A Virology 11 Gi

Front 1

Rotaviruses Properties and Replication

Back 1

- 11 pieces of dsRNA -> high rate of reassortment in dual infection(w/in groups not b/w)
- groups share cross reactive Ags (A, B, C in humans, A in US)
- lots of serotypes in each group
- 3 layer icosahedral w/ spikes (must be cleaved to infect)
- cytocidal, replicate in the intestinal epi cell cytoplasm
- use viral encoded enzymes

Front 2

Rotaviruses Pathogenesis

Back 2

- ingested (fecal-oral) -> viruses replicate in the columnar epi of intestines
- villi lose surface epi cells -> malabsorption -> diarrhea
- glycoprotein 4 may be enterotoxin -> diarrhea
- die from dehydration
- no residual damage(cells rapidly ->normal after clearing)

Front 3

Rotaviruses Clinical Signs

Back 3

- subclinical to fatal diarrhea
- infants(<6mo) asymptomatic, maternal antibody
- severe almost exclusively seen in the 6-24 months
- later infections are mild (unless immunocomp/old, but not big in HIV)
- asymptomatic incubation -> vomit for 3days
- fever/diarrhea begins later(lasts up to 1wk)
- give supportive fluid therapy to resolve

Front 4

Rotaviruses Diagnosis

Back 4

- detection of rotavirus (EM of stools), or viral antigen (ELISA or PCR)

Front 5

Rotaviruses Epidemiology

Back 5

- major cause of severe diarrhea everywhere
- mainly kids <2yrs
-cooler months=more freq(in developed)
- first appears in the SW then sweeps NE
- infection from as few as 10 virus particles
- 48 hour asympt incubation, w/ high level of shedding(lasts throughout clinical phase & days after symptoms end
- subsequent infection = subclinical from childhood immunity(exposed to lots, yrs later may re-infect, mildly)
- Aerosol and formite spread
- resistant to inactivation
- can retain infectivity for seven months at Room T
- frequent nosocomial infection

Front 6

Rotaviruses Treatment and Prevention

Back 6

- fluid/electrolytes replacement
- vaccine should prevent severe diarrhea in first 2 years (most critical)
- there was a failed vaccine that was withdrawn(ettenuated rhesus monky rotavirus(ARMR))

Front 7

Norwalk Agent Properties and Replication

Back 7

- calicivirus, naked, (+) sense ssRNA
- fastidious in their growth requirements, replicate poorly in cell culture
- humans only reservoir

Front 8

Norwalk Agent Pathogenesis

Back 8

- villi of the SI broaden and become blunted
- epithelial mucosa remains intact(opp of rotav.), but malabsorption -> diarrhea
- nausea and vomiting due to affected gastric motor function

Front 9

Norwalk Agent Clinical Manifestations and immunity

Back 9

- 24 hour incubation
- lasts 24-48 hours once symptoms begin
- nausea, vomiting(kids), diarrhea(adults)
- no immunity if previous exposure, maybe due to different serotype or genetic # of virus receptors

Front 10

Norwalk Agent Diagnosis

Back 10

- often the diagnosis in GI outbreak if:
1) others have been ruled out
2) more than 50% are vomiting
3) its an epidemic fashion, follows point-source exposure by 24-48 hrs

Front 11

Norwalk Agent Epidemiology

Back 11

- not major cause of infantile diarrhea
- outbreaks in schools, institutions, camps, families
- gets adults and school age children
- epidemics from contaminated shellfish(raw=most freq cause of gastroenteritis outbreaks), food, or water
- 1/3 to 2/3 of GI epidemics

Front 12

Norwalk Agent Treatment and Prevention

Back 12

- oral fluid replacement
- Pepto-Bismol (bismuth salicylate) to reduce symptoms
- just be sanitary to prevent

Front 13

Adenoviruses

Back 13

- do acute respiratory syndromes and epidemic keratoconjunctivitis
- 2 serotypes (of dozens) associated with gastroenteritis
- really only do nosocomial diarrhea in young children