An epidemiological study was performed to know the infection status of E. hortense among the human residents and fish intermediate hosts in Chongsong-gun, Kyongsangbuk-do. Out of 263 people examined, 59(22.4 per cent) were positive for the eggs of E. hortense. Total 152 fresh water tishes (9 species) were examined, and Odontobutis obscura interrupta, Misgurnus angullicaudatus and Squalidus coreanus were found to harbour the metacercariae of E. hortense. Juvenile or adult E. hortense were expelled from 35 out of 54 cases treated with praziquantel. The number of worms per individual ranged from l to 649, with the average burden of 51. The eosinophil count of infected persons ranged 1-24 per cent (6 per cent in average). The number of eggs per day per worm (EPDPW) in human host was estimated about 1,478. The results showed that Chongsong-gun is an endemic area of E. hortense.
parasitology-helminth-tematoda ; Echinostoma hortense ; Hippeutis cantori ; epidemiology

Two cases of human Echinostoma hortense infection were found in Seoul Paik Hospital. Their stools revealed echinostomatid eggs. After treatment with praziquantel (single does of 10-12 mg/kg) and purgation with magnesium salt, total 21 flukes were collected in one case. The flukes were 5.9-7.5 mm long, had 27-28 collar spines around their head, laterally deviated ovary and two tandem testes. They were identified as E. hortense Asada, 1926. The cases are 38-year and 20-year old men residing in Seoul, whose hometown is Chungsong-gun and Seungju-gun, Kyongsangbuk-do respectively. They had eaten raw flesh of various kinds of fresh water fishes (both cases) and/or salamander (latter case), which are considered possible sources of this fluke infection. They experienced abdominal discomfort and/or diarrhea. Hematology revealed 22 percent eosinophilia in the latter case, but it became 5 percent after the treatment. Echinostomatid eggs were not found after the treatment in both cases. These are the 4th and 5th human cases of E. hortense infection in Korea.
parasitology-helminth-trematoda ; Echinostoma hortense ; case report ; praziquantel ; intestine

The tegumental ultrastructures of Echinostoma hortense adults were observed by scanning electron microscopy. The worms of 4 weeks of age were harvested from albino rats experimentally infected with the metacercariae obtained from the loach. The results were as follows: The worms were leaf-like and their anterior end portion, including oral sucker and head crown, ventrally curved to face posteriorly. The tegument of whole body was wrinkled transversely and covered with cobblestone-like cytoplasmic processes. The oral sucker had roundly swollen (type II) sensory papillae on the ventral half of its lip and uni-ciliated knob-like (type I) sensory papillae, arranged in 2-3 rows, on the dorsal outer surface. Aspinous ventral sucker had many of type I papillae arranged in a circular band on its outer surface. The tegument around the genital opening was of similar feature to the ventral sucker, but sensory papillae were hardly found around the former. Scale-like spines with broad base and round tip were distributed densely on the tegument anterior to the ventral sucker but they became sparse in posterior half of the ventral surface, finally to disappear at posterior extremity. A few number of type I papillae were observed on the ventral surface. The results suggest that the tegument of E. hortense is similar to that of other echinostomes especially E. revolutum. But the number and arrangement of collar spines, and/or the type and distribution of sensory papillae seem characteristic features of E. hortense differed from other echinostomes.
parasitology-helminth-trematoda ; Echinostoma hortense ; electron microscopy

Total of 2,643 Korean soldiers were examined of their stool for parasitic infections by both cellophane thick smear and formalin-ether concentration techniques from August 1983 to December 1985. Out of them, 73.6% were free from any parasite, 22.6% were ova positive and 4.0% cyst positive. The ova positive rates by species were Ascaris lumbricoides 2.0%, Trichuris trichiura 13.0%, hookworm and Trichostrongylus orientalis 0.08% respectively, Clonorchis sinensis 7.6%, Metagonimus yokogawai 1.1%, Paragonimus westermani 0.08%, Echinostoma hortense 0.04%, Fibricola seoulensis 0.9%, Taenia sp. 0.3%, Hymenolepis nana 0.2% and H. diminuta 0.04%. Most of them (87.3%) were positive by a species, 11.9% by two and 0.8% by 3 species. The cyst positive rates were Entamoeba histolytica 0.6%, E. coli 1.4%, Endolimax nana 1.7%, Iodoameba butschlii 0.04% and Giardia lambla 0.9%. Among the cyst positives, 89.5% were positive by a species, 7.6% by two and 0.5% by 3 species. The intestinal parasite infections among the Korean soldiers decreased distinctly compared with previous data.
parasitology-helminth-nematoda ; trematoda ; cestoda ; protozoa ; epidemiology ; Clonorchis sinensis ; Trichuris trichiura ; Metagonimus yokogawai ; hookworm ; Ascaris lumbricoides ; Diphyllobothrium latum ; Hymenolepis nana ; Entamoeba histolytica ; Giardia lamblia ; Entamoeba coli ; Endolimax nana ; Trichostrongylus orientalis ; Paragonimus westermani ; Echinostoma hortense ; Fibricola seoulensis ; Taenia sp. ; Hymenolepis diminuta

Recently there have been some reports on human infections of Echinostoma hortense in Korea. It was found that a few species of freshwater fishes were playing the role of the second intermediate host of E. hortense. However, molluscan intermediate host has not been identified yet in Korea. The present study aimed to establish the life cycle of E. hortense in laboratory. Experimental studies such as egg production from the rat, development of the eggs in vitro, exposure of miracidia to freshwater snails, shedding pattern of cercariae from infected snails, morphology of cercariae, cercarial infection to the second intermediate host and infection of metacercariae to the difinitive hosts were done. In addition, epidemiological surveys on the infection status in inhabitants and house rats, and on the natural infection of larval echinostomes in the snails and fishes were carried out along the South Hangang-river. The results obtained were as follows: The eggs deposited from adults in physiological saline were cultivated at room temperature (20-24C). The miracidia were firstly observed on 8 days after cultivation, and 85.5 per cent of the eggs contained the mature miracidia on 11 days after cultivation. More than 90 per cent formed the miracidia when cultivated at temperature 22-27C. Hatching of the miracidia began on 12 days after cultivation and continued for a week. The size of the miracidia was 103.0 x 51.4 micrometer in average. The motility of miracidia were active up to 8 hours after shedding, but they were all dead within 10 hours after shedding. A freshwater snail, Radix auricularia coreana was cultivated in aquaria. A hatched F1 snails from the egg masses were exposed to 20 miracidia respectively. Escape of cercariae started on 15 days after infection. Radix auricularia coreana was experimentally identified as the first intermediate host of E. hortense in Korea. Cercarial shedding started on 15-20 days after infection by snail, continued for about 10 days (8.8 days in average). Infected snails were dead within 32 days after the miracidial infection. About 1,335 cercariae (328-1,994) per snail were shed in its life, and 119 cercariae in average per snail per day were shed. The cercariae were motile for more than 24 hours, and then squirming at the bottom until death. The body and tail sizes of cercariae were 356 x 186 micrometer and 510 x 68 micrometer in average, respectively. The rediae parasitized in the snail hosts were found mainly around the pericardial regions, and their size was 1,575 x 258 micrometer in average. The numbers of developing cercariae in a mature redia were 14 in average (7-20 in range). The numbers of rediae in a snail were 102 in average on 15 days after miracidial infection and 221 in average on 28 days. Three uninfected Misgurnus anguillicaudatus, less than 6.5 cm long were used in for the cercaria1 infection. They were all exposed with 755 cercariae, and examined at 5-day intervals starting from 10 days after infection. All the fihes were infected with metacercariae of E. hortense and a total of 275 was found infected (36.4 per cent). The metacercariae were fed to rats and the adult worms were obtained on 15 days after infection. The infected rats began to deposit the eggs on 11 days after infection. The number of eggs deposited per day per worm (EPD/worm) was 400-500 on 3 weeks after infection and was increased to 1,000-1,500 on 4 to 17 weeks, then decreased to 800 on 2l weeks after infection. A total of 745 stool specimens collected from 576 male and 169 female residents of 8 different villages along South Hangang basin was examined. Out of 745 specimens, the eggs of Echinostoma sp. were found in 2 cases (0.3 per cent). Of 34 house rats one showed egg-positive (2.9 per cent). Total 971 Radix auricularia coreana collected from 7 sampling stations were examined for shedding of cercariae. Three snails (0.3 per cent) shed the cercariae of E. hortense. A total of 119 out of 542 freshwater fishes (22.0 per cent) had the metacercariae of E. hortense. The fishes parasitized with the metacercariae were 4 out of 14 examined species. The infection rate of 4 species were 34.1 per cent (106 out of 311) in Misgurnus anguillicaudatus, 30.4 per cent 7 out of 23) in Misgurnus mizolepis, 4.3 per cent (2 out of 46) in Moroco oxycephalus and 22.2 per cent (4 out of 18) in Odontobutis obscura interrupta. In summarizing the above results, the first intermediate host of E. hortense was found as Radix auricularia coreana in Korea. Also it took about 46 days for the shortest completion of a life cycle of E. hortense in summer; that is, 10 days for miracidial development in eggs, 15 days for cercarial development in the snail, about 10 days for metacercarial development in the second intermediate hosts, 11 days for the maturation as the adults in the definitive hosts. The natural infection rates of E. hortense in the intermediate hosts were relatively high but those in the definitive hosts were low in the middle areas of South Hangang basin.
parasitology-helminth-trematoda ; Echinostoma hortense ; epidemiology ; biology ; Misgurnus anguillicaudatus ; Misgurnus mizolepis ; Moroco oxycephalus ; Odontobutis obscura interrupta ; Radix auricularia

The metacercariae of an echinostomatid fluke were detected from a freshwater fish, Odontobutis obscura interrupta caught from the Seom river system, Wonseong-gun, Kangwon-do, and experimenally infected into rats to obtain the adult worms for the species identification. A total of 32 metacercariae was detected from 10 fishes (27.8 percent) out of 36 O. obscura interrupta caught from the river. The average size of metacercariae was 153.4 x 149.0 micrometer. Also, it was uniquely specific that thickened membrane was formed around the metacercarial cyst wall. The rats orally infected with those metacercariae were sacrificed 20 days after infection to get the adult worms. The mean length and width of the adult worms were 0.75 cm and 0.13 cm, respectively. The number of collar spines on circumoral disk was 26 to 28, and the end group spines at lateral sides of the oral sucker were 4 on each side. The echinostomatid flukes observed in this study were all identified as Echinostoma hortense according to the morphologies of the cirrus sac, ovary, vitellaria and testes of the adult worms and the shape of eggs. On the other hand, O. obscura interrupta is one of the fresh-water fish that are preferably eaten raw by the rural inhabitants. Although no human case of E. hortense infection by eating O. obscura interrupta has been experienced yet, the possibility is strongly suggested in this study.
parasitology-helminth-trematoda ; Echinostoma hortense ; metacercariae ; Odontobutis obscura interrupta ; rat

Two cases of human Echinostoma hortense infection and their probable infection source were identified by praziqantel (Distocide) treatment of the patients and by examining two kinds of fresh water fish which were eaten raw by them. The result of the research can be summarized as follows: The patients, each aged 31 and 30, were residing in the same house in Wonju City, Kangwon Province. The first case was hospitalized due to epidemic hemorrhagic fever (E.H. fever) and the second case was healthy but had slight degree of abdominal pain and diarrhea from time to time. In the stool examination, eggs of E. hortense (114.3 x 71.0 micrometer average from the first case and 119.1 x 68.3 micrometer average from the second) were found. By administering single dose of praziquantel (10~15 mg/kg) and purgation with magnesium salt to them, six adults of E. hortense were collected from the diarrheal stools of the second case. By examining 84 Moroco oxycephalus and 20 Carassius carassius which were captured at the place where the two patients had captured and eaten the fresh water fish, the metacercariae of Echinostoma sp. were found from 3 (3.5 percent) M. oxycephalus. After the experimental infection of 3 isolated metacercariae to one albino rat three adults of E. hortense were recovered. By the present study, the two patients revealing the echinostomatid eggs in their stools were proven to be infected with E. hortense and to be the second and third human cases of this fluke infection in Korea. Moroco oxycephalus harboured the metacercariae of E. hortense and appeared to be a new second intermediate host.
parasitology-helminth-trematoda ; Echinostoma hortense ; case report ; intermediate host ; rat ; Moroco oxycephalus ; Carassius carassius

The worm development and egg laying pattern of Echinostoma hortense(Trematoda: Echinostomatidae) were studied in albino rats and the brief clinical course was observed in human volunteers. A total of 21 rats were infected with 20-69 metecercariae each and two humans were with 7 and 27 metacercariae, which were collected from loaches. For recovery of worms, the rats were sacrificed at irregular intervals from the 6th to 150th day after infection and the human volunteers were treated with praziquantel and purged with magnesium salt on the 26-27th day. The stools of the rats and humans were examined for the eggs. The results were as follows: The worm recovery rate from the rats was not affected by the increase of infection time but varied individually; 9.1-50.0% (31.1% in average). From humans, 14.3% and 37.0% (32.4% in average) of challenged were recovered. In the rats, it was revealed that the worms rapidly grew for the first 14 days to become 7.59 mm in average length and 1.17 mm in average width but the growth became much slower thereafer until the 150th day; 7.95 mm in length on the 21th day, 9.04 mm on the 28th day, 10.21 mm on the 49th day and 12.62 mm on the 150th day. During the early stage of infection, the growth of genital organs(male or female) was expressed as sigmoid curves whereas non-genital organs(such as suckers) was simply as straight lines. The prepatent period of this fluke was 10-12 days in the rats and 16-17 days in men. After the start of oviposition, the egg production by the worms remarkably increased, reached maximum on the 32-33th day, followed by decrease thereafter. The maximum value of E.P.G./worm was 390. The major subjective symptoms in human volunteers were abdominal pain and diarrhea during the early stage of infection. The results show that human is as susceptible as the rats to E. hortense infection and the amount of egg production in the rats is greatly affected by the age of worms.
parasitology-helminth-trematoda ; Echinostoma hortense ; rat ; biology ; metacercaria

The infection status of the loaches, Misgurnus anguillicaudatus, with the metacercariae of Echinostoma hortense, was studied in Korea. A total of 154 loaches purchased at 4 local makets (Seoul, Kimhae, Naju-gun and Kangjin-gun) were examined their infection rate as well as the density and location of the metacercariae in the fish body. The results are as follews: The loaches carrying the metecercariae of E. hortense were 64 (41.6%) in total number and the metacercarial density ranged 1-29 per infected loach with an average value of 8.1. The highest infection rate and metacercarial density were obtained from the loaches purchased at Kangjin-gun, Jeonranam-do. The metacercaria of E. hortense were chiefly distributed in the distal intestinal wall and the adjacent mesentery, the perianal tissues, and the head and gill of the loaches examined. From the results, it is concluded that the loach is one of the important second intermediate hosts of E. hortense in Korea, and their infection rate and metacercarial density are considerably high.
parasitology-helminth-trematoda ; Echinostoma hortense ; Misgurnus anguillicaudatus ; metacercaria ; epidemiology ; intermediate host

Echinostomatid eggs were found from a 21-year old man, whole native village is Munkyong-gun, Kyongsangnam-do during fecal examination in October 1983. The eggs were detected again one week later concommitantly with the eggs of Clonorchis sinensis. He had no subjective symptoms related with these fluke infections. He was treated with praziquantel(Distocide) 20 mg/kg in single dose and purgated with magnesium salt. One echinostomatid fluke and 4 adults of C. sinensis were collected from the diarrheal stools. After morphological observation, the echinostomatid fluke was identified as Echinostoma hortense Asada, 1926. This is the first record on human E. hortense infection in Korea.
parasitology-helminth-trematoda ; Echinostoma hortense ; case report ; echinostomiasis ; praziquantel