Ecology of filariasis on Che Ju Island

, Kim, Joung Soon; , Lee, Won Young; , Chun, Suk Lak

doi:1973.11.1.33

Korean J Parasito > Volume 11(1):1973 > Article

Original Article


Korean J Parasitol. 1973 Apr;11(1):33-53. English. Published online Mar 20, 1994. http://dx.doi.org/10.3347/kjp.1973.11.1.33
Copyright © 1973 by The Korean Society for Parasitology


Ecology of filariasis on Che Ju Island
Joung Soon Kim,Won Young Lee and Suk Lak Chun
Department of Epidemiology, School of Public Health, Seoul National University, Korea.


Abstract
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.

Figures


	Fig. 1 Distribution of microfilaria counts in five persons by time when the blood was taken. (40mm³)


	Fig. 2 The location of area surveyed with Mf. rate of human filariasis.


	Fig. 3 Cumulative percent of microfilaria count/ 20mm³ of blood by village.


	Fig. 4 Microfilaria rate by age and sex.


	Fig. 5 Cumulative percent of microfilaria counts/ 20mm³ of blood by age group.


	Fig. 6 Percent of Mf Positives with more than 50Mf/ 20mm³ of blood by age group.


	Fig. 7 Ha Yae village map with the distribution of filariasis cases.


	Fig. 8 Tae Hung village map with the distribution of filariasis cases.


	Fig. 9 Bi Yang islet map with the distribution of filariasis cases.

Tables


	Table 1 Measurements of microfilariae by species and village


	Table 2 Experimental infection of animals with human filaria


	Table 3 Percent of population surveyed in all seven villages by sex summarized from three surveys


	Table 4 Percent of population surveyed by age and sex


	Table 5 Survey status by year and village


	Table 6 Microfilaria rate by village and sex (Summarized data for three years)


	Table 7 Percent of microfilaria positives with more than 50 Mf./ 20mm³ of blood by villages


	Table 8 Microfilaria rate by age and sex (Tae Hung, To San, Bi Yang, Hoengan), summarized data of all three surveys


	Table 9 Cumulative percent of microfilaria counts/ 20mm³ of blood by sex


	Table 10 Microfilaria rate by year and village


	Table 11 Percent of Mf negatives who became positive in one year by village, year, and Mf rate


	Table 12 Percent of microfilaria positives who became negative without treatment in the second or third survey by village


	Table 13 Change of microfilaria density in microfilaria positives without Hetrazan treatment


	Table 14 Clinical manifestation of filariasis A. Prevalence of clinical manifestation of filariasis by village


	Table 15 Prevalence of elephantiasis by village, sex, and age


	Table 16 Age of onset, duration of the illness, and frequency of occurrence by site for elephantiasis


	Table 17 Comparison of eosinophyl leucocyte count between microfilaria positive and negative


	Table 18 Animal survey for microfilaria species naturally infected


	Table 19 Percent distribution of adult mosquitoes by species collected in study areas (CDC Light Trap)


	Table 20 Natural mosquito infection status by filaria species compared with human infection

References


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