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

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

An epidemiological study on Metagonimus yokogawai infection was performed in Samcheok-gun, Kangwon province during the period from November 1983 to October 1984. Formalin-ether concentration technique and Stoll's dilution egg counting method were employed to figure out the prevalence and infection intensity of M. yokogawai infection. The results are summarized as follows: The prevalence of M. yokogawai infection was 13.3 percent among 1,172 examined ; 18.0 percent (114 out of 632) in male and 7.8 percent (42 out of 540) in female. The prevalence rates were different by stream; 15.5 percent in Ohsip-chon (stream), 11.8 percent in Maeup-chon and 1.6 percent in Gagok-chon. Along the basin of Oship-chon; 8.2 percent at the lower reaches in Samcheok-eup, 25.9 percent at the middle reaches in Miro-myon and 6.2 percent at the upper reaches in Dogeoe-eup, respectively. By age group, the highest rate (18.3-20.2 percent) was observed in 30-49 years of age (male : 24.1-28.7 percent, female 11.2-13.2 percent). By social strata, the positive rate was 15.0 percent (120 out of 799) in general inhabitants and 9.7 percent (36 out of 373) in school children. Intensity by EPG count in feces was 419 in average; the light infection (less than 400 EPG) was 70.4 percent, moderate infection (401-1,000 EPG) 19.4 percent and heavy infection (more than 1,001 EPG) 10.2 percent respectively. All the 67 sweetfish (length 10.3-18.5 cm) which were caught from Ohsip-stream were infected with metacercariae of M. yokogawai and the number of metacercariae detected were 382 per fish in average (323 in June and 382 in September). Experiences of intake of raw fresh-water fish [Plecoglossus altivelis and Leuciscus (Tribolodon) sp.] were present in 50.3 percent (354 out of 704) of the inhabitants along Ohsip-stream according to questionnaire study. The results of this survey indicated that the middle reaches of Ohsip-stream in Miro-myon, Samcheok-gun is the endemic region for M. yokogawai infection.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; epidemiology ; metagonimiasis ; human ; Plecoglossus altivelis ; Leuciscus sp.

This study was undertaken to elucidate the status of Metagonimus species infection and to demonstrate the first and the second intermediate hosts of the fluke at the several localities along the Gum river, Chungchung-nam Do, Korea from March 1979 to October 1980. The results are summarized as follows: Total 790 stool specimens of inhabitants from 6 localities along Gum river were examined by the combination of cellophane thick smear technique and formalin-ether concentration technique. The positive rate of intestinal helminths was 80.3 percent, and the egg positive rate of Metagonimus sp. was 21 percent from a total of 790 specimens examined. In the age bracket of 20-49, the positive rates of Metagonimus sp. were 31.1-36.5 percent, and the males (26.8 percent) were infected three times higher than females (8.9 percent). By the area of the river, Gumsan which is located upper stream showed the highest positive rate (40.5 percent) of the fluke, whereas the rates decreased gradually toward upper part of river (Muju) or the descending lower area of the river. The most lower area of river (Gangkyeong and Nonsan), no positive Metagonimus infection case was found. The infection rate of Clonorchis sinensis in 790 was 37.3 percent, and the status of mixed infection of Metagonimus with C. sinensis was found 127 cases (76 percent) out of 166 cases with Metagonimus infection. The result of measurement of ova from 166 cases of Metagonimus infection, large ova were found in 41.1 percent, small size ova in 31.9 percent and the mixed type in 27.1 percent, respectively. The adult worms were recovered from the 6 cases after treatment with niclosamide, and the measurements of the worms showed similar morphological characteristics of the Metagonimus yokogawai. Twenty-two species in 5 families of fresh water fish were caught. Out of 22 species of fish, 18 species were found infected with metacercaria of Metagonimus. In order to observe the distribution of metacercariae in the body and the rate of infection of the individual host, a total of 94 Pseudogobio esocinus were examined. Total 84 (89.4 percent) out of 94 fish were infected with the metacercariae and the rates of distribution of the metacercaria were observed in the following order: on scale; 93.4 percent, in gill; 3.2 percent, head part; 2.9 percent, but a few metacercaria was found in muscle and visceral organs. The development of the metacercariae which were isolated from the scale of Pseudogobio esocinus were experimentally traced in the albino rat host from one day to 30 days after infection. At the 6th day, several eggs were visible in the uterine tubule of the some worms, on the 10th day, worms became 326.0 x 208.0 micrometer in size, however the bodies of worms grew no more until the 30th day after infection. The oral sucker was larger in size than the ventral sucker during early stage of the worms, but the 7th day after infection, it reversed. The ventral sucker situated on the ventral right side of the body. Right side of testis laid somewhat toward, and uterus and vetellaria extended to the posterior margin of the right testis. Snails(Koreanomelania nodifila var. ovulum) were collected in the river, Buri-Myeon, Gumsan-Gun, and found the natural emerging ophthalmo-pleurophocercus cercaria. From the above result, the prevalence of Metagonimus species infection showed relatively higher rates from the inhabitants along the middle to upper localities of the river. Even though no sweetfish was caught in the surveyed areas, Gum river basin is the one of the new endemic foci of metagonimiasis in Korea.
parasitology-helminth-trematoda ; Metagonimus spp. ; metagonimiasis-epidemiology ; taxonomy ; Ascaris lumbricoides ; Trichuris trichiura ; hookworm ; Trichostrongylus orientalis ; Clonorchis sinensis ; Taenia sp. ; Pseudogobio esocinus ; Acheilognathus intermedia ; Carassius carassius ; Hemibarbus labeo ; Hemibarbus longirostris ; Paracheilognathus rhombea ; Parapelecus jouyi ; Pseudopungtungia nigra ; Pungtungia herzi ; Sarcocheilichthys wakiyae ; Zacco playtpus ; Zacco temmincki ; Gobiobotia brevibarba ; Gobiobotia macrocephalus ; Siniperca kawamebari ; Siniperca scherzeri ; Liobagrus andersonii ; Pelteobargrus fluvidraco ; Pseudobagrus emarginatus ; Pseudobagrus sp. ; Mogurnda obscura ; Parasilurus asotus