Epidemiology of Infectious Diseases: Amoebic Dysentery
Causal agent
Infection with the protozoan parasite Entamoeba histolytica.
Common clinical features
Most infections are asymptomatic.
Intestinal disease ranges from acute or fulminating dysentery with fever, chills and bloody or mucoid diarrhoea to mild abdominal discomfort with diarrhoea containing blood or mucus, alternating with periods of constipation or remission1.
Epidemiology
- Endemic worldwide.
- A higher incidence is found in developing countries.
Reservoir
Humans
Mode of transmission
Faecal oral route.
Ingestion of faecally contaminated food or water containing amoebic cysts1.
Incubation period
Range of a few days to several months or years. Commonly 2-4 weeks.
Period of Communicability
While E. histolytica cysts are excreted (may continue for years).
Laboratory Confirmation
Diagnosis is by microscopic demonstration of trophozoites or cysts in fresh stool samples.
Three specimens are required to exclude amoebiasis2.
Prevention and control
Advice to overseas travellers on food hygiene and water treatment.
References
1.Heymann D L, editor, Control of Communicable Disease Manual. 18th ed. American Public Health Association; 2004.
2.Hawker J, Begg N, Blair I, Reintjes R, Weinberg J. Communicable Disease Control Handbook, Blackwell, 2005
© CM Kirwan 2006