ICL 1.5: Gastrointestinal Viruses Flashcards
what must GI viruses overcome to survive and cause an infection?
- acidic environment of stomach
- bile salts of upper small intestine
- penetrate mucus coating of gut to bind receptors
what is gastroenteritis?
inflammation of the stomach, small and large intestines
GI infections are 2nd major cause of infectious morbidity worldwide
which cell type do GI viruses infect?
- villus enterocytes = non-dividing, absorptive
- crypt cells = dividing, secretory Cl-
enterocytes are on the outside and crypt cells are father in
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what is malabsorption?
loss of enterocytes by direct infection.
what is secondary malabsorption?
loss of enterocytes secondary to loss of crypt cells
crypt cells slowly divide and migrate up villus to replace enterocytes
what do gut bacteria do?
there’s 500 different species living in your gut
they aid digestion and regulate gut inflammation
they also protect host from pathogenic bacteria
which virus families cause AVG?
AVG = acute viral gastroenteritis with diarrhea and vomitting
- rotaviruses
- enteric adenovirus type 40, 41
- caliciviruses (sapoviruses, noroviruses)
- astroviruses
what are non-enteropathogenic viruses?
viruses that infect the gut but are not pathogenic in the gut
which virus families are non-enteropathogenic viruses?
- enteroviruses
- cosaviruses
- reovirus
- adenoviruses
viruses that infect the gut but are not pathogenic in the gut
what are opportunistic viruses?
viruses that happen in immunosuppressed hosts
ex. HIV infection of gut with diarrhea or weight loss
what is the incubation of AVG?
1-3 days
how is AVG spread?
fecal-oral spread or possibly respiratory route
fecal-oral route is a route of disease transmission, when the pathogens infecalparticles passing from one host are introduced into theoralcavity of another host
what are the symptoms of AVG?
- abrupt onset of vomiting (1-3 days)
followed by frequent, copious, watery brown stools (5-8 days)
in severe cases, clear stools (rice water stool)
- low grade fever
- projectile vomiting
- epidemic or sporadic outbreaks
what is a major complication of AVG?
dehydration
there’s so much vomitting and diarrhea so people get dehydrated
how do you prevent AVG?
hand washing
what are some of the presenting symptoms of rotavirus?
rotavirus causes AVG = acute viral gastroenteritis with diarrhea and vomitting
- vomiting
- watery diarrhea
- fever
- sudden onset
which population does rotavirus most often effect?
little children
older children have milder diarrhea
what is the structure of the rotavirus?
naked, segmented dsRNA virus
reoviridae family
what does the rotavirus cause?
originates from the hospital!!
it’s a major agent of gastroenteritis and dehydration
what causes diarrhea in rotavirus?
viral nsP4 protein
it’s a viral enterotoxin that causes diarrhea
what gives someone immunity to the rotavirus?
a specific IgA in the gut lumen
or
IgA and IgG antibodies in the colostrum
what is the most common cause of severe diarrhea in children?
rotavirus
it’s the most common cause of severe diarrhea among children, with hospitalization of ~55,000 children/year in USA and the death of 600,000 children annually worldwide
what is the incubation period of the rotavirus?
about 2 days
what is the progression of the rotavirus?
incubation for 2 days
then vomiting and watery diarrhea for 3 - 8 days
fever and abdominal pain occur frequently too
immunity after infection is incomplete, but repeat infections tend to be less severe than the original infection