Amoebic dysentery is caused by Entamoeba histolytica, which is most often acquired in the tropics.
The organism invades the colonic mucosa creating shallow ulcers with undermined edges.
- Reservoir - Humans are the only known reservoir
- Epidemiology - Infections occur worldwide but are endemic in countries with poor sanitation; most UK cases are imported by travellers to endemic areas
- Transmission - Main route is through ingestion of contaminated food or water. Person-to-person transmission may also occur between household and sexual contacts via faecal-oral route
- Incubation period - Usually 2-4 weeks but may last months to several years
- Clinical features - 90% of cases are asymptomatic
- diarrhoea with or without dysentery occurs in intestinal disease- symptoms are often few or mild, with loose stools, mucus and blood - however may lead to fulminating colitis
- complications of this condition include severe colitis, perforation, localised amoeboma and liver abscess.
- amoebic liver abscess may occur which can be fatal
- Period of infectiousness - cases are considered infectious as long as cysts continue to be excreted which may last several years
Note:
- confirmation via PCR is important to distinguish between E. histolytica and non-pathogenic strains e.g. E. dispar
Reference:
- PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections