32 - Viral Infections Flashcards
(37 cards)
Should you treat a suspected viral meningitis with antibiotics?
always. they appear similar.
What are CSF findings for bacterial meningitis?
low glucose
high protein, WBC and neutros
cloudy
What are most common causes of viral meningitis?
enterovirus: echo, coxcacki, entero71
mumps
recurrent aseptic meningitsL HSV2, HIV, VZV
Most common causes of viral encephalitis?
aborviruses: (via ticks/mosquits seasonally)
enteroviruses: family epidemics via URI/GI (oralfecal)
HSV-1 (temporal lobe)
Which HSV is likely to cause encephalitis? Which one for menigitis?
HSV1 for encephalits
HSV2 for recurrent meningitis
What opportunistic infections of the CNS are common with AIDS?
toxoplasmosis, crypto, TB JCV (PML), CMV
What CNS neoplasms can arise with AIDS
primary CNS lymphoma or metastatic kaposi’s
Characteristics of flaviviridae?
enveloped, nonsegmented, +RNA
What are the 3 genera of flaviviridae we know?
flaviviruses: st louis, west nile, japanese encV
Pestivirus: cow, pig, sheep
HCV
What is replication cycle for flaviviridae?
enter via receptor mediated endocytosis.
translation of +RNA by host ribosomes
single polyprotein cleaved by viral and host proteases
viral polymerase replicates genomic RNA
assembly of capsid and envelope
bud into ER/golgi and leave with envelope
What is transmission of flaviviridae?
insect bites. Humans are not the primary host.
What is clinical syndrome for st louis encephalitis?
cough, fever, ehadache sore throat
4 days later subacute meningeal/neuro signs
50% dead in the week, 80% dead in 2 weeks.
Most don’t progress to encephalitis though.
What is course of west nile virus?
1% of bitten infected.
most are mild disease with fever, headache, muscle ache, rash and lymphadenopathy.
Some progress to meningitis symptoms with stuor and convulsions –> coma death
Is there a vaccine for Japanse encepahlitis?
yes and travellors staying for longer than 1 month should get it in asia, india, soviet republic
Characteristics of togaviridae?
enveloped, nonsegmented, RNA+ virus
What are the two genera of togaviridae?
rubivuruses: rubella
alphaviruses: western, eastern, and venzuelan equine viruses
What is replication cycle for togaviridae?
enter cell via receptor-endocytosis
RNA+recognized as mRNA and polymase trnaslated first.
RNA- made, and serves as template for genome and subgenomic polyproteins
Clinical course of alpha virus?
most commonly asymptomatic, but can cause encephalitis.
alpha virus replicates in muscle/fibroblasts of many organs
2 weeks later, encephalitis and death few days later.
What is preventative method for alpha viruses?
vaccinate horses and lab workers. No standard population vaccines.
Characteristics of bunyaviridae?
enveloped, segmented, spherical negative ssRNA.
What are two genera of bunyaviridae?
california encephalitis
lacross encephalitis
Replication cycle of bunyaviridae?
similar to influenza except replication occurs in cytoplasm.
Clincial course of lacrosse?
seizures with focal signs = low mortality
What is most common cause of pediatric encaphlitis in US?
LaCrosse encephalitis virus
