Amoebiasis

Amoebiasis, or Amebiasis, refers to infection caused by the amoeba Entamoeba histolytica. The term Entamoebiasis is occasionally seen but is no longer in use; it refers to the same infection. Likewise amoebiasis is sometimes incorrectly used to refer to infection with other amoebae, but strictly speaking it should be reserved for Entamoeba histolytica infection. Other amoebae infecting humans include:

• Parasites
  • Dientamoeba fragilis, which causes Dientamoebiasis
  • Entamoeba dispar
  • Entamoeba hartmanni
  • Entamoeba coli
  • Entamoeba moshkovskii
  • Endolimax nana and
  • Iodamoeba butschlii.

Except for Dientamoeba, the parasites above are not thought to cause disease.

• Free living amoebas. These species are often described as "opportunistic free-living amoebas" as human infection is not an obligate part of their life cycle.
  • Naegleria fowleri, which causes Primary amoebic meningoencephalitis
  • Acanthamoeba, which causes Cutaneous amoebiasis and Acanthamoeba keratitis
  • Balamuthia mandrillaris, which causes Granulomatous amoebic encephalitis and Primary amoebic meningoencephalitis
  • Sappinia diploidea

A gastrointestinal infection that may or may not be symptomatic and can remain latent in an infected person for several years, amoebiasis is estimated to cause 70,000 deaths per year world wide. Symptoms can range from mild diarrhea to dysentery with blood and mucus in the stool. E. histolytica is usually a commensal organism. Severe amoebiasis infections (known as invasive or fulminant amoebiasis) occur in two major forms. Invasion of the intestinal lining causes amoebic dysentery or amoebic colitis. If the parasite reaches the bloodstream it can spread through the body, most frequently ending up in the liver where it causes amoebic liver abscesses. Liver abscesses can occur without previous development of amoebic dysentery. When no symptoms are present, the infected individual is still a carrier, able to spread the parasite to others through poor hygienic practices. While symptoms at onset can be similar to bacillary dysentery, amoebiasis is not bacteriological in origin and treatments differ, although both infections can be prevented by good sanitary practices.