (dogs, bats)
Rabies lifecycle
Inoculation, local proliferation, enters PNS, travels to CNS, dissemination
Rabies symptoms
During cerebral infection, behavioral changes occur (anxiety, confusion, agitation, hallucination)
Hydrophobia is a classic sign
Coma and death
Rabies prevention
Vaccination of animals and high risk individuals
Rabies diagnosis
Disease in animals can be confirmed post-mortem by the presence of Negri bodies
Arenavirus CNS disease
Lymphocytic choriomeningitis virus (LCMV)
LCMV reservoirs
Rodent-borne virus
LCMV symptoms
Most infections are asymptomatic or produce a mild febrile illness
Can cause aseptic meningitis, encephalitis, or meningoencephalitis
LCMV transmission
Inhaling infectious aerosolized particles of rodent urine, feces, or saliva
Most common is the common house mouse
LCMV symptoms
Febrile illness
Biphasic - 1 week of fever, malaise, headache, nausea, vomiting, remission for a few days, then second phase of disease (meningitis or encephalitis)
Prions diseases
Slow developing neurodegenerative diseases, thought to be caused by a family of viruses known as “slow viruses”
Human spongiform encephalopathis
Kuru
CJD
GSS
FFI
Prion features
Lack nucleic acid
Consists of protease, heat and chemically resistant hydrophobic glycoprotein (PrP)
PrPc
Normal cellular prion-related protein
Extended conformation containing numerous alpha-helices
PrPSc
Infectious form of PrPc
Globular conformation with beta-pleated sheets
Theory for Prion replication
PrPSc binds to PrPc on cell surface
Induces conversion to PrPSc
Cycle repeats
Aggregates form, internalized by neurons
Symptoms of Prion infiltration to CNS
Neuronal vacuolization
Astrocyte and glial cell proliferation
Amyloid plaques
Prions clincal syndromes
Slow, progressive neurological degeneration
Very long incubation period
Death ensues rapidly (months)
Prion diagnosis
Postmortem histological examination