Viral GI Diseases Flashcards
Types of Viral gastroenteritis
Rotavirus
adenovirus
caliciviridae (noroviruses)
Virus characteristics
- Obligate intracellular parasites (reproduce in living cells only, no indep. metabolism)
- Small in size (pass through fine pore filters)
- Replicate differently (progeny in assembly line fashion; no binary fission)
Lytic virus-host interaction
virus replicates rapidly to form new virions and may result in lysis and death of cell
Stages of virus replication
- entry
- uncoating
- genome replication
- transcription
- assembly
- Maturation and/or golgi wrapping
- Release
Non-lytic virus host interaction
quiescent interaction
virus remains associated w/ host, but its genes are largely unexpressed (prophage, bacterial lysogen or provirus)
Stable/long term; may be terminated by environmental conditions
Toxins
Persistent infections
infection w/o cell death; unusual virus-host interaction in which virus is found in long-term association w/ host
Latent infections
intermittent acute episodes of virus production b/w which there is an almost total absence of virus particles and very limited viral macromolecular synthesis; Ex.) HSV
Chronic infections
nonlytic production of virus, continued presence of substantial numbers of virus particles during periods in which clinical disease is absent;
Ex.) HBV
Transforming infections
infected host cells are “immortalized” and properties altered (transformed) to those of cancer cells
Ex.) HPV
Gastroenteritis
inflammation of stomach and intestine; frequent cause of mortality in children in developing nations
Sx of gastroenteritis
N/V, diarhea, cramps, malaise, anorexia, myalgia, h/a;
main feature: acute watery diarrhea
Clinical manifestation of gastroenteritis
replication in small intestine epithelial cells (15-48 hrs incubation period); lasts 3-5 days;
virus may be shed at low levels for days- weeks after illness
High risk for gastroenteritis
hospital daycare nursing home immunosuppressed travelers military
Dx of gastroenteritis
antigen detection by enzyme immunoassay (Rotazyme) or latex agglutination screen test
Tx of gastroenteritis
oral re-hydration (Solutions of electrolytes plus sugar like pedialyte) (no abx)
