Amoebiasis, also known amoebic dysentery, is an infection caused by any of the amobae of the Entamoeba group. Symptoms are most common during infection by Entamoeba histolytica. Amoebiasis can be present with no, mild, or severe symptoms. Symptoms may include abdominal pain, diarrhea, or bloody diarrhea. Complications can include inflammation and ulceration of the colon with tissue death or perforation, which may result in peritonitis. People affected may develop anemia due to loss of blood.
Amoebic dysentery, amebiasis, entamoebiasis
The life-cycle of various intestinal Entamoeba species
Bloody diarrhea, abdominal pain
Severe colitis, colonic perforation, anemia
Amoebas of the Entamoeba group
Stool examination, antibodies in the blood
Tissue disease: metronidazole, tinidazole, nitazoxanide, dehydroemetine, chloroquine,
Intestinal infection: diloxanide furoate, iodoquinoline
Cysts of Entamoeba can survive for up to a month in soil or for up to 45 minutes under fingernails. Invasion of the intestinal lining results in bloody diarrhea. If the parasite reaches the bloodstream it can spread through the body, most frequently ending up in the liver where it can cause amoebic liver abscesses. Liver abscesses can occur without previous diarrhea. Diagnosis is typical by stool examination using a microscope, but may not reliably exclude infection or separate between specific types. An increased white blood cell count may be present in severe cases. The most accurate test is finding specific antibodies in the blood, but it may remain positive following treatment. Bacterial colitis can result in similar symptoms.
Prevention of amoebiasis is by improved sanitation, including separating food and water from faeces. 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. Effective treatment against all stages of the disease 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, though most cases occur in the developing world. About 480 million people are infected with amoebiasis and this results in the death of between 40,000–110,000 people a year. Most infections are now believed due to E. dispar. E. dispar is more common in certain areas and symptomatic cases may be less common 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 swallowing cysts of E. histolytica volunteers developed the disease.
Signs and symptoms
Most infected people, about 90%, are asymptomatic, but this disease has the potential to become serious. It is estimated that about 40,000 to 100,000 people worldwide die annually due to amoebiasis.
Infections can sometimes last for years if there is no treatment. Symptoms take from a few days to a few weeks to develop and manifest themselves, but usually it is about two to four weeks. Symptoms can range from mild diarrhea to dysentery with blood, coupled with intense abdominal pains. The blood comes from bleeding lesions created by the amoebae invading the lining of the colon. In about 10% of invasive cases the amoeba