This study was carried out for three years from 1968 to 1970. Three coastal villages and four remote islets of Che Ju Island were surveyed and 90% of all inhabitants were blood smeared. These study areas were grouped into five according to its characteristic for evaluation of mass treatment with diethylcarbamazine citrate (Hetrazan U.S.P.) and insecticide spray in control of human filariasis. To set baseline up for control group, placebo was administered. Followings are the results obtained: 81.1% of all mf positives accepted and completed the mass chemotherapy; main reason for refusal was side reactions told by neighboring villagers who experienced them. 6 mg of hetrazan/kg B.W. x 12 doses given every day turned mf postives to mf negative in 92.1%. The patients who had high mf density remained mf positive in 16.5% whereas only 2.1% for low mf density. 73.8% of mf positives after the treatment showed marked decrease in mf density. Most of them to less than 15n mg/20 mm(3) of blood that can not infect mosquito effectively. Mosquito infection rates were also dropped markedly in areas where mf positive were mass treated. Side reaction induced by diethylcarbamazine was frequent(64%-90%) and various. The most frequent symptom was headache and fever. DDT spray did not influence human mf rate and mosquito infection rate.
