Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 1 1 1972 03 15 1 8 Arfaa F. Sahba G.H Farahmandian 2015 10 03 With the success achieved in the interruption of the transmission of bilharziasis by snail control in most endemic areas of Iran, mass-chemotherapy has been used extensively for reducing the number of cases in various villages. Niridazol was chosen for this purpose after a screening of several drugs. Eight thousand eight .l1undred seventy-four cases in 259 localities were treated from 1966 to the present time. The side-effects encountered were generally mild. This extensive mass-treatment has resulted in a reduction of the prevalence of infection below 10% in the majority of villages in all foci. The overall reduction in the positively rate was 92.2% in 100 villages where transmission had been stopped and 64.4% in 14 villages where transmission had not been stopped. The results of follow-up examinations revealed that only 3 and 2.1% of treated cases, respectively, were still passing viable eggs 3 and 6 months after therapy. The success achieved in this area, in spite of vast programs of irrigation development, is proof that with the schistosomicidal drugs now avails. https://ijph.tums.ac.ir/index.php/ijph/article/view/1509 https://ijph.tums.ac.ir/index.php/ijph/article/download/1509/1490