Because: (a) 80% of cases lost the carrier state during the follow-up, (b) no cases of disease in the placebo group were found, (c) there was an early acquisition of carrier state in the treatment group, (d) the difference in months free from carrier state between groups was small, and (e) because of the cost per month free of carrier state among treated persons, it was suggested that the treatment of asymptomatic carriers of E.histolytica/ E.dispar infection is not cost-effective. Resources should be redistributed to the treatment of amebic disease (mortality).