This survey was undertaken to determine the recent prevalence of lung fluke, Paragonimus westermani, in the three localities of Wiseong county, Kyungpook Province, Korea and to compare the prevalence among the residents in the same areas between 1924 and 1980. The three localities, Ku-seong, Sam-chun, and Um-ji villages (dong) have been known as the endemic areas of Paragonimus westermani. The surveys were made on the general population. They were examined using intradermal test with Paragonimus westermani antigen, and the diagnosis of paragonimiasis was made depending on the positive intradermal reaction. The sputum examination could not be performed beacause the residents were inaccessible. The prevalence of Paragonimus westermani among the residents in the three communities varied from 1.4 percent to 7.9 per cent, with an average of 4.0 per cent. Whereas, the average reported by Ichinomiya in 1924 was 4.7 percent. There are no significant differences in the sex and age specific rates of infection between 1924 and 1980. With the abundant density of Semisulcospira snails and crayfish in Sam-chun stream and the high rate of infection with Paragonimus westermani among the residents in the village, it is found that Sam-chun village, one of the three localitied in Wiseong county, where Ichinomiya (1924) surveyed, was still the endemic focus of Paragonimus westermani.
parasitology-helminth-trematoda ; Paragonimus westermani ; paragonimiasis ; epidemiology

In order to determine the epidemiological patten of the liver fluke, Clonorchis sinensis, the locality where the snail, Parafossarulus manchouricus, is abundant, the infestation rates for the cercarial and metacercarial larvae of digenetic trematodes in the snail and fish hosts, and the prevalence of Clonorchis sinensis among the residents in the vicinity of river Taewha, Kyungnam Province, Korea were studied from March 1979 to September 1980. Four snail habitats were found in the river Taewha. The population density of the snail per square meter of the habits ranged from 10 to 500, with an average of 150. Among the 4 snail habitats, three, Baek-cheon, Sa-yeon and Taewha had snails infected with the cercaria of Clonorchis sinensis, and the proportion of infested snails in the three habitats was very low, the average being 0.59 per thousand. Four species of fresh-water fish, the bullhead, Coreobagrus brevicorpus, the Korean shiner, Gnathopogon atromaculatus, the flat bitterling, Paracheilognathus rhombea, and the striped shiner, Pungtungia herzi among ten species of fish examined harbored the metacercaria of Clonorchis sinensis. The intensity of infestation with the cyst of Clonorchis sinensis in the four species of fish was low. The approximate number of the cysts per gram of flesh was between 3.5 in Paracheilognathus rhombea and 21.5 in Gnathopogon atromaculatus. Seven kinds of laval tremathodes, Clonorchis sinensis, Cyathocotyle orientalis, Echinochasmus species, Exorchis oviformis, Metacercaria hasegawai, Metagonimus yokogawai and Metorchis orientalis were found from ten species of fish examined. In general, the infestation rates for the encysted larvae of digenetic trematodes varied from fish to fish. The infection rate for Clonorchis sinensis among the residents in the vicinity of river Taewha was relatively high, 22.2 percent by the formalin-ether sedimentation technique, and the difference in the rate of infection between males and females found to be siginificant(t>2). Of these, the rate was 12.4 per cent in 483 elementary school children and 17.7 percent in 761 middle and high school students. The results obtained in the present study indicate that endemic foci of Clonorchis sinensis exist in the river Taewha and the prevalence of the liver fluke among the residents is still high.
parasitology-helminth-trematoda ; Clonorchis sinensis ; epidemiology

Metacercariae were found from 6 samples among 4,382 Parlemon nipponensis which were caught at Podu, Kohung, Korea. The metacercaria was inclined as a larval stage of Paragonimus westermani by following reason: Semisulcospira libertina was the only one species which lives in Podu area. No other metacercaria except Paragonimus westermani were found from the craw or cray fish which were caught in the endemic aera. Metacercariae, ovary, testes and cuticular spines resmbled the characteristics of Paragonimus westermani, which have been described by previous workers.
parasitology ; helminth ; trematoda ; Paragonimus westermani ; metacercaria ; epidemiology

Prevalence study of Metagonimus yokogawai infection, survey of intermediate hosts of Metagonimus yokogawai and food habits of raw sweetfish among inhabitants along Boseong river (120 km), Jeonra Nam Do (province) were carried out. The results are summarized as follows: Among 360 examined, the egg positive case were 128(35.6 percent); male 112(46.7 percent), female 16(13.3 percent). The prevalence rates were different by geographical areas; 42.4 percent in down stream, 49.4 percent in middle stream and 13.3 percent in upper stream. By ages, highest rate, 53.6-59.1 percent was observed among 30-49 group (male 69.6-73.0 percent, female 15.8-35.5 percent). Eggs per gram of feces were 2,084 (200-12,280) in average; down stream 1,708, middle stream 2,590, upper stream l,550. By social strata, the prevalence showed differences; 24.8 percent in primary schoolchildren, 78.4 percent in school teacher and local officers, 30.6 percent in general inhabitants. Clonorchis sinensis infected cases in the areas were 21(5.8 percent) out of 360 examined, and 90.5 percent of them showed mixed infection with Metagonimus yokogawai. Cercariae of Metagonimus yokogawai from the lst intermediate host, Semisulcospira sp., in down and middle streams were detected from 32 snails (5.9 percent) out of 545 examined. All the 22 Plecoglossus altivelis which were caught from the down stream were infected with metacercariae of Metagonimus yokogawai. The number of the metacercariae detected was 22,650 per fish in average, and the number increased from August to October. Experiences of raw sweetfish intake of the inhabitants were found in 208(58.4%) among 356 interviewed by questionaire form (male 76.7 percent, female 20.7 percent). Means of acquisition of the sweetfish were mostly by purchase 68.8 percent, and seasonally in summer. Reason of the raw sweetfish intake was due to the flavor, 83.2 percent. The fish were mixed in soy sause with vinegar before the intake.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; metagonimiasis ; epidemiology

This study was undertaken to evaluate the effects of health education and anti-Clonorchis campaign conducted in Kyungpook Province and to compare the prevalence of Clonorchis sinensis among the residents in the same areas for the period 1964-1976. Both surveys were made on all age groups of residents ranging from 0 to over 60 years of age. They were examined using primarily intradermal tests with Clonorchis and Paragonimus antigens and followed by stool examinations. The definitive diagnosis of clonorchiasis was made on the recovery of Clonorchis eggs from the stools. A marked reduction in the prevalence was encountered in the youngest age group, but there is no significant difference in the older age groups. The overall prevalence rate for clonorchiasis was reduced from 27.7 to 19.6 per cent in a period of 10 years. It is found that clonorchiasis is less prevalent in Kyungpook Province than it was a decade ago and it continued to decline.
parasitology-helminth-trematoda ; Clonorchis sinensis-clonorchiasis ; Paragonimus westermani ; epidemiology

Nishimura in 1943 indicated for the first time that a serious endemic focus of Clonorchis sinensis is located in the vicinity of Yeong-cheon(Kyungpook Province, Korea). Later, numerous surveys of this fluke in the Province have been made, but no additional report on the endemic focus of the fluke has been available. The overall percentage of Clonorchis sinensis infections, based on the discovery of eggs by the formalin-ether sedimentation technique, was found to be 54.8 percent from 851 residents in Nakjeon ri (village), Danmil myun, Uiseong gun (county), Kyungpook Province and no significant difference was observed in the sex specific rate of the individuals infected. There is a high incidence of infection with Clonorchis sinensis. The infection rate in the age group from 0 to 4 years was 14.6 per cent, 5 to 9 years was 35.7 per cent and 10 to 14 years was 51.7 per cent. In the worn burdens for residents, the average number of egg-counts was 41,800. It is found that a serious endemic focus of Clonorchis sinensis exists in the vicinity of Nakjeon village.
parasitology-helminth-trematoda-Clonorchis sinensis ; epidemiology ; formalin-ether

A study was carried out to figure the cases and to observe the endemic status of clonorchiasis and metagonimiasis in endemic areas in Korea. Total 13,373 inhabitants living in 40 villages along 7 main rivers and 9 small streams were subjected to stool examination. They were selected randomly among the riverside population. Their specimens were examined both by cellphane thick smear method and Stoll's egg countung technique. This study was performed during the period from May 1979 to April 1980. The results obtained are as follows: The egg positive rate of any kind of helminths was 58.7% out of 13,373 examned cases, and the egg positive rates by each helminth were; Clonorchis sinensis 21.5%, Metagonimus yokogaqai 4.8%, large type Metagonimus eggs 0.4%, Ascaris lumbricoides 22.9%, Trichuris trichiura 35.2%, hookworm 0.2%, Taenia sp. 0.5%, Hymenolepis nana 0.07%, Paragonimus westermani 2 cases, Fasciola sp. 4 cases, Echinostoma sp. 1 case and Hymenolepis diminuta 1 case respectively. Many endemic foci of clonorchiasis were revealed along the 7 major rivers. The egg positive rates of each river basin differed from each other significantly; Nagdonggang 40.2%, Yeongsangang 30.8%, Seomjingang 17.3%, Hangang 15.7%, Tamjingang 15.9%, Geumgang 12.0% and Mangyeonggang 8.0%. The cases of clonorchiasis were estimated in range 830,000 to 890,000 in riverside areas of the 7 rivers. By grading the infection intensity, 64.7% was in Grade I(EPG 0-900), 28.6% in Grade II (EPG 1000-9,900), 5.5% in Grade III (EPG 10,000-29,900) and 1.3% in Grade IV (EPG over 30,000). The proportion of the cases in Grade III and IV was 6.8% among positive cases. Therefore 60,000 cases at least were regarded to suffer from it clinically. Males of 30-60 years of age showed higher positive rate and heavier burden of infection. This makes clonorchiasis more important socially because the patients lose their social productivity. A few endemic foci of metagonimiasis were detected newly by egg detection; Samcheong 28.5% egg positive rate, Uljin 21.3%, Yeuongdeog 46.3%, Milyang 6.7%, Yeongil 9.2% and Geoje 18.2%. The mean EPG values were in range of 320-7, 120 by the focus. The egg positive rate and proportion of EPG Grade varied greatly by the area, and mean proportion of the positive cases were 69.7% in Grade I, 24.1% in Grade II, 5.0% in Grade III and 1.2% in Grade IV. Males of 30-60 years were infected in higher rate also. The large sized eggs of Metagonimus were found also in upper basin of Hangang and Geumgang mainly. They were regarded as eggs of M. takahashii which is mediated by the cyprinid fishes. Its significance should be studied further. Clonorchiasis and metagonimiasis should be realized as important public health problems in Korea by their wide distribution, high prevalence rate and heavy infection intensity. Comprehensive measures against them are needed urgently.
parasitology-helminth-trematoda ; clonorchiasis ; metagonimiasis ; Clonorchisis sinensis ; Metagonimus yokogawai ; epidemiology

To understand the mode of transmission in clonorchiasis, a survey was made in Kim-hae Goon, South Kyong-sang Do (=Province). The mathematical analysis of the age prevalence was done on the egg positive rates. And another analysis for the comparison was also made to the cited data from two areas, North Kyong-sang Do and Ko-yang Goon, Kyong-gi Do. Some catalytic models of H. Muench (1959) were applied to the observed age prevalence. Because the both parameters, such as force of infection(a) and loss of positivity(b) were considered to be constant for a long period in the surveyed area, the two stage catalytic model by Muench was chosen to the analysis. In the surveyed area, Kim-hae Goon where the egg positive rates were 56.2 percent and 61.2 percent (by Kim, 1974), the constant values of 'a' were found to be 0.051 and 0.089 respectively. In other words, the force of infection was 51, 89 per 1,000 susceptibles. The values of 'b' were found to be 0.006 and 0.005. This means that the rates of disappearance from egg positive cases to negative were 6 and 5 per annum per l,000 positive cases in above area. Therefore, the two catalytic curves were expressed by the following equations, y = 1.133 {e(-0.006t) - e(-0.051t)} and y = 1.047 {e(-0.005t) - e(-0.089t)} respectively. In the cases of North Kyong-sang Do and Ko-yang Goon, Kyong-gi Do where the egg positive rates of clonorchis shown as 27.7 percent and 15.2 percent by Shin (1964) and Kim (l974), the curves were expressed by y = 1.769 {e(-0.010t) - e(-0.034t)} and y = 2.857 {e(-0.020t) - e(-0.027t)} respectively. From the above mathematical analyses by age prevalence in clonorchiasis, it was considered that the mode of transmission of clonorchiasis in the surveyed area, Kim-hae Goon presented more rapid pattern than those of North Kyong-sang Do and Ko-yang Goon, Kyong-gi Do.
parasitology-helminth-trematoda ; clonorchiasis-Clnorchis sinensis ; epidemiology ; transmission

An epidemiological survey on Metagonimus yokogawai infection was performed in the eastern coast area of Kangwon province. Formalin-ether concentration technique and Stoll's dilution egg counting method were employed to figure out the prevalence and intensity of M. yokogawai infection and eating habits of inhabitants with raw freshwater fish. The results are summarized as follows: The prevalence rate of M. yokogawai infection was 6.6% among a total of 2,357 examinees; 8.6% (115 out of 1,345) in male and 4.0% (40 out of 1,012) in female. The prevalence rates were different by the streams where the examinees were residing: 17.8% along the area of Ohsip-cheon (stream), 11.8% along Maeup-cheon, 1.7% along Hwasang-cheon, 1.3% along Yeongok-cheon, 0.9% along Namdae-cheon, 0.9% along Sa-cheon and 0% in the other streams (Yongchon-cheon, Kangnung Namdae-cheon and Jusoo-cheon) in decreasing order. By social strata, the positive rate was 8.0% (122 out of 1,521) in general inhabitants and 3.9% (33 out of 836) in school children. By the intensity of infection by means of EPG counts in feces; the light infection (less than 400/EPG) was 74.1%, moderate infection (401-1,000/EPG) 17.3% and heavy infection (more than 1,001/EPG) 8.6%. Twelves out of 50 sweetfish (Plecoglossus altivelis) (24%) caught from the streams in eastern coast of Kangwon-Do were infected with metacercariae of M. yokogawai, and the number of larvae detected were 70.7 per fish in average. The metacercarial infection rate in fish were also different by the streams; 100% in Ohsip-cheon of Samcheok-Gun, 14.3% in Sa-cheon, 16.7% in Yeongok-cheon of Myeongju-Gun and 0% in Namdae-cheon of Yangyang-Gun, respectively. Six hundred ninety five (695) out of 1,396 inhabitants and school children (49.8%) were experienced in eating raw freshwater fishes (Plecoglossus altivelis, Tribolodon hakonensis, Coreoperca sp., Moroco sp., Carassius sp. & Cyprinus sp. and Zacco platypus). The data were assayed with the questionnaire collected from the examinees. In summarizing the above results, it is known that the Ohsip-cheon area of Samcheok-Gun is highly infected region, and the other areas of Kangnung Namdae-cheon, Yeongok-cheon and Yangyang Namdae-cheon are very lowly infected or non-infected regions for M. yokogawai infection.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; epidemiology ; Plecoglossus altivelis

The infection rates with cercaria and metacercaria of the Clonorchis sinensis in snail and fish hosts, and the prevalence among the inhabitants in the lower Nag Dong river in Busan were investigated in the period from June 1981 to March 1982. The stool examination and E.P.G. count for prevalence and intensity of clonorchiasis were done by cellophane thick smear and Stoll's egg count methods. The prevalence rate of clonorchiasis among inhabitants of 3 towns in Bug Gu, was 38.4% among a total of 1,384 persons examined. By town, the prevalence in Gu Po was 25.4% out of 330 persons examined, 39.3% in 438 examined in Gang Dong and 44.8% out of 616 in examined in Myeng Ji respectively. According to sex, the male(41.9%) showed relatively higher rate than female(35.3%). By age, increase of rate was observed as increase in age. The highest rate was 80.7% in 50-59 years group. The intensity of infection was light: 89.1% of examined cases were below 10,000 E.P.G. ; by area 80.9%(Gu Po), 80.2%(Gang Dong), 97.3%(Myeng JI). Out of fresh water fish species collected, 2 species were not infected with metacercaria. The metacercarial detection rate from fish in low Nag Dong river showed 100% in Pseudorasbora parva, Pseudogobio esocinus(41.4%), Hemibarbus labeo(37.1%), Acheilognathus limbata(33.3%) and Erythroculter erthropterus(4.5%) respectively. The mean number of metacercaria per gram of muscle was 21.2 in P. parva, P. esocinus(15.0), H. labeo(11.9), A. limbata(6.3), and E. erythropterus(1.6) respectively. Though 7 area along Nag Dong river were surveyed for Parafossarulus manchouricus, the snails were not found at all areas except for one area, Seo Nam stream; and the cercaria was infected 0.9% out of 708 examined.
parasitology-helminth-trematoda ; Clonorchis sinensis ; clonorchiasis-epidemiology ; host