What is "amoebiasis"

alt. (context medicine English) An infectious disease caused by the parasitic protozoan ''Entamoeba histolytica''; amoebic dysentery n. (context medicine English) An infectious disease caused by the parasitic protozoan ''Entamoeba histolytica''; amoebic dysentery

1. n. infection by a disease-causing ameba [syn: amebiasis, amebiosis, amoebiosis]

2. [also: amoebiases (pl)]

Amoebiasis, also known as amebiasis or entamoebiasis, is an infection caused by any of the amoebas of the Entamoeba group. Symptoms are most common upon infection by Entamoeba histolytica. Amoebiasis can present with no, mild, or severe symptoms. Symptoms may include abdominal pain, mild diarrhoea, bloody diarrhea or severe colitis with tissue death and perforation. This last complication may cause peritonitis. People affected may develop anemia due to loss of blood.

Invasion of the intestinal lining causes amoebic bloody diarrhea 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 diarrhea. Cysts of Entamoeba can survive for up to a month in soil or for up to 45 minutes under fingernails. It is important to differentiate between amoebiasis and bacterial colitis. The preferred diagnostic method is through faecal examination under microscope, but requires a skilled microscopist and may not be reliable when excluding infection. This method however may not be able to separate between specific types. Increased white blood cell count is present in severe cases, but not in mild ones. The most accurate test is for antibodies in the blood, but it may remain positive following treatment.

Prevention of amoebiasis is by separating food and water from faeces and by proper sanitation measures. There is no vaccine. There are two treatment options depending on the location of the infection. Amoebiasis in tissues is treated with either metronidazole, tinidazole, nitazoxanide, dehydroemetine or chloroquine, while luminal infection is treated with diloxanide furoate or iodoquinoline. For treatment to be effective against all stages of the amoeba may require a combination of medications. Infections without symptoms do not require treatment but infected individuals can spread the parasite to others and treatment can be considered. Treatment of other Entamoeba infections apart from E. histolytica is not needed.

Amoebiasis is present all over the world. About 480 million people are infected with what appears to be E. histolytica and these result in the death of between 40,000–110,000 people every year. Most infections are now ascribed to E. dispar. E. dispar is more common in certain areas and symptomatic cases may be fewer than previously reported. The first case of amoebiasis was documented in 1875 and in 1891 the disease was described in detail, resulting in the terms amoebic dysentery and amoebic liver abscess. Further evidence from the Philippines in 1913 found that upon ingesting cysts of E. histolytica volunteers developed the disease. It has been known since 1897 that at least one non-disease-causing species of Entamoeba existed (Entamoeba coli), but it was first formally recognized by the WHO in 1997 that E. histolytica was two species, despite this having first been proposed in 1925. In addition to the now-recognized E. dispar evidence shows there are at least two other species of Entamoeba that look the same in humans - E. moshkovskii and Entamoeba bangladeshi. The reason these species haven't been differentiated until recently is because of the reliance on appearance.