Especially in Latin America, a granulomatous mass (known as an amoeboma) may form in the wall of the ascending colon or rectum due to long-lasting immunological cellular response, and is sometimes confused with cancer.The ingestion of one viable cyst may cause an infection.Steroid therapy can occasionally provoke severe amoebic colitis in people with any E. histolytica infection. This bears high mortality: on average more than 50% with severe colitis die. Cause
Amoebiasis is an infection caused by the amoeba Entamoeba histolytica. Transmission
Amoebiasis is usually transmitted by the fecal-oral route, but it can also be transmitted indirectly through contact with dirty hands or objects as well as by anal-oral contact. Infection is spread through ingestion of the cyst form of the parasite, a semi-dormant and hardy structure found in feces. Any non-encysted amoebae, or trophozoites, die quickly after leaving the body but may also be present in stool: these are rarely the source of new infections. Since amoebiasis is transmitted through contaminated food and water, it is often endemic in regions of the world with limited modern sanitation systems, including México, Central America, western South America, South Asia, and western and southern Africa.Amoebic dysentery is one form of travelers diarrhea, although most travelers diarrhea is bacterial or viral in origin. Pathogenesis
Amoebiasis results from tissue destruction induced by the E. histolytica parasite. E. histolytica causes tissue damage by three main events: direct host cell killing, inflammation, and parasite invasion.
Since antibodies may persist for years after clinical cure, a positive serological result may not necessarily indicate an active infection. A negative serological result, however, can be equally important in excluding suspected tissue invasion by E. histolytica.Stool antigen detection tests have helped to overcome some of the limitations of stool microscopy. Antigen detection tests are easy to use, but they have variable sensitivity and specificity, especially in low-endemic areas.Polymerase chain reaction (PCR) is considered the gold standard for diagnosis but remains underutilized. Prevention
To help prevent the spread of amoebiasis around the home :
Wash hands thoroughly with soap and hot running water for at least 10 seconds after using the toilet or changing a babys diaper, and before handling food. Clean bathrooms and toilets often; pay particular attention to toilet seats and taps. Avoid sharing towels or face washers.To help prevent infection:
Avoid raw vegetables when in endemic areas, as they may have been fertilized using human feces. Boil water or treat with iodine tablets. Avoid eating street foods especially in public places where others are sharing sauces in one containerGood sanitary practice, as well as responsible sewage disposal or treatment, are necessary for the prevention of E. histolytica infection on an endemic level. E.histolytica cysts are usually resistant to chlorination, therefore sedimentation and filtration of water supplies are necessary to reduce the incidence of infection.E. histolytica cysts may be recovered from contaminated food by methods similar to those used for recovering Giardia lamblia cysts from feces.