A 36 year old male patient from Gatsata, Nyabugogo,  has consulted our outpatient department for abdominal pain that has persisted for over two weeks; he has developed frequent bowel movements or diarrhea two days before coming to the hospital. He reports to have developed a bloody stool few hours before entering the consultation room. He reports no history of food intoxication.At the hospital, the doctor advised to take stool from him for laboratory investigation. The doctor on duty also carried out sigmoidoscopy to examine the colon for the characteristic ulcerations and to rule out other possible causes of the symptoms.The sigmoidoscopy exam turned out to be normal. However, laboratory results showed the presence of trophozoites of amebiasis in his stool. Trophozoite is an infesting stage of the amebiasis parasite.He was prescribed entamizole 500mg tablets to use three times a day for seven days. Entamizole is a derivative of the flagyl or metronidazole generic drug. It is useful in the treatment of amebiasis infestations as well as other gastro-intestinal tract infections.Today the man has no abdominal cramps or pain but has been warned on several hygienic issues to consider in order to prevent amebiasis re-infestation. The Parasite responsible or amebiasis infestation is Entamoeba histolytica, a single-cell organism that enters the body by drinking contaminated water or eating contaminated food with E. histolytica in cyst form.The cyst is a protective encasing within which the ameba may sustain itself in a dormant stage for weeks to months outside a host (an organism that provides nutrients for a parasite).Once within the small intestine the cyst ruptures and the ameba emerges to enter its active stage. In this active stage the ameba called a trophozoite, travels to the large intestine where it feeds on intestinal bacteria.As the number of trophozoites increases, they burrow into the intestinal mucosa (mucous lining of the colon). Substances trophozoites secrete to digest the substances they consume, cause ulcerations or sores that produce symptoms.Occasionally trophozoites penetrate far enough into the intestinal mucosa to enter the blood circulation, which transports them to other organs and extends the infection.The liver is the most common site for distant infection, where it presents as a hepatic abscess though the lungs and brain may also become involved. In locations other than the colon the trophozoites can cause abscesses, resulting in serious life-threatening illness.Symptoms of systemic infection depend on the affected area. Amebiasis is most common in countries where community sanitation is poor.Many people suffer episodes of amebiasis attack if exposed to unhygienic conditions. The infection spreads through direct contact with fecal contamination, eating vegetables from contaminated soil or drinking contaminated water.People who have amebiasis can spread the infection to other people. Diligent hand washing and safe food preparation are effective measures for preventing the spread of amebiasis.Visitors to countries where sanitation is substandard should follow precautions that include eating only foods that are thoroughly cooked and drinking only bottled or canned beverages or water boiled for a minimum of one minute.Treatment for enteric or systemic infection is a combination of antibiotic medications. Appropriate treatment cures the infection. Inadequately treated or untreated amebiasis becomes chronic with cycles of alternating recurrence and remission of symptoms.Until recently doctors believed it was possible to have an E. histolytica infestation without symptoms.Mr Kamugisha is a doctor at the Rwanda Military Hospital, Kanombe.