RESUMO
Study of filariasis to determine important factors involved in its ecology was carried out on Che Ju Island for three consecutive years from 1968 to 1970 in seven villages, three coastal villages and four islets remote from the main island. One village which was located in mountainous area far from the coast was surveyed to serve as control area. About 90% of population inhabiting the study area had at least one blood smear during the three-year period; about one third had three blood smears, and a little over one third had two, and the rest only one examination. Animal and mosquito surveys were carried out at the same period. Followings are the results obtained: 1. All human cases but several had microfilariae identical to the description of B. malayi. The several cases who had morphologically different microfilariae from that of B. malayi need further study for definite conclusion. 2. Five persons randomly sampled from Mf positives and bled every two hours demonstrated nocturnal periodicity between 9 p.m. and 3 a.m. 3. Human is considered to be only reservoir host for human filariasis in the area since animal survey and experimental exposure to the infective larvae of human filaria species showed failure to infect animals. 4. Microfilaria rate, microfilaria density, prevalence of elephantiasis varied by area and age with correlation, which indicated cumulative process of the parasite by repeated exposure and development of host immunity to certain extent. 5. Clinical manifestation of filariasis (symptom complex and elephantiasis ) taken from history and inspection was low in its prevalence with range of 0.9% 11.8% of total population. Only 5.2% of 517 Mf positives had the clinical manifestation. 24.8% of 109 persons with clinical manifestation had microfilaria; 42.9% with symptom complex only, 23.1% with both symptoms and elephantiasis, and none with elephantiasis only were microfilaria positive. 6. Ae. togoi was the only species infected with the filaria. Mosquito infection rate by area showed positive correlation to the Mf rate and density of human population; where the Mf rate and density were high, the mosquito infection rate also high.
RESUMO
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: 1. 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. 2. 6 mg of hetrazan/kg B.W. X12 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. 3. 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. 4. Mosquito infection rates were also dropped markedly in areas where mf positive were mass treated. 5. Side reaction induced by diethylcarbamazine was frequent(64%-90%) and various. The most frequent symptom was headache and fever. 6. DDT spray did not influence human mf rate and mosquito infection rate.
