Treatment options for the eradication of intestinal protozoa

Pathogenic intestinal protozoa are responsible for clinically important infections in both the developed and developing world. Treatments have been available for several decades for giardiasis, isosporiasis and amoebiasis, but until recently there were no effective remedies for the intestinal coccidia—cyptosporidium, microsporidium and cyclospora. In this Review, the author discusses the various pathogenic intestinal protozoa and the treatment options available. Pathogenic intestinal protozoa are responsible for clinically important infections in both the developed and the developing world. These organisms are responsible for both acute and chronic diarrhea, and Entamoeba histolytica , which affects the colon, can spread to involve the liver. Many of these pathogens, particularly the intracellular protozoa that predominantly affect the small intestine, produce their most devastating effects in patients with HIV/AIDS and other forms of immune deficiency. There are also various intestinal protozoa that do not seem to have any adverse effects on humans and can, therefore, be regarded as harmless commensal organisms. Although treatment has been available for several decades for giardiasis, isosporiasis and amoebiasis, until recently there have been no effective remedies for infection with intestinal coccidia— Cryptosporidium , Microsporidium and Cyclospora species. Cyclospora respond well to co-trimoxazole, microsporidia respond variably to albendazole, and cryptosporidia can often be eradicated by nitazoxanide. In chronically infected HIV-positive patients, treatment with multidrug regimens usually results in rapid resolution of the diarrhea and, in many instances, eradication of the parasite. Key Points Intestinal protozoa cause clinically significant infections in both the developed and developing worlds, particularly in individuals with impaired cell-mediated immunity The clinical impact of infection with intracellular intestinal protozoa ( Cryptosporidium , Microsporidia , Cyclospora , Isospora ) in HIV-positive patients has been dramatically reduced following the introduction of highly active antiretroviral therapy (i.e. triple drug regimens) Cryptosporidiosis was a major clinical challenge, but can now be effectively treated with nitazoxanide (a substituted benzamide); treatment with nitazoxanide is also effective and safe in children Infection with the relatively new pathogen Cyclospora (like Isospora infection) can be cleared with co-trimoxazole Micro