28. Epidemiology and prevention of enteric viral infections
Viral enteric infections
- Rotavirus
- Norovirus
- Poliovirus
Rotavirus
- Epidemiology
- The leading cause of severe diarrhoeal disease in infants and children worldwide
- Most common cause of diarrhoeal deaths in developing countries
- Most common during the winter in temperate climates
- Year-round in tropical climates
- Virtually all children in developing countries are infected before they reach age 3
- RV can also infect adults
- Especially institutionalized and hospitalized
- Transmission
- Spreads rapidly among nonimmune children
- Faecal-oral
- Respiratory droplets
- Contaminated objects
- Symptoms
- Watery diarrhoea
- Vomiting
- Abdominal pain
- Vaccine
- Live attenuated oral vaccine
- Childhood vaccine
- At week 6 and month 3
Norovirus
- A calicivirus
- Epidemiology
- Most common cause of winter gastroenteritis (stomach flu)
- Most common cause of adult gastroenteritis
- Common in developed and developing countries
- Outbreaks common in
- Nursing homes
- Hospitals
- Cruise ships
- Transmission
- Faecal-oral
- Person-to-person
- Virus can survive freezing and heating to 60 degrees
- Virus can shed in asymptomatic people for 2 weeks
- Clinical features
- Self-limiting
- Diarrhoea
- Vomiting
- Abdominal cramp
- Diarrhoea
- Fever
- No vaccine
Poliovirus
- Epidemiology
- Mainly affects children under 5
- In pre-vaccine era virtually all children had polio in their life
- Transmission
- Humans are the only known reservoir
- Faecal-oral
- Clinical features
- 95% develop very mild, flu-like symptoms
- 4% may develop aseptic meningitis, myalgia
- 1% develop paralytic poliomyelitis
- Treatment
- Mild cases are self-limiting
- No cure for severe form
- Surveillance for acute flaccid paralysis
- = the gold standard for detecting poliomyelitis
- Prevention
- Vaccine
- Clean water
- Hygiene
- Oral polio vaccine (Sabin)
- Used in countries with high incidence of polio, or neighbours with high incidence of polio
- Live attenuated
- Gives long-lasting immunity
- Gives immunity at the mucous membranes of the intestines
- The attenuated virus can be excreted in faeces and immunize other people
- Has a small risk of vaccine-associated paralytic polio
- Inactivated polio vaccine (Salk)
- Used in most countries
- Killed virus
- Given by IM injection
- No risk of vaccine-associated paralytic polio
- More expensive