Viral Diarrhea Flashcards
What is the most common cause of severe diarrhea in YOUNG CHILDREN worldwide?
Rotavirus
What family is rotavirus in?
Reoviridae
What protein is the outer capsid of rotavirus?
VP7 (major outer capside protein) and VP4 (spike)
What protein is the inner capsid of rotavirus?
VP6
Is rotavirus genome segmented or unsegmented?
Segmented
Allows rearrangement and different strains
What is the function of VP7 and VP4?
Neutralization
Cleavage of VP7 by GI proteases initiates infection
VP4 also helps with binding
What is the function of VP6?
Basis of immunoassays
Determines Group A, B, or C
Which group of rotavirus is most common worldwide?
Group A
What is speculated to be the cause of diarrhea associated with rotavirus?
NSP4 enterotoxin
What is the most common serotype of rotavirus?
G1, P8
How is NSP4 thought to cause diarrhea?
Induces fluid secretion
Induces actin rearrangement and paracellular leakage
What is the mode of transmission of rotavirus?
Primarily: Fecal oral
Fomites
Common source (water or food)
Respiratory
What are the symptoms of rotavirus?
Vomiting
Watery diarrhea (no blood or fecal leukocytes)
Low grade fever
(All typical for most viral gastroenteritis)
What is the incubation period of rotavirus?
2 days
How was the rotavirus vaccine made?
Takes monkey rotavirus but has human rotavirus surface antigens
Causes immune response but no pathogenesis
Which serotypes of adenovirus that cause diarrhea?
Serotypes 40 and 41
What is the structure of the enteric adenovirus virion?
dsDNA
Penton fibre projects from each apex
What is the structure of astrovirus?
Small
ss (+) RNA
pointed star appearance
What are the two major caliciviruses?
Norovirus and sapovirus
What is the structure of rotavirus?
dsRNA
Wheel with spokes
What is the structure of caliciviruses?
non-enveloped
(+) RNA
Cup (calix) - shaped surface depressions
What is the most common viral agent of acute gastroenteritis outbreaks?
Norovirus
What is the mode of transmission of caliciviruses?
Fecal-oral
Food and water
aerosol
What is the seasonality of norovirus?
Winter peak
What blood type is at increased risk of calicivirus infection?
Group O bloodtype
Who is more susceptible to saporovirus and how do their symptoms manifest?
Young children
Diarrhea > vomiting
Who is more susceptible to norovirus and how do their symptoms manifest?
Older children and adults
Vomiting > diarrhea
How is rotavirus diagnosed?
Immunoassay for Group A rotavirus
How is enteric adenovirus diagnosed?
Assays detect serotypes 40/41
How is calicivirus diagnosed?
Electron microscopy
Serum antibody testing
RT-PCR
How is astrovirus diagnosed?
Electron microscopy
Serum antibody testing
RT-PCR
What is the treatment of viral diarrhea?
No antivirals Supportive care (fluid, electrolytes, food)
