L35 Diarrheal viruses Flashcards
Most enteric viruses are enveloped/non-enveloped, and thus are more susceptive/resistant to disinfection by alcohol.
non-enveloped;
resistant
All enteric viruses causes diarrhea. T/F. Why?
False
- they may disseminate via viremia > disease in other organs
e. g. Hepatitis A/E > acute hepatitis
e. g. Enterovirus: Hand Foot Mouth disease, meningitis, encephalitis
Other than viral causes, list other causes of acute gastroenteritis.
- Bacterial
- Salmonella, Shigella, Campylobacter - Parasites
- Giardia, Entamoeba histolytica - Drugs
- motility disturbances
- Irritable/inflammatory bowel disease (IBD)
DDx for foodborne diarrhea (not viral)? (7)
- Salmonella species
- Campylobacter species
- Shigella species
- Bacillus cereus
- Staphylococcus aureus
- Clostridium perfringens
- Escherichia coli O157 H7
DDx for viral diarrhea? (4)
- Rotavirus
- Norovirus (Human caliciviruses)
- Enteric adenovirus
- Astrovirus
DDx for parasitic diarrhea?
Immunosuppressed
- Cryptosporidium species
- Microsporidium species
Immunocompetent
- Giardia lamblia
- . Cryptosporidium species
- . Cyclospora
- . Entamoeba histolytica
DDx for traveler’s diarhhea?
Invasive + Secretory (8)
Invasive
- Shigella species
- Enteroinvasive E.coli
- E.coli O157:H7
- Enteropathogenic E.coli
- Salmonella species
- Campylobacter species
Secretory
- Vibrio cholera
- Enterotoxigenic E.coli
Rotavirus A. from Reoviridae B. non-enveloped C. dsDNA virus D. with 8 groups, Group A infect humans E. Minimal cross-species transmission
C is incorrect:
dsRNA virus
What is the most common causative virus to viral gastroenteritis in young children and neonates?
At what ages patients are symptomatic?
Rotavirus
- > 6 months and <5 years old + > 60 years old
- Asymptomatic <6 months because of maternal IgA; >5 years old because already infected, produced immunity
Rotavirus A. Male predominance B. Winter peak C. Via faecal-oral route D. Via respiratory route E. 1-2 days of the incubation period and causes diarrhea of 4-7 days
D is wrong
- should be Norovirus
- Rotavirus only faecal-oral route
What are the clinical presentations of Rotavirus infection?
Watery diarrhea
+/- vomitng, fever
> dehydration
Treatment for Rotavirus-caused gastroenteritis?
Rehydration (oral/IV)
Laboratory diagnosis for Rotavirus? (3)
Viral antigen detection
- Enzyme immunoassay
- Latex agglutination test
NOT
- PCR because the high load of viral shedding in stool, PCR is extremely sensitive
- EM because low throughput, technically demanding
Prevention of Rotavirus?
Oral vaccination (live attenuated vaccines)
- RotaRix: 2 doses, monovalent
- RotaTeq: 3 doses, pentavalent
- 1st dose between 6-14 weeks of age, last dose before 32 weeks
What are the contraindications of Rotavirus oral vaccine? (3)
- C/I in severe combined immunodeficiency (SCID)// immunocompromised
- Catch up vaccination not recommended: risk of intussusception
- Not co-administered with oral Polio vaccine: both contain live virus»_space;> increase GI motility > increase risk of intussusception
Norovirus A. Same family as sapovirus B. ssRNA C. non-enveloped D. is Winter vomiting disease E. MC source is from poultry
E is wrong, should be from seafood - contaminated/ inadequate cookng
D: Winter, somtimes summer too;
Epidemic!
A: yes, both from Caliciviridae
What is the MC cause of viral gastroenteritis in adults?
Norovirus
What are the routes of transmission of Norovirus?
- Fecal-oral route
- human-to-human (80%)
- Environment contamination
- Different outbreak patterns
- Respiratory route
- Inhalation of aerosols from feces/ vomitus
Norovirus has short incubation: 0.5-3 days
Duration: 1-4 days
Clinical presentations of Norovirus-caused gastroenteritis? (2)
Treatment?
- Projectile vomiting
- Diarrhea +/- fever
- rehydration as treatment
What is the laboratory diagnosis of Norovirus gastroenteritis?
RT-qPCR
- stool & rectal swabs (not vomitus)
NOT
- EM: technically demanding
- Viral Ag detection: not sensitive, for outbreak investigation only
Prevention of Norovirus?
NO vaccination available
- Hand hygiene - 1:99 bleach but not alcohol-based sanitizer (non-enveloped virus)
- Wash and cook food thoroughly
Enteric adenovirus
A. non-developed
B. dsDNA viruses
C. Types 40 and 41 are associated with GE
D. 2nd MC cause of GE in adults
E. Detected by Viral Ag detection by ELISA
D is incorrect
- should be 2nd MC of young children
Astrovirus
A. Small RNA virus
B. causes endemic GE in young children and adults
C. 10% of GE in children
D. Use of an antigen detection assay for laboratory diagnosis
E. Star-shaped surface morphology, 28nm in diameter
D is incorrect
- No good antigen detection assay
