Amoebiasis revisited

Abstract

Amoebiasis, a disease characterized by abdominal pain, loose motion, and blood-containing feces, is caused by a unicellular protozoan parasite Entamoeba histolytica. It afflicts nearly 500 million people worldwide and is the second leading cause of death from a parasitic infection in children under 5 years of age. The cysts are the infective stages, and the infection spreads through ingestion of mature cysts in fecally contaminated food and drinking water or by hands from an infected person. A majority of infected persons often remain asymptomatic; however, in some cases, infection can lead to severe clinical complications like dysentery and amoebic liver abscesses. Though metronidazole (a 5-nitroimidazole) continues to be a drug of choice for the treatment of amoebic dysentery, for its complete cure, a combination of a tissue amoebicide (usually a 5-nitroimidazole) and a luminal amoebicide (e.g., diloxanide furoate) is required. Unfortunately, the occurrence of E. histolytica strains resistant to metronidazole, its potential carcinogenicity, and a strong metallic taste after a few days of use are some of its big limitations. Satranidazole, a novel 5-nitroimidazole discovered and developed in India, is now available in several formulations. Nevertheless, the treatment of amoebiasis continues to remain far from satisfactory, and there is a strong and compelling need to discover and develop novel and improved antiamoebic drugs. Further, the availability of clean drinking water, proper sanitation, and good personal hygiene including handwashing will continue to remain important driving factors in tackling the problem of amoebiasis. This overview summarizes the history, life cycle, currently available drugs, and, more importantly, the progress on the discovery of novel antiamoebic agents and various preventive measures for the control of amoebiasis.