Exam #5: Viral GI Tract Infections Flashcards
List the characteristics of the poliovirus.
Pirconaviridiae family
+ssRNA
Three serotypes (P1, P2, & P3)
*Stable in acidic pH
What allows polio to survive in the stomach?
Fact that it is stable at acidic pH
How is polio transmitted?
Fecal-oral
Note that the virus is shed in the stool for weeks following infection
What are the clinical manifestations of polio?
95% of infections asymptomatic
- Abortive poliomyelitis
- Nonparalytic aseptic meningitis
- Flaccid paralysis
What are the symptoms of abortive poliomyelitis?
Sore throat Fever Vomiting Abdominal pain Constipation
*Does NOT lead to paralysis
What are the symptoms of nonparalytic aseptic meningitis?
Nonspecific prodrome
Stiffness
What is the incidence of flaccid paralysis?
Less than 1% of infections
What are the two different forms of the polio vaccine?
Salk= inactivated polio vaccine (via exposure to formaldehyde)
Sabin= Oral, live, attenuated
*Note that this can be shed in the stool for up to six week following vaccination (and passed to other)
How is polio diagnosed?
Isolate virus from stool & sequence to differentiate between wild-type and vaccine
What is VAPP?
Vaccine Associated Paralytic Poliomyelitis
1/2 million doses of Sabin reverted to a neurotropic strain that caused CNS symptoms–>lead to paralytic polio symptoms & use was discontinued
What is viral gastroenteritis?
Inflammation of the stomach & intestines caused by a virus
What are the symptoms of viral gastroenteritis?
Nausea
Vomiting
Diarrhea
How is viral gastroenteritis transmitted?
Fecal-oral
What are the four viruses that cause viral gastroenteritis?
Rotavirus
Norovirus
Adenovirus
Astrovirus
*Note that all are non-enveloped
How does viral gastroenteritis differ from bacterial gastroenteritis?
- Incubation period for viral will NEVER be “hours” because replication must occur vs. bacterial gastroenteritis that can onset in hours (or min) because of preformed toxin
- Vomiting is more prominent in viral
- Diarrhea is non-bloody in viral gastroenteritis
- Viral is a “diagnosis of exclusion” aside from rotavirus & astrovirus
A common effect of viral gastroenteritis is dehydration. What are the symptoms of severe dehydration?
- Tachycardia
- Hypotension
- Skin tenting
- Sunken eyes
- Tears absent
- Lack of urination
*Possible a sunken fontanelle
List the characteristics of the Rotavirus.
DsRNA
Non-enveloped
Segmented
Describe the disease burden of Rotavirus.
- Responsible for 5-10% of all gastroenteritis among children less than 5 years-old
- Highest incidence among children 3 - 35 months of age
What happens to the Rotavirus morphology upon infection?
Rotavirus looks like a wheel due to the spoke-like appearance of its virion particles
*Note that “Rota” means wheel in Latin
Describe the clinical presentation of Rotavirus infection.
- 4-7 days of diarrhea, vomiting, & occasional cough
- Fever greater than 102F is seen in 1/3 of patients
What patient populations are at risk for life-threatening complications of Rotavirus infection?
Young
Malnourished
Immunodeficiency
Bone or liver transplant
What time of year is Rotavirus peak?
March
What is the most prevalent serotype of Rotavirus?
G1 G2 G9 G3 G4
Describe the pathogeneis of Rotavirus infection.
- Ingested virus infects the tip of the intestinal villi
- Infected cells are damaged & lost
- This villi blunting leads to malabsorptive diarrhea
*Regeneration of the villi within 4-7 days= end of symptoms
How is Rotavirus infection diagnosed?
EIA (enzyme-immunoassy) of stool sample
How is Rotavirus prevented? How is Rotavirus infection treated?
- Prevention of fecal-oral transmission
- IgA colostrums (first breast milk produced by the nursing other)
- Vaccine
What are the forms of the Rotavirus vaccine?
BOTH are live attenuated, oral vaccines
1) Rotateq
- Protective against G1 i.e. the reassortment of strains G4 & G9 (bovine & human reassortment)
2) Rotatrix
*Recommendation is vaccination prior to 12 weeks of age in all children & DOES NOT increase the risk of intussusception
What is intussusception?
Medical condition in which a part of the intestine invaginates (folds into) into another section of intestine, similar to the way the parts of a collapsible telescope slide into one another
List the characteristics of Norovirus.
Calicivirus family
Non-enveloped
+ssRNA
What is the disease burden of Norovirus?
Causes 96% of all outbreaks of nonbacterial gastroenteritis in the US (in all patient populations/ age groups)
Describe the pathogenesis of Norovirus.
Same as Rotavirus
What does Norovirus show a preference for?
Individuals expressing specific histo blood-group antigens; specifically, B antigen
*Note that this is only for one specific type of Norovirus (others infect other antigen groups)
What are the four ways that Norovirus can be transmitted?
Generally, fecal-oral:
1) Person to person
2) Fomites
3) Waterborne
4) Contaminated Food
List the characteristics of the Adenovirus.
DsDNA
Naked capsid
Fiber protein at vertices
Which serotypes of adenovirus cause gastroenteritis?
40 & 41
What patient population is most commonly affected by Adenovirus?
Children
How is adenovirus infection diagnosed?
Antibody detection in stool sample
What is the Sapovirus?
Calicivirideae family
i.e. similar to Norovirus
List the characteristics of Astrovirus.
Star-shaped
+ssRNA
Non-enveloped
Who is most susceptible to Astrovirus infection?
Infants
Young children
Elderly
