Epidemiological and clinical studies on malayan filariasis in Cheju-do, Korea

의학과/박사A considerable amount of work has been done regarding the filarial worm in Korea, since Yoon(1927) found one male filaria from the left inguinal lymph gland by autopsy of one case with elephantiasis of both legs. although Yoon(1927) identified the parasite as Wuchereria bancrofti without any morphological study, it is the general opinion that Brugia malayi is generally recognized as the only species of human filaria in Korea. The malayan filaria is distributed predominantly in Cheju Island and its neighbouring islands, though several areas in the mainland also show endemicity.(Oh, 1929; Oh, 1930; Bun, 1939; Senoo, 1943; Hunter et al.. 1949; Paik, 1959; Lee et al., 1964; Hwang et al., 1965; Soh et al., 1966 and Seo et al., 1968 etc.). The present study was designed to elucidate the epidemiological and clinical features o B. malayi infection in Cheju Island. As the subjects, 981 students of Seogi Agricultural High School and Seogi Girl's High School(male, 257; female, 724) at Seogipo-Up(=town) were sampled in May, 1970. For the second step, samples were drawn among 521 students of Namwon Junior High School(male, 302; female, 219) and 164 school children(male, 97; female, 67) of Wimi Primary School located together at Namwon-Myun(=township), where high positive rates were calculated from the above survey at Seogipo-Up. Seven elephantiasis cases and six control inhabitants besides the students were also selected for some physiological investigation. The students gathered voluntarily at the period of 21:00∼23:00 hours. Three drops of blood from the examinees' finger tip were obtained by lancet to make the thick smear preparations on the clean, fat free slide glasses. The dried smears were brought to the laboratory, and microscopic examination of the dried blood smears were done after staining with Giemsa solution to detect the microfilariae. The environmental condition survey in the endemic areas was done with a questionnaire designed by the author. Fifty-three microfilariasis cases(male, 34; female, 19) and 47 control students(male 30; female, 17) of Namwon Junior High School were complied with this schedule. Physical measurement of body length by Martin's anthropometer(Super Co.), body weight by the portable weight balance, hand grip by Hand Grip Dynamometer(TKK), and back lift strength by Back Dynamometer(TKK) were examined with the ordinary methods. All the examinees took a good rest, seated 30 minutes before the test. After the number of heart beats and blood pressure of the examinees were checked by pulse meter(Heartpet HR-7A, Mitsubishi Electric Co.) and sphygomomanometer. The examinees exercised, practicing up and down the wooden box of 30cm height 5 minutes at the speed of 30 times in a minute. After the loading, the frequency of heart beat was measured by pulse meter with a minute interval. The increasing pulse and recovery rate of each test were calculated by the following formula: Increasing pulse=(Pulse immediately after H.S.T.)/(Resting pulse)×100 H.S.T.: Harvard Step-up Test Recovery rate=(Step for 5 mins(30×5')×300(30cm.))/(Total pulse at 1's+2's+3) All the examinees rested in the seat for 30 minutes before blood flow test. In the resting situation, a sphygmomanometer was fixed on the examinee's thigh to check the blood flow, and then Whitney's strain gauge for volume estimation of blood flow(ml/min/100gm tissue) was settled on the lower leg, respectively. All of the records were indicated on the dynograph(Beckman RS Type) by the perception of strain gauge plethysmograph. After measuring the arterial blood flow in succession of venous occlusion(50mmHg) at the resting period, arterial blood flow was occluded under 200mmHg pressure for 5 minutes. The first check of the arterial blood flow was performed immediately after reactive hyperemia(0' sec.), sustaining the venous occlusion. Five minutes after the first check, it was checked at 30 second intervals for 5 minutes and then continued at one minute interval for next 5 minutes. Up to 10th minute, the values detected in this test were calculated by the routine formula of blood flow test. For intelligence test standard questionnaire from which was published at the Institute of Educational Psychology, College of Education, Seoul National University was used. Serum protein was measured by rapid electrophoresis using sepraphore Ⅲ strip. Differential leukocyte count was done routinely Wright stain of thin blood smears. In the study of bacterial infection blood agar plate and thioglycollate broth media were used in culture for identification of bacteria. During the summer season(July-August) 1969, the insecticide tests for resistance on adults and larvae of Aedes togoi were carried out. Aedes togoi larvae were collected from the breeding places, tidewater rock pools in endemic area of filariasis in Cheju-Do, and adults in the test were bred in laboratory from the larvae. WHO standard method for insecticide resistance test on adults and larvae of mosquitoes(1963) was applied. The results were as follows: Eight out of 257 male students of Seogi Agricultural High School were microfilarial positives(3.1%). the students from Namwon-Myun, one of the high end endemic focus, revealed the highest prevalence(10.3%), and the positive cases among these students were the residents mostly in Wimi-Ri(Ri-village), Namwon-Ri and Taeheung-Ri located along the coastal area in Namwon-Myun. Out of 724 blood smears in Seogi Girl's High School, only 6(0.8%) were positive, and all of those were from Bupwhan-Ri, Hokeun-Ri in Seogipo-Up and Wimi-Ri in Namwon-Myun. Out of 521 students of Namwon Junior High School, the prevalence of the microfilariae was 10.9%(male, 12.3%; female, 9.1%). The positive rates were 10.2% in Taecheung-Ri, 26.8% in Wimi-Ri, 9.4% in Namwon-Ri and 8.2% in Shinheung-Ri, and all of them were located lining the coastal area; but none of the students who inhabited the mountainous are showed positive. The positive rate among 164 children in the fifth and sixth year grade of Wimi Primary School was 19.5%(male, 16.5%; female, 23.9%). The highest positive rate(22.8%) was found among the children resided at one out of 6 villages, Wimi-Ri, where the parasite has been highly prevalent. As a preliminary check to detect endemic foci of filariasis in a wide area the rusult of a night blood survey on children and students in school might be valuable for extensive practical field work on filariasis among general population. One hundred students of Namwon Junior High School(male, 64; female, 36) were subjected for the survey by questionnaire. In average, the family members of each household were 7.1 in the filariasis group(male, 30; female, 17) and 6.6 in the non-filariasis group(male, 30; female, 17). The numbers of the households in which the examinees dwelt more than 10 years in Cheju Island were 47(86.8%) in the filariasis group and 40(85.1%) in the non-filariasis group. Thirty-three households(62%) of the filariasis group were located within 500 meter area from the coastal line, and 15(31.9%) of the non-filariasis group. Elephantiasis patients were found in 18(33.9%) out of 53 households of filariasis students and in 8(17.0%) out of 47 households of the non-infected group. Fourteen out of 36 students(38.9%) misunderstood that elephantiasis was due to drink unsuitable water, and the students who gave the right answer about the vector of the filarial parasite were only 15%. Height and weight of the body, hand grip and back lift strength of the students aging 10 to 15 years were measured. The examinees were 80 students in both infected and non-infected group, respectively. Height and weight in 13 year-old and 15 year-old male students of the infected group showed a slight decrease as compared with the non-infected group, but no difference was observed in female groups. The mean values of the hand grip power between two groups were compared. The mean values of back lift strength in the filariasis students were 63.8kg in 10 year-old male group and 36.0kg in 11 year-old female group, whereas the values in healthy were 50.8kg and 44.2kg in the same age group. The hand grip and back lift strength tended to decrease significantly in the filariasis cases. Some physical examinations with special reference to Harvard Step-up Test were carried out in the 11 to 17 year-old students. the blood pressure(systolic and diastolic) and pulse were not different in the infected and non-infected students at the resting state. The pulse recovery rates after taking exercise by Harvard Step-up Test were 156.5(male) and 152.5(female) in the filariasis cases in contrast to 171.7(male) and 164.5(female) in non-filariasis group. In the same test, the values of increasing pulse were 176.8(male) and 179.6(female) in filariasis cases, but 169.2(male) and 161.8(female) in non-filariasis group. A 69 year-old female elephantiasis case who suffered from cuticular hypertrophy in right lower leg showed greater delayed recovery of arterial blood flow following reactive hyperemia in the elephantiasic leg than in the healthy side. In spite of taking time immediately after reactive hyperemia, the slope of blood flow curves on the dynograph was more precipitous in the swelling leg that in the control one. In comparison of blood flow following time in minutes among 7 elephantiasis cases and 6 control healthy, the increased of blood flow immediately after reactive hyperemia was more significant in healthy group(p-value