The efficacy of ivermectin in the chemotherapy of gastrointestinal helminthiasis in humans.

More than a billion individuals are infected with the four major soil-transmitted helminths of humans: Ascaris, hookworm, Trichuris, and Strongyloides [1]. In the developing world, available evidence suggests a substantial role for these intestinal nematodes in the generation of malnutrition and of the growth retardation that commonly follows [1]. Drug therapy for some of these intestinal helminth infections has existed for years, but polyparasitism is the rule in most affected individuals, and, unfortunately, no single broad spectrum anthelmintic agent has yet shown complete efficacy against all four nematodes [2]. Additionally, to be highly effective against Trichuris trichiura, Strongyloides stercoralis, or even hookworm, most drugs usually must be administered in multiple doses. A single anthelmintic drug effective in a single dose against all of these highly prevalent nematodes would clearly be advantageous. Ivermectin, an anthelmintic drug in wide use for several years by the veterinary industry, is unsurpassed both in its broad antinematode spectrum and in its remarkable potency when compared with previously available compounds [3]. In doses of up to 200 pg/kg this compound has recently been found to be safe and effective in humans [4]; larval forms of two systemic filarial nematodes of man, Onchocerca volvulus and Wuchereria bancrofti, are highly susceptible to therapy with ivermectin [5, 6]. As the drug has had extremely limited testing against gastrointestinal nematodes in humans [7], we conducted a pilot study to assess the efficacy of ivermectin as single-dose treatment against the common soil-transmitted helminthiases of humans.