Study of Nitazoxanide in the Treatment of Amebiasis in Adults and Adolescents

Inclusion Criteria: * Age ≥12 years. * Patients with diarrhea (≥3 bowel movements/day) with one or more enteric symptoms such as bloody stools, rectal bleeding or enlarged colon. * Positive stool ELISA test for Entamoeba histolytica within 7 days prior to enrollment. Exclusion Criteria: * Patients with identified causes of diarrhea other than E. histolytica. * Use within 2 weeks of enrollment of any drug or therapy with possible anti-protozoal activity. * Females who are pregnant, suspected of being pregnant or breastfeeding. * Serious systemic disorders incompatible with the study. * History of hypersensitivity to nitazoxanide. * Patients in whom the possibility of receiving placebo and not being able to receive immediately an effective treatment will be incompatible with the severity of the patient's illness. * Patients with amebic liver abscess. * Patients known to have or suspected of having AIDS. * Patient with immune deficiencies.