[Intestinal parasite survey in Seoul by stool examination at Hanyang University Hospital]

Parasitic infections based on 320 clinical samples submitted to Hanyang University, Korea (2004-2011)

We analyzed 320 clinical samples of parasitic infections submitted to the Department of Environmental Biology and Medical Parasitology, Hanyang University from January 2004 to June 2011. They consisted of 211 nematode infections, 64 trematode or cestode infections, 32 protozoan infections, and 13 infections with arthropods. The nematode infections included 67 cases of trichuriasis, 62 of anisakiasis (Anisakis sp. and Pseudoterranova decipiens), 40 of enterobiasis, and 24 of ascariasis, as well as other infections including strongyloidiasis, thelaziasis, loiasis, and hookworm infecions. Among the cestode or trematode infections, we observed 27 cases of diphyllobothriasis, 14 of sparganosis, 9 of clonorchiasis, and 5 of paragonimiasis together with a few cases of taeniasis saginata, cysticercosis cellulosae, hymenolepiasis, and echinostomiasis. The protozoan infections included 14 cases of malaria, 4 of cryptosporidiosis, and 3 of trichomoniasis, in addition to infections with Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Endolimax nana, Giardia lamblia, and Toxoplasma gondii. Among the arthropods, we detected 6 cases of Ixodes sp., 5 of Phthirus pubis, 1 of Sarcoptes scabiei, and 1 of fly larva. The results revealed that trichuriasis, anisakiasis, enterobiasis, and diphyllobothriasis were the most frequently found parasitosis among the clinical samples.

Analysis of parasitic diseases diagnosed by tissue biopsy specimens at KyungHee Medical Center (1984-2005) in Seoul, Korea

We analyzed parasitic diseases diagnosed by tissue biopsy specimens at KyungHee Medical Center (KMC) from 1984 to 2005. The total number of parasite infection cases was 150 (0.07%) out of the total 211,859 biopsy specimens submitted for histopathological examinations. They consisted of 62 cysticercosis, 23 sparganosis, 16 paragonimiasis, 15 amebiasis, 11 anisakiasis, 11 clonorchiasis, 3 ascariasis, 2 scabies, 2 enterobiasis, 2 trichuriasis, 1 leishmaniasis, 1 taeniasis, and 1 thelaziasis. Out of 62 cysticercosis cases, 55 were detected in subcutaneous tissues or the central nerve system. Eighteen out of 23 sparganosis cases were involved in muscular and subcutaneous tissues. In most anisakiasis cases, the involved organ was the stomach. The lung and the pleura were the most common site of paragonimiasis. The incidence of parasitic diseases during the first 5 years (1984-1988) was the highest of all observed periods. After 1989, similar incidences were shown throughout the period. Whereas cysticercosis was diagnosed in 34 cases during 1984-1988, no case has been diagnosed since 2000. In the case of sparganosis, the chronological incidence was almost uniform throughout the period 1984-2005. Paragonimiasis showed a similar tendency to cysticercosis. In gender and age distribution of parasitic diseases, men showed higher incidence rates than females, and the age groups of the 40s or older indicated higher infection frequencies than other age groups. Therefore, these results are a significant report to appear the tendency of human parasitic disease diagnosed by tissue biopsy in association with parasitosis at KMC in Seoul.

Review of zoonotic parasites in medical and veterinary fields in the Republic of Korea

Zoonotic parasites are animal parasites that can infect humans. The major zoonotic protozoa in the Republic of Korea are Babesia bovis, Chilomastix mesnili, Cryptosporidium parvum, Endolimax nana, Entamoeba coli, Entamoeba hitolytica, Giardia lamblia, Iodamoeba bütschlii, Pneumocystis carinii, Sarcocystis cruzi, and Toxoplasma gondii. The major zoonotic helminths in Korea include trematodes, cestodes, and nematodes. Trematodes are Clonorchis sinensis, Echinostoma hortense, Echinostoma spp., Fasciola hepatica, Heterophyes nocens, Metagonimus yokogawai, and Paragonimus westermani. Cestodes are Diphyllobothrium latum, Dipylidium caninum, Echinococcus granulosus, Hymenolepis nana, Raillietina tetragona, sparganum (Spirometra spp.), Taenia saginata, T. solium, and T. asiatica. Nematodes are Ancylostoma caninum, Brugia malayi, Capillaria hepatica, Dirofilaria immitis, Gnathostoma dololesi, Gnathostoma spinigerum, Loa loa, Onchocerca gibsoni, Strongyloides stercoralis, Thelazia callipaeda, Trichinella spiralis, Trichostrongylus orientalis, Trichuris trichiura, and Trichuris vulpis. The one arthropod is Sarcoptes scabiei. Many of these parasites have disappeared or were in decline after the 1990's. Since the late 1990's, the important zoonotic protozoa have been C. parvum, E. nana, E. coli, E. hitolytica, G. lamblia, I. buetschlii, P. carinii and T. gondii. The important zoonotic helminths have been C. sinensis, H. nocens, M. yokogawai, P. westermani, D. latum, T. asiatica, sparganum, B. malayi, T. orientalis, T. callipaeda and T. spiralis. However, outbreaks of these parasites are only in a few endemic areas. The outbreaks of Enterobius vermicularis and head lice, human parasites, have recently increased in the kindergartens and primary schools in the Republic of Korea.

A nationwide survey on the prevalence of intestinal parasitic infections in the Republic of Korea, 2004

National surveys on the prevalence of intestinal parasitic infections have been carried out every 5-7 years since 1971 in the Republic of Korea in order to establish control measures. The present nationwide survey was conducted from June to December 2004. The 10% population sampling data of Population and Housing Census by the Korean government in 2000 was used as the survey population. One sample was selected randomly from each of the 22,858 registered subjects, and a total of 20,541 people were ultimately included in this survey. Fecal examinations were performed by the cellophane thick smear and saturated brine flotation techniques. Pinworm infection was examined by cello-tape anal swab method. This survey also included a questionnaire study for a socioeconomic analysis. The total helminth egg positive rate was 3.7%, and the estimated total positive number among nationwide people was 1,780,000. The rates in urban and rural areas were 3.1% and 6.8%, respectively. As the total egg positive rate in the 6th survey in 1997 was 2.4%, the present survey showed that there was a considerable degree of increase in the prevalence rate of intestinal parasitic infections over the 7-year period following the 6th survey. The largest increases occurred in the egg positive rates of Clonorchis sinensis and heterophyids including Metagonimus yokogawai.

Prevalence of clonorchiasis in patients with gastrointestinal disease: A Korean nationwide multicenter survey

AIM: To investigate prevalence of Clonorchis sinensis in patients with gastrointestinal symptoms, and the relation of the infection to hepatobiliary diseases in 26 hospitals in Korea.

METHODS: Consecutive patients who had been admitted to the Division of Gastroenterology with gastrointestinal symptoms were enrolled from March to April 2005. Of those who had been diagnosed with clonorchiasis, epidemiology and correlation between infection and hepatobiliary diseases were surveyed by questionnaire.

RESULTS: Of 3080 patients with gastrointestinal diseases, 396 (12.9%) had clonorchiasis and 1140 patients (37.2%) had a history of eating raw freshwater fish. Of those with a history of raw freshwater fish ingestion, 238 (20.9%) patients had clonorchiasis. Cholangiocarcinoma was more prevalent in C. sinensis-infected patients than non-infected patients [34/396 (8.6%) vs 145/2684 (5.4%), P = 0.015]. Cholangiocarcinoma and clonorchiasis showed statistically significant positive cross-relation (P = 0.008). Choledocholithiasis, cholecystolithiasis, cholangitis, hepatocellular carcinoma, and biliary pancreatitis did not correlate with clonorchiasis.

CONCLUSION: Infection rate of clonorchiasis was still high in patients with gastrointestinal diseases in Korea, and has not decreased very much during the last two decades. Cholangiocarcinoma was related to clonorchiasis, which suggested an etiological role for the parasite.

Clonorchiasis and cholangiocarcinoma: etiologic relationship and imaging diagnosis

Despite a gradual decrease in prevalence, clonorchiasis is still prevalent in East Asia. A large and compelling body of evidence links clonorchiasis and cholangiocarcinoma, although the mechanisms involved are not completely understood. Clonorchiasis induces biliary epithelial hyperplasia and metaplasia, and this could facilitate at least one stage of the carcinogenesis, which is promoting effect. In areas of endemic infection, more clonorchiasis cases are now diagnosed incidentally during radiological examinations such as cholangiography, ultrasonography, and computed tomography. Radiological findings are regarded as pathognomonic for clonorchiasis since they reflect the unique pathological changes of this disorder. These radiological examinations currently play important roles in the diagnosis, staging, and decision-making process involved in the treatment of cholangiocarcinoma. The morphological features and radiological findings of clonorchiasis-associated cholangiocarcinoma are essentially combinations of the findings for the two diseases. The morphological features of clonorchiasis- associated cholangiocarcinoma, observed in radiological examinations, do not differ from those of the usual cholangiocarcinoma. In patients diagnosed with or suspected to have clonorchiasis, radiological findings should be carefully scrutinized for occult cholangiocarcinoma.

[Five human cases of Diphyllobothrium latum infection through eating raw flesh of redlip mullet, Liza haematocheila]

A total of 32 human diphyllobothriasis cases have been reported so far in Korea, excluding 21 egg-positive cases from stool examinations. Authors experienced five more human cases of Diphyllobothrium latum infection, especially infected due to eating raw flesh of redlip mullet, Liza haematocheila. Five cases were neighbors residing in the Puchon area, Kyonggi-do, who ate raw mullets (L. haematocheila) in a party in February 1996. The mullets were purchased at the Noryangjin fisheries market in Seoul. All of cases (2 males and 3 females) were 35 to 43 years old and healthy with the body weight range of 56-62 kg. They complained about gastrointestinal trouble and abdominal discomfort, but were in normal ranges of their hematology and urinalysis data. None revealed any sign of anemia. The patients experienced natural discharge of a chain of segments before, and showed diphyllobothriid eggs in their stool specimens when they visited our laboratory. They were administered with praziquantel (15 mg/kg of body weight) and 30 g of magnesium sulfate as a purgative. Two whole worms with the scolices (310-340 cm in length; 8-13 mm in width) were expelled each from two out of five cases after anthelmintic treatment, and the others expelled the parts of strobilae without scolex. The worms were identified as D. latum, based on the following biological characters: external morphologies, coiling of uterus, the number of uterine loops, position of genital opening, morphologies of cirrus, cirrus sac and seminal vesicle on the histological sections, position of vagina and uterine pore, and microscopical and SEM morphologies of the eggs.

[Second report on intestinal parasites among the patients of Seoul Paik Hospital (1984-1992)]

The results of fecal examination for helminth eggs and protozoan cysts in Seoul Paik Hospital during 1984-1992 are reported. Fecal specimens of a total of 52,552 out- or inpatients were examined by formalin-ether sedimentation and/or direct smear method. The overall egg positive rate of helminths was 6.5% and the cyst positive rate of protozoa 2.5%. The egg positive rate (number of positive cases) for each species of helminth was; Clonorchis sinensis 3.2% (1,667), Trichuris trichiura 2.0% (1,089), Metagonimus yokogawai 1.2% (613), Ascaris lumbricoides 0.2% (100), Trichostrongylus orientalis 0.1% (34), Taenia spp. 0.05% (28), Hymenolepis nana 0.03% (18), hookworms 0.03% (17), Paragonimus westermani 0.02% (12), Echinostoma spp. 0.03% (12), Enterobius vermicularis 0.02% (10), Strongyloides stercoralis (larvae) 0.01% (6), and Diphyllobothrium latum 0.004% (2). The cyst positive rate (number of positive cases) for each protozoan was; Entamoeba coli 1.1% (588), Endolimax nana 0.8% (402), Giardia lamblia 0.3% (173), Entamoeba histolytica 0.3% (164), and Trichomonas hominis (trophozoites) 0.004% (2). Viewing from the data of 9 years, it was evident that the prevalence of soil-transmitted helminths such as A. lumbricoides and T. trichiura has been decreasing remarkably, while that of snail-transmitted helminths such as C. sinensis and intestinal protozoans has not.

Turnover of biliary epithelial cells in Clonorchis sinensis infected rats

We performed bromodeoxyuridine (BrdU) staining to observe the proliferation pattern of epithelial cells on the biliary mucosa in Clonorchis sinensis infection. Albino rats were infected with 100 metacercariae each and their livers were processed for histopathological observation after BrdU injection. Five to six sites in the liver of a rat were selected for paraffin section, and stained immunohistochemically to visualize BrdU incorporating cells. The flukes were mainly in the common bile duct and right or left hepatic bile ducts. The proportion of stained epithelial cells in the infected bile ducts where the worms were found on the section was 2.9-10.2% at 1 week after infection, 7.3-12.8% at 2 weeks, 7.3-13.4% at 5 weeks, and 8.4-14.8% at 15 weeks while in the non-infected ducts 0 to 2.7% cells were stained. The stained cells were mainly at the base of the mucosal layer. It is suggested that mucosal epithelial cells of the bile ducts infected with C. sinensis become hyperplastic mainly by direct and local stimulation of the worms.

Cestode infections in Korea

Epidemiological surveys concerning cestodes of medical importance in Korea have been sporadically reported by many workers. Among various parasitic infections, cestode infections occur less frequently than other helminthiases, but they often cause serious clinical complications. Cestodes reported so far in Korea belong to the Order Pseudophyllidea or Cyclophyllidea (Subclass Cestoda), i.e., Diphyllobothrium latum, D. yonagoense, Spirometra erinacei, sparganum, Hymenolepis diminuta, H. nana, Mesocestoides lineatus, Taenia saginata, T. solium, metacestode of T. solium (cysticercus), and Echinococcus granulosus. The present paper is a brief review of the literature concerning these cestode infections in Korea. Taeniases by T. saginata or T. solium are prevalent cestode infections in Korea, and cysticercosis by T. solium often reveals serious clinical manifestations. H. nana infection is relatively rare, showing 0.22% egg positive rate in a nationwide survey in 1986. Sparganosis by the plerocercoid larva of Spirometra is not an uncommon cestode infection in man, and 16 kinds of animal hosts including the snakes and frogs have been reported. D. latum infection has been an uncommon intestinal parasitosis, but it tends to increase nowadays. Most of human hydatidosis cases have been recognized as imported ones from outside Korea, but one case was proven indigenous. Other 4 kinds of cestodiases are extremely rare in Korea and only a few cases have been recorded.

[A survey on the epidemiological factors of clonorchiasis in the Pohang industrial belt along the Hyungsan river, Kyongsangbuk-do]

The employees at the Pohang industrial area, where Clonorchis sinensis has been known to be endemic along the Hyungsan River, were examined parasitologically for clonorchiasis and a part of the infected cases were surveyed with a questionnaire to outline the recent infection status of C. sinensis and epidemiological parameters in the area. Total of 3,180 cases were tested by intradermal inoculation of C. sinensis antigen (Green Cross Co., Korea), and 834 (26.2%) were found positive. Out of the positive cases, 598 were subjected to fecal examination for helminth ova. The examination revealed 129 (21.6%) ova positive cases of C. sinensis, and Trichuris trichiura 1.7%, Ascaris lumbricoides 0.3%, and Metagonimus yokogawai 0.2%. The questionnaire analysis showed some significant differences between the infected and non-infected (control) groups. The infected cases were less educated than the control, and they lived at the closer area to the river, and most of them lived there over 20 years. Also they preferred eating raw fresh water fish. Most of the detected cases were treated with praziquantel and found negative for the eggs in 85.3% of them 1 year after the treatment. The present data reveal markedly decreased endemicity of clonorchiasis compared with previous prevalence rates but still clonorchiasis is endemic in the Hyungsan river basin. A comprehensive measure including case detection, treatment and education for parasite control should be applied to control clonorchiasis in such endemic areas.

Status of intestinal parasitic infections in a remote island, Yondo, Jeonranam-do: province

This study was performed to observe the present status of intestinal parasitic infections in a remote island, Yondo, located in southern part of Jeonranam-do(province), Korea. In February and May 1988, total 1,011 individual stool samples were collected and examined for intestinal helminths and protozoa using formalin-ether centrifugal sedimentation technique. The results are summarized as follows: Of 1,011 ingabitants examined, 398(39.4%) were positive for intestinal parasites. Helminth positives were 372(36.8%), and protozoan cyst positives were 56(5.5%). Ten species of parasites were found. Trichuris trichiura revealed the highest infection rate of 27.5%, Ascaris lumbricoides 17.4%, Taenia sp. 5.8%, Entamoeba coli 3.3%, Giardia lamblia 1.5%, Endolimax nana 0.8%, Hymenolepis nana 0.4%, hookworm 0.2%, Trichostrongylus orientalis 0.2%, and Entamoeba histolytica 0.2%, respectively. The female group showed higher positive rate (44.0%) than males (34.7%). Also, higher positive rates were observed among adults as compared with the group younger than 10 years old. Average value of E.P.G. was 1,876(range 200-17,800) in A. lumbricoides positives, and 327(range 200-1,600) in T. trichiura positive cases. In helminth egg positive cases, single infection was 63.4%, double infection 34.7%, and triple infection 1.9%, respectively. Among protozoan cyst positives, single infection was 94.6%, and double infection was 5.4%. The present study revealed that the prevalence of intestinal parasites among inhabitants in Yondo island is still so high that special control measures should be performed.