[Prevalence Of Intestinal Parasites In Korea]

Prevention and Control Strategies for Parasitic Infections in the Korea Centers for Disease Control and Prevention

Korea is successfully controlled intestinal parasitic infections owing to economic development and high health consciousness. The Division of Vectors and Parasitic Diseases (formerly the Division of Malaria and Parasitology) is in the Center for Laboratory Control of Infectious Diseases of the Korea Centers for Disease Control and Prevention. It has been the governmental agency responsible for controlling and leading scientific research on parasitic diseases. The Division of Vectors and Parasitic Diseases has conducted and funded basic research and disseminated the research results to various medical fields, ultimately promoting public health in Korea. Among the noteworthy achievements of this division are the national surveillance of healthcare-associated parasitic infections, prevention and control for parasitic infections, and the elimination of lymphatic filariasis from Korea. On a broader scale, the division's research programs and academic supports were influential in preventing and treating infectious parasitic diseases through public policies and laws. In this review, we summarize the past and present role of the Division of Vectors and Parasitic Diseases in preventing and treating infectious parasitic diseases in Korea.

Prevalence of Clonorchis sinensis Infection among Residents along 5 Major Rivers in the Republic of Korea

Clonorchis sinensis is currently the most important parasite affecting public health problems in the Republic of Korea. We investigated the prevalence of C. sinensis infection among residents living along 5 major rivers in Korea. A total of 42,562 individual stool samples were collected from 37 localities and examined using the formalin-ether sedimentation technique. Helminth eggs were detected in 4,052 (9.5%) residents and 3,586 (8.4%) were infected with C. sinensis. The egg positive rate of C. sinensis in Nakdong, Seomjin, Geum, Yeongsan, and Han River was 11.7%, 9.9%, 6.5%, 3.1%, and 1.0%, respectively. The overall prevalence of clonorchiasis by sex was 11.2% in males and 6.2% in females. The age-prevalence was the highest in the 50-59 years band. It has been reconfirmed that the endemicity of clonorchiasis is higher in southern areas of Korea, especially along Nakdong and Seomjin Rivers. A combination of continuous control programs with health education initiatives is urgently required in these highly endemic areas of clonorchiasis in Korea.

Effect of a one-off educational session about enterobiasis on knowledge, preventative practices, and infection rates among schoolchildren in South Korea

Although health education has proven to be cost-effective in slowing the spread of enterobiasis, assessments of the effectiveness of health education to reduce infectious diseases specifically in children are rare. To evaluate the effect of health education on knowledge, preventative practices, and the prevalence of enterobiasis, 319 children from 16 classes were divided into experimental and control groups. Data were collected from May 2012 to March 2013. A 40-minute in-class talk was given once in the experimental group. There were significant differences over the time in the mean scores for children's knowledge of Enterobius vermicularis infection in the intervention group compared to the control group (p<0.001). After the educational session, the score for knowledge about E. vermicularis infection increased from 60.2 ± 2.32 to 92.7 ± 1.19 in the experimental group; this gain was partially lost 3 months later, decreasing to 83.6 ± 1.77 (p<0.001). Children's enterobiasis infection prevention practice scores also increased, from 3.23 ± 0.27 to 3.73 ± 0.25, 1 week after the educational session, a gain that was partially lost at 3 months, decreasing to 3.46 ± 0.36 (p<0.001). The overall E. vermicularis egg detection rate was 4.4%; the rates for each school ranged from 0% to 12.9% at screening. The infection rate at 3 months after the treatment sharply decreased from 12.3% to 0.8% in the experimental group, compared to a decrease from 8.5% to 3.7% in the control group during the same period. We recommend that health education on enterobiasis be provided to children to increase their knowledge about enterobiasis and improve prevention practices.

Heavy Hymenolepis nana infection possibly through organic foods: report of a case

We encountered a patient with heavy Hymenolepis nana infection. The patient was a 44-year-old Korean man who had suffered from chronic hepatitis (type B) for 15 years. A large number of H. nana adult worms were found during colonoscopy that was performed as a part of routine health screening. The parasites were scattered throughout the colon, as well as in the terminal ileum, although the patient was immunocompetent. Based on this study, colonoscopy may be helpful for diagnosis of asymptomatic H. nana infections.

Isospora belli Infection with Chronic Diarrhea in an Alcoholic Patient

Chronic diarrhea with a 35 kg weight loss (75 kg to 40 kg) occurred during 2 years in an alcoholic patient was diagnosed with Isospora belli infection in the Republic of Korea. The patient, a 70-year old Korean male, had been a heavy drinker for more than 30 years. He was admitted to the Seoul National University Hospital because of long-standing diarrhea and severe weight loss. He had an increased white blood cell (WBC) count with high peripheral blood eosinophilia (36.8-39.9%) and lowered protein and albumin levels but without any evidence of immunosuppression. A parasitic infection was suspected and fecal examination was repeated 3 times with negative results. Peroral endoscopy with mural biopsy was performed in the upper jejunum. The biopsy specimens revealed villous atrophy with loss of villi together with various life cycle stages of I. belli, including trophozoites, schizonts, merozoites, macrogamonts, and microgamonts. The patient was treated successfully with oral doses of trimethoprim 160-320 mg and sulfamethoxazole 800-1,600 mg daily for 4 weeks. A follow-up evaluation at 2.5 years later revealed marked improvement of body weight (68 kg), increased protein and albumin levels, and normal WBC count with low eosinophils (3.1%). This is the first clinical case of isoporiasis with demonstration of various parasitic stages in the Republic of Korea.

Seroprevalence of tissue invading parasitic infections diagnosed by ELISA in Korea

Seroprevalence of the IgG antibodies for Clonorchis sinensis, Paragonimus westermani, Taenia solium metacestode (cysticercus), and Spirometra erinacei plerocercoid (sparganum) was measured using enzyme-linked immunosorbent assay (ELISA) in sera of patients in Korea from 1993 to 2006. A total of 74,448 specimens referred nationwide from 121 hospitals revealed an IgG positive rate of 7.6% for the 4 parasites. The IgG positive rate (18.7%) for the 4 parasites in 1993 decreased gradually to 6.6% in 2006. Individual positive rate decreased from 5.2% (1993) to 1.6% (2006) for C. sinensis, from 2.8% (1993) to 1.1% (2006) for P. westermani, from 8.3% (1993) to 2.2% (2006) for cysticercus, and from 2.6% (1993) to 1.6% (2006) for sparganum. The positive rate was highest (21.2%) in the group of patients who ranged in age from 50-59 yr old, and in the group that was referred from the Seoul area (55.9%). In conclusion, our results suggest that tissue invading parasitic infections should always be included in differential diagnosis for patients with eosinophilia associated lesions of the central nervous system, liver, and lungs in Korea.

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 canine giardiosis in South Korea

This study was carried out a survey for the presence of Giardia intestinalis infections in dogs using a Giardia ELISA kit (SNAP) test, IDEXX Laboratories, Inc., Westbrook, ME). Four hundred and seventy-two dogs (190 males and 282 females) were examined for a G. intestinalis infection in four different provinces (Kyunggi, Chonnam, Kyungnam and Chungnam) and a Seoul city in South Korea. Slightly more male dogs (15.0%) than female (8.6%) dogs were affected, there was no significant difference between the two groups. The overall positive rates of G. intestinalis infection were 11.2%, 14.9% being found in the <2-year-old group, 8.7% in the 2-5 year-old group, and 2.1% in the >5-year-old group. X(2) analysis revealed a significantly higher prevalence (14.9%, P<0.05) in the <2-year-old group than in the other two groups, and a significantly higher prevalence in symptomatic dogs (47.6%, P<0.001) in asymptomatic dogs (7.7%). This study is the first large-scale survey of canine G. intestinalis infections in South Korea, and is expected provide a useful reference for clinicians. Giardia-infected dogs should be treated for hygienic management as well as to prevent dog to human transmission.

PALEOPARASITOLOGICAL REPORT ON THE STOOL FROM A MEDIEVAL CHILD MUMMY IN YANGJU, KOREA

Previous studies have successfully shown evidence for parasitic infections in human remains from various archaeological sites. However, in the case of Korea, since there have been very few paleoparasitological reports published, pre-20th century parasitic infection patterns remain obscure. Therefore, in order to partly fill this gap, we are reporting on a case of paleoparasitic infection from the feces of a 15th century child mummy from Yangju, Korea. In the course of the present study, we found the eggs of Clonorchis sinensis, Ascaris lumbricoides, and Trichuris trichiura in the feces of the mummy. Trichuris trichiura eggs were found in far greater numbers than other parasite eggs; in fact, intact bipolar plugs were clearly observed and even the larvae were still visible in some eggs. The eggs of C. sinensis and A. lumbricoides were also well preserved, though not in as great a number. Since we could find a number of well-preserved larvae-containing eggs, we are encouraged that successful extraction, amplification, and sequence determination of ancient DNA from the paleoparasite eggs might be possible in future studies. With additional paleoparasitological investigation using feces from Korean mummies, we hope that a history of parasite infection in Korea will be reconstructed.

[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.

Epidemiological studies of digenetic trematodes in Yongyang County, Kyungpook Province

The present study was undertaken to determine the endemicity of trematode infections in Yongyang County, Kyungpook Province, Korea. One hundred and seventy-seven out of 955 residents examined were found to be infected with one or more kinds of helminths. The prevalence rate was 18.5%. Among them, 70 were found to be infected with Clonorchis sinensis, 74 with Metagonimus sp. and 24 with both flukes. The eggs of Fasciolidae were demonstrated from two specimens. The prevalence rate of clonorchiasis in males was 12.6%, while that in females was 3.6% (p less than 0.05). The prevalence of metagonimiasis in males was 12.0% and was also significantly higher than 6.1% in females (p less than 0.05). The intensity of both infections was significantly heavier in males than in females. The prevalence of both flukes was higher in residents of over 30 years of age than in those below that age. No correlation was found between the intensity and the age group. Among eight species of the fresh-water fish collected at the Panbyon River, Zacco temmincki was found to be the most frequently and heavily infested with metacercariae of Metagonimus sp., and Gnathopogon atromaculatus alone was found to be infested with metacercariae of Clonorchis sinensis. The present results suggest that Yongyang area still remains endemic with Clonorchis sinensis and Metagonimus sp. infection.

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.

[Intestinal parasite infections among inhabitants in two islands of Tongyeong-gun, Kyeongsangnam-do]

This study was performed to evaluate the status of intestinal parasitic infections among the inhabitants in two islands (Chu-do and Doomi-do) of Tongyeong-gun, Kyeongsangnam-do (Province), from August to September, 1989. A total of 189 stool specimens was collected from the inhabitants of 3 villages and examined by Kato's cellophane thick smear and formalin-ether sedimentation techniques. Stoll's dilution egg counting technique was done for the quantitative examination of helminth eggs. The overall positive rate of intestinal parasites was 30.2%. The egg positive rate of Ascaris lumbricoides was 2.1%, that of Trichuris trichiura 24.3%, hookworm 2.1%, Trichostrongylus orientalis 0.5%, Clonorchis sinensis 1.1%, heterophyid 1.6%, and Taenia species 2.6%. The cyst positive rate of Giardia lamblia was 1.6% and that of Entamoeba coli 0.5%. In T. trichiura infection, the egg positive rate of females (29.9%) was much higher than that of males (17.2%). Among the age groups, 10-19 year group showed the highest infection rate, 32.4%. It was revealed that the prevalence of intestinal parasitic infections among the inhibitants of remote islands should be still high in comparison with ever-reported ones in urban or rural 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.

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

The present study was undertaken to evaluate the present status of intestinal parasitic infection in Seoul area, Korea. During the period from June 1985 to July 1986, a total of 5,251 stool samples were collected in Department of Clinical Pathology, Hanyang University Hospital and examined by formalin-ether sedimentation technique once for helminth ova and protozoan cysts. The results were summerized as follows: The overall egg positive rate of intestinal helminthes was 2.53 per cent; and 1.43 per cent for Clonorchis sinensis, 0.7 per cent for Trichuris trichiura, 0.13 per cent for Metagonimus yokogawai, 0.06 per cent for hookworm, and 0.02 per cent for Ascaris lumbricoides, Diphyllobothrium latum and Hymenolepis nana, respectively. The overall cyst positive rate of intestinal protozoa was 1.07 per cent. Cyst positive rate was 0.06 per cent for Entamoeba histolytica and 0.13 per cent for Giardia lamblia, respectively. Higher prevalence of intestinal parasitic infection was observed in male and in 21-50 year-old groups. The highest prevalence of Clonorchis sinensis infection was observed in 40th age group(3.4 per cent), and male (2.3 per cent) was more infected than female (0.7 per cent) in general.

[Evaluation of Giardia lamblia detection method in stool specimens fixed with SAF solution]

The present study has been designed as a basic study on laboratory diagnosis of giardiasis and to demonstrate a more effective method for the detection of Giardia lamblia cyst with the inherent advantages of minimizing both the number of stool examinations required and the interval of stool collections for estimating the real state of prevalence in the shortest time possible. There were 3 subject groups of 75 children each currently residing in an orphanage in Gunsan city, Jeonbuk province from which stool specimens were collected every day, every other day, and every 3 days. The procedure is as follows: Resuspend the fixed sample after fixation with SAF solution. Centrifuge the sediment for 1 min. at 2,000 rpm after straining through gauze into a tube. Divide the sediment into 3 parts and use them for direct fecal smear, formalin-ether concentration (MGL) and zinc sulfate (ZnSO(4)) floatation techniques. The results are summarized as follows: Overall infection rate after 10 trials showed a 60 percent positive indication. The positive rate among children under 4 years old was significantly higher than the rate in children over 4 years old. No significant difference in rate by sex was observed. The results of examinations by direct fecal smear and MGL techniques appeared more accurate than that obtained by ZnSO(4) floatation method as indicated by a higher positive rate. Of all three methods concerned, combinations of two demonstrated a higher positive rate than that shown by any one alone. In three consecutive examinations under varying conditions such as different days, the cyst detection rate by MGL technique indicated 83 percent. In 5 examinations under the same varying conditions, the indicated rate was 94 percent. The interval of stool collection proved to be insignificant for the cyst detection rate. In conclusion, both MGL method and modified fecal direct smear can provide a good cyst detection rate of G. lamblia provided that more than 3 consecutive examinations of stool under varying conditions are carried out.

Epidemiological Studies On Ascaris Lumbricoides Reinfection In Rural Communities In Korea II. Age-Specific Reinfection Rates And Familial Aggregation Of The Reinfected Cases

Epidemiological studies on the reinfection pattern of Ascaris lumbricoides were undertaken by means of blanket mass chemotherapy and worm collection in a rural village in Korea, during 1977~1980. The study objectives were to determine the age(sex)-specific reinfection rate during 2, 4, 6 and 12 months through repeated mass chemotherapy with pyrantel pamoate, and to observe the familial aggregation tendency of the reinfected cases. The results obtained are as follows: 1. The age(sex)-reinfection curve revealed that the reinfection rate is much higher in younger individuals than in olders in all of 4 kinds of interval chemotherapy groups. The highest reinfection rate and the highest burden of reinfected worms were observed in preschool childen, followed by primary school students. Such fluctuation in the age-specific reinfection rates was more pronounced in males than in females. 2. There was noted a significant tendency of familial aggregation among the reinfected cases. It is suggested that reinfection occurs never randomly but preferably to the members of certain household families. From these reinfection analyses, it is inferred that the principal mode of A. lumbricoides transmission in the surveyed rural area is likely to be of 'dooryard type', in which case childen and certain family members are more preferably reinfected. It is also suggested that the preschool childen should be included in the primary targets of mass control programme.

[A Survey On The Prevalence Of Intestinal Protozoan Cysts In Jeonlanam Do, Korea]

A survey on the prevalence of intestinal protozoan cysts was conductcd in Jeonlanam Do (Province), Korea in 1981. A total of 4,116 specimens was collected from 2,035 male and 2,086 female inhabitants in 4 urban and 7 rural areas. Each case was selected randomly to represent 1,000 inhabitants referred to the census in 1980. Formalin-Ether sedimentation technique was employed to concentrate the cysts and one Lugol's iodine stained smear was examined for each case. The results were summarized as follows: 1. The cases who passed out protozoan cysts of any kind were 9.1 % out of total 4,116 examined, and cumulative positive rate was 11.0 %. Among the positive cases, 16.5 % were infected by two or more species of protozoa. 2. Total 5 species of cysts were detected and the positive rates were as follows; Entamoeba histolytica 1.4 %, E. Coli, 4.9 %, Endolimax nana 2.5 %, Iodamoeba butschlii 0.4 % and Giardia lamblia 1.9 %. 3. The cyst positive rates varied greatly by the surveyed area. The positive rate in rural area was 11.6 % compared with 5.7 % in urban area. The highest rate was found 14.5 % in Gurye Gun (County) and the lowest 3.6 % in Mogpo Si (City). 4. Female showed much higher positive rate than male as 11.8 % compared with 6.4 % and the cumulative rate 14.2 % and 7.6 % respectively. By age group, the rate was highest as 13.9 % in 40~49 years and next 12.5 % in over 60 years group. The cyst prevalence rate diminished remarkably in Jeonlanam Do compared to previous records. However, the finding that 20.2 % of females of 40 years were the carrier of protozoan cysts was an important information in public health point of view.

[The Status Of Intestinal Protozoan Infections In Inhabitants Of Gangweon-Do, Korea]

To evaluate the status of intestinal protozoan infections in inhabitants of Gangweon-Do, Korea, a total of 1,310 stool specimens (male 669, female 641) was collected from 2 cities and 3 counties. They were examined routinely 1 time by the method of formalin-ether sedimentation technique. The results were as follows: 1. The positive rate for any kind of the intestinal protozoan cysts was 8.9 %. 2. A total of 6 kinds of the intestinal protozoan cysts were detected. The prevalence rate of each protozoa were; E. histolytica 0.8 %, E. coli 7.6 %, E. nana 1.4 %, I. butschlii 0.2 %, G. lamblia 0.5 % and C. mesnili 0.5 %. 3. Sogcho-city showed the highest positive rate as 15.2 %, Myeongju county was the next as 11.3 % and Weonju-city showed the lowest positive rate as low as 3.9 %. 4. By age, the highest positive rate was found in 20-29 age group(12.4 %). Female (9.5 %) showed a slight higher positive rate than male (8.4 %).

[An Epidemiological Study On Zoonoses In Korea]

Helminthic zoonoses are of significant importance to the public health and to the socioeconomic consequences especially in lost-meat, animal products and animal labor. For past several decades in Korea, it has been recognized that endoparasitic infections among domestic animals are extremely common and many of the helminth parasites of man have been acquired from, or are shared with domestic animals. However, there was no survey of a nationwide scale on the prevalence of animal helminthiasis; and control measures are also not satisfactory. Furthermore, because of the remarkable increase in the demand, number of domestic animals and pets is rapidly increasing in these days. Therefore, an extensive study on zoonotic helminths was carried out from July 1980 throughout August 1981 to understand the present status and parasite-host relationship from the epidemiological viewpoont. A total of 13,685 fecal specimens of cattles, sheeps, pigs, dogs and cats was collected from 26 localities in the country. The specimens were examined by formalin-ether centrifugal sedimentation technique. The results are summarized as follows: 1. Of 13,685 specimens examined, 9,808(71.7 %) were positive for helminth parasites. The positive rates were 99.0 % in cattles, 86.5 % on sheeps, 85.4 % in pigs, 35.4 % in dogs, 15.1 % in cats. 2. Single infection showed the highest rate (60.0 %), and double infection(27.5 %), triple(8.1 %), quadruple(2.8 %), quintuple(1.5 %) and hexad(0.1 %) were in decreasing order. 3. In the present study, 18 species zoonotic helminths were found: 11 nematodes, 6 trematodes and 1 cestode. 4. According to province, Cheju revealed the highest rate 84.8 %, then Kyungnam 77.5 %, Jeonnam 75.6 %, Jeonpuk 75.4 %, Kyonggi 75.2 %, Chungnam 71.7 %, Chungpuk 70.6 % and Kangwon 64.2 % were in decreasing order and Busan and Seoul showed 70.4 % and 58.1 %, respectively. 5. Rural area showed slightly higher rate (74.7 %) than urban area (68.5 %), and rates of mountainous area (70.4 %) and plain area (71.1 %) are very similar. 6. According to animal, helminths species and positive rates appeared in: Cattles: 6 nematodes and 3 trematodes; Strongyles 26.4 %, Neoascaris vitulorum 24.1 %, Trichuris ovis 12.0 %, Nematodirus sp. 6.3 %, Srongyloides papillosus 5.1 %, Capillaria bovis 0.02 %, Paramphistomum sp. 41.5 %, Fasciola hepatica 33.2 % and Eurytrema pancreaticum 29.7 %. Sheeps: 3 nematodes and 2 trematodes: Strongyles 33.0 %, S. papillosus 26.9 %, Nematodirus sp. 14.6 %, F. hepatica 31.7 % and E. pancreaticum 19.6 %. Pigs: 5 nematodes and 2 trematodes: Strongyles 43.1 %, Ascaris suum 29.0 %, Metastrongylus apri 20.3 %, Trichuris suis 14.0 %, Strongyloides ransomi 12.1 %, Clonorchis sinensis 1.4 % and Paragonimus westermani 0.9 %, Dogs: 4 nematodes and 3 trematodes and 1 cestode: Toxocara canis 14.4 %, Trichuris vulpis 9.5 %, Ancylostoma caninum 8.0 %, Toxascaris leonina 4.0 %, C. sinensis 2.4 %, Metagonimus yokogawai 1.3 %, P. westermani 0.8 % and Spirometra sp. 0.9 %, Cats: 2 nematodes, and 3 trematodes and 1 cestode: Toxocara cati 7.7 %, Ancylostoma tubaeforme 3.1 %, C. sinensis 1.9 %, P. westermani 1.4 %, M. yokogawai 1.2 % and Spirometra sp. 0.7 %.

[An Epidemiological Note On The Taeniasis In Korea]

The present study was undertaken to evaluate the prevalence rate of Taenia spp. infection and distribution of taeniasis caused by T. solium among Koreans in several localities in Korea during the period from 1977 to 1980. A total of 1,946 stool specimens collected from students and inhabitants of Chungcheong Bug Do and Gyeongsang Nam Do were examined by cellophane thick smear method. Among them, 40 persons were detected as Taenia egg positive cases. The overall positive rate of Taenia spp. shows 2.1 %. The prevalence rate of male (2.3 %) is relatively higher than that of female (1.4 %). In order to observe the distribution of Taenia solium infection, the whole worms or a part of proglottids of Taenia spp. were collected from the stools of egg positive cases by normal defecation or anthelmintic treatment. For the species identification, expelled proglottids were examined microscopically by the number of branches of the uterus, presence of a vaginal sphincter or the accessory ovarian lobe etc. Among 199 egg detected cases in this study 59 (39.1 %) out of 151 cases in Seoul, 12(40.0 %) of 30 cases in Gyeongsang Nam Do and 2 (25.0 %) from 8 taeniasis cases in Cheju Do were infected with T. solium. But none of T. solium infection was found from 10 egg positive cases in Chungcheong Bug Do. As a whole, the composition of species shows 36.7 per cent of T. solium infection and 55.8 % of T. saginata infection, and in 7.5 per cent the species were not identified.

Demonstration Of Entamoeba Histolytica Cyst From Urban And Rural School Children

School children between 6 to 12 years of age were studied for the presence of Entamoeba histolytica cysts in a period of 6 months, form March to August 1980. Fecal specimens collected form urban and rural children were examined first by the Lugol stained technique and then by the Faust's iron alum hematoxylin method. A total of 731 specimens were examined. Of these 26.9 per cent, 197 specimens, harbored the cysts. The demonstration rate for the cysts by age group varied from 19.6 to 43.5 per cent. The demonstration rate in boys was 24.4 per cent and in girls 29.8 per cent. Similarily, the rate in urban and rural area was 32.4 and 24.1 per cent, respectively. It was found in the present study that there were no significant differences in the age and sex rates of demonstration between urban and rural children but there was a predominance of the small race of Entamoeba histolytica over the large race.

Epidemiological studies of Clonorchis sinensis in vicinity of river Taewha, Kyungnam province, Korea

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 % 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 % 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.

[Studies on the incidence of the intestinal protopozoa in the mountainous area of Chollapuk-do]

This study was undertaken in order to elucidate the prevalences of the intestinal protozoan infection according to localities and the mode of the infestation in the mountainous area of Chollapuk-do, Korea during the year 1970-1971. 8,508 of fecal samples were collected among the inhabitants of the mountainous area, which covered 18 Myens(=Township) from 6 Guns(=County) in the eastern part of Chollapuk-do. Most of the inhabitants of this area were engaged in farming and living under lower economic and poor sanitary conditions. The samples were examined twice repeatedly by iodine stained direct fecal smear method. For the study on the mode of infestation, with the exception of drinking water, the zinc sulfate floatation technic was applied for the examinations of hog-feces, manure heap, garden soil, sewage, dishtowel, dust in room and floor, house fly and house rat. The results were summarized as follows: 1. Among total 8,508 fecal specimens examined, 3,152(37.6 %) were positive for the intestinal protozoa: E. histolytica 9.8 %, E. coli 25.6 %, E. nana 7.2 %, G lamblia 6.8 %, I. butschlii 0.6 %, and C. mensnili 0.7 %. 2. A single infection of the intestinal protozoa was the highest(68.3 %), and double infection(22.3 %) triple, quadruple and quintuple infections were in decreasing order. 3. The highest distribution (39.8 %) was observed in the group aging 41-50, and the lowest (27.3 %) in the group above 61. The groups under 10 years showed a relatively high positive rate among all age groups. 4. Sexual distribution of protozoan infection showed slightly higher rate (38.6 %) in male than that (35.4 %) of female. 5. Jangsoo-gun showed the highest positive rate (42.9 %) and Namwon-gun was the lowest (32.5 %). The prevalence of E. histolytica showed the highest (11.6 %) in Imsil-gun and the lowest (6.9 %) in Jangsoo-gun. 6. E. histolytica cysts were found 9.1 % among total 99 samples of hog feces, 4.8 % among 78 samples of manure heap, 0.6 % among 164 samples of fingernail dirt, 5.3 % among 57 samples of drinking water, 15.8 % among 19 samples of sewage, 7.1 % among 42 samples of dishtowel, 0.1 % among 780 samples of house fly and 5.0 % among 40 samples of house rat.