Abstract
Epidemiological analyses on the preventive effect of thiabendazole as an ovicide against human helminth infections are described. Thiabendazole was mixed in night-soil once a month during a period from April to October 1964 in the control of hookworm infection, and from June 1964 to March 1966 in the control of Ascaris and Trichuris infections. The findings are as follows: (1) The rate of new infections with hookworms (Necator americanus) in the treated area was two fold lower than that in the non-treated area. (2) The rate of new infections with Trichuris in the treated area was three fold lower than that in the non-treated area. (3) As to the new infections with Ascaris, the rate of patients with fertilized eggs in the treated area was four fold lower than that in the non-treated area. Moreover, new infections were found to occur in groups in the families of the non-treated area, whereas the incidence was sporadic in the treated area.