Viral GI infections Flashcards
What clues point to viral gastroenteritis? (4)
No bacterial warning signs such as fever, bloody diarrhea, severe abdominal cramping. Vomiting is prominent. Incubation period is longer than a toxigenic disease. Entire illness is over in less than 72 hours.
What are the 5 viruses associated with GI infections?
Rotavirus, calicivirus, enteric adenovirus, astrovirus, hepatitis A and E
What is the most common viral cause of acute viral gastroenteritis in adults?
Norovirus, (+)ssRNA, non-enveloped
Describe the epidemiology, clinical presentation and transmission of norovirus
Highly infectious, short incubation, short illness
Projectile vomiting, explosive diarrhea
Can be transmitted by fecal/oral route, contact/fomites and aerosols
Which genogroups of norovirus generally cause disease in humans?
Mostly in G2 and G4
When detecting and characterizing norovirus, which regions of its genome would you use for each?
For detecting: use a region that is more likely to mutate so that you can determine the strain that is causing the illness.
For characterizing: use a region of the genome that is less likely to mutate
What makes rotavirus hardy in nature?
It has three capsids
How is rotavirus spread and detected?
Spread by oral-fecal or food/waterborne. It is detected by RT-PCR or antigens
What are the clinical features of rotavirus? (2)
Low-grade fever and vomiting for 2-4 days. Frequent explosive non-bloody diarrhea.
What is the most common cause of viral gastroenteritis in children? What is the second most common cause?
Rotavirus, followed by enteric adenoviruses
What is the morphology of enteric adenoviruses? Which types cause gastroenteritis?
Linear dsDNA virus, non-enveloped, types 40 and 41 cause gastroenteritis
How are enteric adenoviruses different from noro/rotaviruses? (3)
Longer incubation period, less severe symptoms such as fever and dehydration, longer period of illness
What is morphology of astrovirus? (2)
Non-enveloped, (+)ssRNA
List the differences between water-borne and blood-borne hepatitis viruses in terms of types, morphology, and whether the infection is acute or chronic
Water-borne: HAV and HEV, (+)ssRNA, non-enveloped, no chronic infection
Blood-borne: HBV, HCV, HDV. Enveloped. May cause chronic disease
What hepatitis viruses are RNA viruses and which are DNA?
A, C, E are RNA viruses
B and D are DNA viruses
What are 3 clinical features of HAV?
Incubation is 2-6 weeks, usually self limiting with no chronic disease, risk of symptoms increases with age
What are the symptoms of HAV and how long do they typically last for?
Fatigue, nausea, vomitting, abdominal pain
Jaundice
Dark amber urine (bilirubin excreted in urine)
How is infection of HAV usually detected?
By serology of blood.
In regard to serology of HAV, which type of antibody represents an acute infection and a chronic infection?
IgM indicates an acute infection
IgG indicates chronic infection or immunity
Describe 3 methods used for the diagnosis of viral gastroenteritis?
Antigen detection: moderate sensitivity (60%), used for rota, noro and adenovirus
Molecular testing: much more sensitive, conventional or RT-PCR
Serology: used for HAV and HEV only
