Virology

1. Diarrheal Viruses

2. Viral Gastroenteritis
 Viruses probably cause upto 3/4 of all infective
diarrheas.
 The second most common viral illness after upper
respiratory tract infection.
 In developing countries, a major killer of
undernourished infants.
 Rotaviruses cause of half a million deaths per year.
 Only some gut-asociated viruses cause
gastroenteritis.

3. Gastroenteritis Viruses
• Rotaviruses
• Adenoviruses
•Astroviruses
• Calciviruses

4. Rotavirus Particle

5. Rotaviruses
 Naked ds RNA viruses, 80 nm in diameter.
 50-80% of all cases of viral gastroenteritis.
 Severe symptoms in neonates and young children.
 Up to 30% mortality rate in malnourished children,
responsible for up to half a million deaths per year.
 Symptomatic infections again common in people
over 60.

6. Rotavirus Pathogenesis

7. Rotaviruses
 Faecal-oral spread
 Incubation period 24-48 hr
 Abrupt onset of vomiting and diarrhoea,
a low grade fever may be present
 Live attenuated vaccines now available
for use in children

8. Rotaviruses Replication

9. Global Distribution of
Rotavirus Gastroenteritis

10. Diagnosis of Rotavirus Infection
 Rapid antigen testing of the stool, either by
ELISA (>98% sensitivity and specificity)
 Anti-rotavirus antibodies (IgM and IgA) are
excreted in the stool after the first day of
illness
 Antibodies remain positive for 10 days after
primary infection and longer after re-infection
 80% of the population have antibody against
rotavirus by the age of 3
 Electron microscopy

11. Enteric Adenoviruses
 Naked DNA viruses, 75 nm in diameter.
 Types 40 and 41are associated with gastroenteritis.
 Possibly the second most common viral cause of
gastroenteritis (7-15% of all endemic cases).
 Most people have antibodies against enteric
adenoviruses by the age of 3.
 Diagnosed by electron microscopy or by the
detection of adenovirus antigens in faeces by
ELISA