GI Viruses Flashcards
Classification of Norovirus
caliciviridae family. no envelope icosahedral symmetry, ssRNA positive sense
what is noro resistant to
heat acid and ether
How many genogroups of noroviruses are there?
5
What is commonly implicated in noro outbreaks
foods that require handling but not cooking like sandwiches and salads
How many deaths in the developing countries from noro?
200,000 deaths in children <5
How many people have antibodies by age 5 to noro
50%
When is the peak season of noro
cold weather months
what is the transmission route of noro?
fecal-oral
What is the incubation period of noro
18-72 hours
how long does norovirus shed?
usually up to 72 hours after illness… sometimes weeks
How long does noro persist?
2-3 days
What makes one susceptible to noro infection?
H blood group carbohydrate antigens
How does one dx norovirus?
1. lack of PMN's in the stool Labs can do... 1. eletron microscopy 2. enzyme immunoassay 3. PCR
What happens with serology for noro?
Serum IgA, IgM, IgG generated
jejunal IgA seen 2 weeks after infection
Is there long-term immunity to noro?
4-6 months there is resistance, but this wanes over 2-3 years
What correlates with resistance to noro
lack of secretion of H blood roup antigens
What is the tx for noro
supportive. oral fluid replacement… maybe intravenous if necessary
What is the classifcation of rotavirus?
family: reoviridae. non-enveloped icosahedral. dsRNA 11 segments
What is the epidemiology of rota?
Mostly kids (6 mos to 2 years). Infection is universal by 2-3 years
Kills 600,000 kids annually
How is it spread? rota…
fecal-oral spread
What is the incubation period of rota
1-3 days
how long does the illness last?
2 phases
2-3 days of vomiting and fever
4-5 of watery diarrhea
How long does someone shed virus?
4-10 days after resolution of the sx
Is there long term immunity to rota?
reinfection is common, but little or no symptomatology. T cell immunity contributes to infection.
Describe the pathogenesis of rotavirus
thought that NSP4 acts as an enterotoxin which increases calcium and leads to hypersecretion… could be the enteric nervous system
How does one dx rota?
epidemiologically, but the clinical definition is so nonspecific
lab
1. electron microscopy
2. elisa for antigens (only group A)
3. RT-PCR
4. Tissue-culture (remember that noro cannot be grown in culture)
What is the treatment of rotavirus?
oral rehydration and supportiveness. zinc supplementation
What are the vaccines?
rotateq: approved 2006
rotarix: approved 2008
