Evaluation of the effect of different methods of control of soil-transmitted helminths in Khuzestan, southwest Iran.

Three methods of control of soil-transmitted helminths, namely, sanitation, mass-treatment, and sanitation plus mass-treatment, were tried in 15 villages in Khuzestan, southwest Iran. Stool samples from the inhabitants of each village were examined both quantitatively and qualitatively just before starting each control method and again about 4 years later, except for the inhabitants of one village whose stools were re-examined 7 months after moving to a new settlement. Sanitation measures consisted of one latrine for each family and the provision of a sanitary water supply in each village. The drugs piperazine and bephenium hydroxynapthoate were administered alternately every 3 months. The reduction in rates of infection with Ascaris, hookworm, and Trichostrongylus spp., respectively, for the above mentioned methods were as follows: sanitation alone, 28%, 4% and 30%; mass-treatment alone, 84%, 73%, and 31%; sanitation plus mass-treatment, 79%, 69%, and 30% and in the newly constructed village, 76%, 21%, and 38%. In a control group corresponding reductions were 19%, 11%, and 31%. The percentage of egg reduction in persons still infected with these three parasites was, respectively, as follows: mass-treatment plus sanitation, 88%, 88%, and 53%; mass-treatment alone, 90%, 87%, and 37%; sanitation alone, 60%, 26%, and 0.6%; in the newly constructed village, 87%, 78%, and 39%; and in the control group, 29% increased 12%, and 24.5%. The significance of these findings is discussed.