This study investigate the epidemiological feature of Metagonimus infection in Kangwon-do (province). The average infection rate of the surveyed inhabitants was 7.8% (83 positives out of 1, 067 examinees) by stool examination; male, 11.4% and female, 3.2%, respectively. The egg positive rate in residents in the Som river area was 7.3%, that of the Chuchon river area 6.3%, the Pyongchang river area 12.8%, the Tong river area 3.8%, the Hongchon river area 9.8%, and the Ohsip stream area of Samchok 8.0%, respectively. The average metacercarial infection rate of genus Metagonimus in the fish was 81.0% (256 positives out of 318 fish). The infected fishes were Zacco platypus, Zacco temmincki, Opsariichthys bidens, Squalidis sp., Carassius carassius, etc. in western Kangwon-do Meanwhile, in the Ohsip stream area of Samchok-gun, eastern costal Kangwon-do, the infected fish were Plecoglossus altivelis and Tribolodon hakonensis. The rats and dogs are infected with the metcercariae obtained from Zacco platypus and Opsariichthys bidens, adult worms collected were Miyata type of Metagonimus with some M. takahashii. When infected with metacercariae from Plecoglossus altivelis, Metagonimus yokogawai was only found. M. yokogawai and Metagonimus Miyata type were found together in Tribolodon hakonensis in Ohsip stream area of Samchok, in the eastern Kangwon-do. The intestinal flukes of genus Metagonimus in western Kangwon-do were Miyata type of Metagonimus and M. takahashii, transmitting mainly by Zacco platypus and Opsariichthys bidens as a source of infection. In the eastern part of Kangwon province (Ohsip stream area of Samchok), M. yokogawai was mainly distributed by P. altivelis and T. hakonesis, but some T. hakonensis harbored the metacercariae of Miyata type of Metagonimus with those of M. yokogawai.

The Hongcheon river system flows down through the Hongcheon area of Kangwon-do, and reaches to the Cheongpyeong Dam in Kyonggi-do. Stool specimens from the inhabitants residing along the Hongcheon river basin were examined to detect infection rate of Metagonimus sp., and the intermediate hosts were collected to detect larval stages. The results obtained were as follows: Thirty-nine (33 males and 6 females) out of 529 (314 males and 215 females) inhabitants were infected with Metagonimus sp., showing a total positive rate of 7.4 per cent. In eight areas surveyed, the specimens from Kulji-ri of Bukbang-myon at the middle part of the river showed the highest positive rate of 26.9 per cent (14 positives out of 52) (males; 38.2 per cent). The specimens from Mogog-ri of Seo-myon at the downstream of the river showed a positive rate of 10.4 per cent (13 positives out of 125) (males;12.6 per cent). The positive rates in other regions were less than 10 per cent. The density of the first intermediate host, Semisulcospira sp., was the highest in Kulji-ri of Bukbang-myon (10-20 snails per m(2)), and the infection rate of Metagonimus cercariae in the snails was 10.7 per cent(13 positives out of 121 snails). The infection rate of Metagonimus metacercariae in Zacco platypus, the fresh water fish favorably eaten raw by the inhabitants, was 68.2 per cent (30 positives out of 44 fishes), and most metacercariae were detected under the scales (89.9 per cent). Adult flukes were obtained from the small intestine of a rat, 15 days after infection with the metacercariae obtained from Z. platypus. These adult flukes were identified to be the same srecies as those obtained from human hosts. By this survey, new endemic areas of Metagonimus infection were discovered along the Hongcheon river basin and the main source of infection was the fresh water fish, Z. platypus.

An epidemiological study and mass treatments of Enterobius vermicularis infection among children near Wonju area of Kangwon province were carried out. The children were divided into 4 groups according to their residing localities; children in the mountainous area, rural area, urban area and in orphanage. They were examined by adhesive cellotape anal swab technique, and egg positive rates were obtained. The rates of egg reduction and re-infection rates after repeated mass treatments were also observed. The results obtained were as follows: 1. The overall egg positive rate of E. vermicularis in the first screening was 19.9% (251 out of 1,262 examinees; 19.7% in males and 20.1% in females). The positive rates were 13.0% in the mountainous area, 11.9% in the rural area, 15.1% in the urban (medium-sized) area and 61.9% in orphanages. 2. The highest positive rates were observed in the kindergarten children, and 1st and 2nd grade children of primary schools (26.2-32.2%), and the lowest rate (13.6%) in 6-year grade children of primary schools. 3. Cumulative detection rates from 3 repeated anal swabs at 4-5 days interval were higher (70.8%) than those from single anal swabs (50.0-59.2%). 4. Out of the examinees who showed the highest cumulative positive rate (70.8%), about 39.2% were consecutively positive in 3 anal swabs. Among different groups of children, the higher the total egg detection rates (87.5%), the higher the consecutive positive rates (71.9%). 5. A total of 2,609 (male: female = 1:12.4) worms were collected from 17 egg-positive cases treated with anthelmintics. The mean number of worms per child was 153 (range: 4-824).(ABSTRACT TRUNCATED AT 250 WORDS)

Five cases infected with Rhabditis sp. were detected in a survey to examine the stool specimen from rural primary school children. A large number of the larvae of Rhabditis sp. detected by the direct cellophane thick smear were cultured by the filter paper method. The examination was carried out in April through June 1980 in Tangjeong-Myon, Ahsan-Gun, and in September 1983 in Sandong-Eup, Yeongwol-Gun. The results obtained in this study were as follows: Prevalence: Out of 925 children, 5(0.54%) children were found to be positive. The number of the detected larvae was 110/0.1 gm of feces in case 1, 35 in case 2, 130 in case 3, 86 in case 4 and 62 in case 5. Larvae: The larvae were prepared by means of the direct fecal smear and measured by a micrometer equipped in the microscope. Twelve(12) through 15-day old larvae in culture were 197.1 micrometer long in average, and the maximum size of the matured stage larvae was 884.0 x 25.9 micrometer. However, the length variation was ranged as 173.0 to 884.0 micrometer. Adults: The size of clubbed adult female was 1,357 micrometer(1,176~1,419) in length and 80 micrometer(79~82) in width. Length of buccal cavity was 33 micrometer. A long cylindrical esophagus (273 micrometer) of the worms with a valved posterior cardiac bulb and with median bulbar swelling was morphologically indicated. Distance from mouth to vulva was occupied 58 percent of body length. Male worm was 1,006 micrometer (890~1,148) in length and 49 micrometer(48~49) wide. Caudal alae of bursa and spicules (75 micrometer in length) were well developed. Eggs: The oval shaped eggs in the female uterus, when cultured, were 66 x 56 micrometer in size, and the eggs laid by the adult could not be detected. So, reproduction might be through to be ovoviviparity. The five cases were re-examined during the period from the 1st to the 3rd week after stool examinations, but Rhabditis sp. were detected again in 4 cases in 1st week. When they were examined in 3rd week, larvae could not be detected. So, it was thought that the infection of Rhabditis sp. to humans was facultative.

The Philippines has been known as an endemic area for malaria (Belizario et al., 1997), schistosomiasis japonicum (Mcgarvey et al., 1996) and intestinal capillariasis (Cross, 1992). The Philippines and Southeast Asia are reported as highly prevalent areas of intestinal helminthes as well (Carney et al., 1981; Chai and Hongvanthong, 1998). The Philippines are divided into 3 large provinces, Luzon, Visayas, and Mindanao. Legaspi city is located in Visayas area, 544 km from Manila (Fig. 1). To evaluate the status of intestinal parasites infection among children and adolescents in the Philippines, we visited Legaspi city, Philippines, in December, 1998. With the aid of a local missionary, fecal examination was performed on 64 cases of children and adolescents by formalin-ether concentration method. The age of the examinees ranged from 3 to 20 years old, and they were divided into two groups, rural and urban areas. The most of the rural examinees were farmers. The mean infection rate of 64 examinee was 78.1% for helminths and protozoa. The infection rate of intestinal parasites in primary school children was 95.5% which was higher than the rates in preschool children or adolescents. The infection rate in rural area was 92.3% higher than that of urban area (56%). Trichuris trichiura (51%), Ascaris lumbricoides (40%) and hookworm (23.4%), were found to be highly prevalent intestinal helminthes in this study.