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24 Cards in this Set
- Front
- Back
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What are the major viral causes of gastroenteritis and what family are they in?
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Rota viruses (reoviridae) and noroviruses (calciviridae)
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Describe the structure and genome of reoviridae
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They are naked icosahedral with a segmented dsRNA genome
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What are the three important genera of reoviridae?
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Orthoreovirus, rotavirus, and coltivirus
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What is significant about the orthoreovirus?
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It is an infectious virus that has NO disease manifestation (asymptomatic); also known as "respiratory-enteric-orphan virus"
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Describe the EM appearance of the rotavirus; how is it transmitted?
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It looks like a wheel with spokes; it is transmitted via fecal-oral route
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Describe how the colitvirus is transmitted
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It is an arbovirus transmitted by ticks (Colorado tick fever virus)
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What are the symptoms of rotavirus infections in infants and children and what is the peak incidence?
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Fever, vomiting and diarrhea; the peak incidence varies from winter in the southwestern US to spring in the northern and eastern states
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What group has the greatest risk of severe disease caused by the rotavirus?
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6-24 month children
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How is the transmission of rotavirus different from other fecal-oral viruses?
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Rota is transmitted mainly in the winter/spring and most other fecal-oral viruses are summer-fall
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What is a serious complication of the rotavirus infection and how is it treated?
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Dehydration due to major diarrhea, fever, and vomiting; this is treated by oral hydration therapy or IV fluids
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Describe the postulated pathogenesis of rotaviral diarrhea
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The virus infects cells at the tip of the small intestine villi, which are eventually damaged and lost, leaving the immature cells with reduced capacity to absorb water and salts = diarrhea
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What are the important components of the rotaviral vaccines and what type of vaccines are given?
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The vaccines are oral live-attenuated consisting of the RNA segment 9 (for human rota reassorted with animal rota)
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Describe the oral-live attenuated vaccine that was given for rota infections but discontinued; what was the complication?
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This vaccine was a rhesus rotavirus reassorted with human rotavirus VP7 that caused intussusception and was removed from the market
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Describe the currently FDA licensed rotaviral vaccine
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It is a pentavalent oral live-attenuated vaccine made by reassortments of a bovine rotavirus with the dsRNA segment of human rotaviruses which encodes an icosohedral capsid responsible for most antigenic serotypes
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When is the live-oral rota vaccine to be given to children?
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2,4, and 6 months with 1st dose by 12 weeks and 3rd by 32 weeks
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Describe the most recent rota vaccine
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It is an oral live-attenuated MONOvalent vaccine with 2 doses; licensed in 08
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What is the major cause of viral gastroenteritis in older children and adults?
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The norovirus (norwalk-like virus)
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Describe the structure and genome of the norovirus
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It is a naked icosohedral virus with a +ssRNA genome
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What is the major transmission factor of gastroenteritis caused by the norovirus?
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Food-borne illness
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What are the important characteristics of the norovirus (norwalk-like virus) that facilitate their spread during epidemics?
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1) they are transmitted by food/water 2) low infectious dose 3) stable 4) lack of lasting immunity 5) prolonged asymptomatic shedding
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What is the incubation period for norovirus infection?
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24-48 hours
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What is the major symptom of norovirus infection?
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Vomiting with or without diarrhea
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What time of year do norovirus infections generally occur?
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They occur throughout the year at any time
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How are norovirus infections treated?
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There is no therapy but replacement of fluids and electrolytes is important
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