Mass control of ascariasis with single oral doses of levamisole. A controlled comparison in 3,056 subjects between three incomplete population coverages.

Ninety-, 60-, and 40-percent population coverages with levamisole 2.5 mg/kg of body weight were compared for their effects on Ascaris lumbricoides, ancylostoma, Strongyloides stercoralis, and Trichuris trichiura infections. They were shown to be effective in maintaining a reduced prevalence of A. lumbricoides in the treated subjects for 9, 6, and 3 months, respectively. Nine months after treatment, the prevalence of ascariasis was still lower than before treatment both in the levamisole and in the control subjects, regardless of the population coverage. This was probably because the egg output had been reduced. It is concluded that mass treatment with single oral doses of levamisole repeated at 3-month intervals might help control ascariasis, and that population coverages between 60 and 90% might be appropriate. No clear-cut effects against hookworms could be shown, possibly because the first follow-up examinations were performed three months after treatment. No changes in the prevalence of S. stercoralis and T. trichiura could be demonstrated. There were no adverse exp