This study was undertaken to estimate the reinfection incidence of Ascaris lumbricoides after biannual blanket mass chemotherapy and to figure out the characteristic seasonal fluctuation pattern in a Korean rural village. A total of 612 residents from 4 Ri's of Hwasung Gun, Kyunggi Do, Korea was selected and divided into 6 groups according to hamlets, each of which consisted of about 100 inhabitants. Each group received blanket biannual mass chemotherapy with 10 mg/kg of pyrantel pamoate respectively in each month, during the period from April 1977 to September 1978 (Group A-April and October 1977 and April 1978, Group B-May and November 1977 and May l978, and so on). Beforehand Ascaris infection status was evaluated by examining eggs and worms expelled exactly after the first mass chemotherapy checked during the first 6 months and the reinfection incidences were estimated in follow-up examinations during next l2 months by the above two kinds of methods and by detection of young Ascaris positive cases. Young Ascaris was defined as worm shorter than l3 cm and lighter than 500 mg and considered to have introduced to human host during the period from the previous 2 months to 2 weeks. The results were summarized as follows: Beforehand infection rate with Ascaris were 42.3 percent (34.4-50.6 percent by group) by egg detection and 46.2 percent (36.2-51.9 percent by group) by worm detection methods in average. Number of worms per infected case was 2.7 (1.5-4.2 by group) in average. Reinfection rates estimated by egg detection ranged from 8.0 to 3l.5 percent (l6.9 percent in average) in the first follow-up period and from 14.0 to 20.0 percent (l7.5 percent in average) in the second follow-up. Seasonal fluctuation was found marked and there were roughly two peaks, of which the larger appeared from February to March and the smaller from August to September. Reinfection rates by worm detection method ranged from 20.6 to 34.9 percent(25.7 percent in average) and from 14.3 to 21.9 percent (19.6 percent in average) in respective follow-up examinations. Seasonal fluctuation was also observed and the peak incidence appeared one month earlier than those made by egg positive conversion. Number of worms per infected case decreased to 1.6 in average in both follow-up. Young Ascaris detection rates ranged from 6.0 to 12.9 percent (9.4 percent in average) and from 2.3 to 5.8 percent (3.8 percent in average) in respective follow-up. Seasonal fluctuation was also observed. From January to February, the positive rates were up to 12.9 percent and 12.7 percent respectively, which formed the higher peak. Lower one was observed during July to August. From the above results, the actual time of Ascaris reinfection were November to December for the higher peak and May to June for the lower one in Korean population. Pickled vegetable was suggested as a most probable source of Ascaris reinfection during late autumn to winter season.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; reinfection ; epidemiology

Human sparganosis in Korea was discussed on the bases of five human cases experienced by the present authors and 58 case records already reported by many previous authors, in aspects of epidemiology and clinical features. Sparganosis is not infrequent tissue helminthiasis now in Korea and the incidence has been evidently increased during past 10 years. It might be interpreted that improved medical delivery system and health care exposed the hidden but prevalent disease. The distribution of sparganosis in Korea is apparently subdivided into three major endemic areas; Kyunggi Do, Kyungsang Do and Hamkyung Nam Do. Although scanty in other areas of Korea, the distribution of this disease is presumably throughout the whole peninsula of Korea except Cheju Do. The majority of human cases of sparganosis in Korea has revealed raw consuming of snakes for treatment of tuberculosis, syphilis and joint pain, for tonics and for the belief of special nutrition among very limited group of Korean population. Because of this kinds of mode of infection, comprising four fifths of all cases, the majority of cases detected were male adult consisting of about 70% of total cases. And drinking of untreated water in rural area where no protective, sanitary measures for water sources were provided in the past, seems another important causes of infection especially in women and children in Korea. Thus it may be concluded that sparganosis in Korea is concluded by eating of infective stages per os voluntarily or involuntarily, but not through the direct invasion. Clinically, subcutaneous mass or lump was the most frequent problem in those patients and those masses were associated with inflammatory signs. By the anatomical location of the lesion, some peculiar manifestations could be developed as in orbital, abdominal, urethral, ureteral and vertebral cases. And the lesions could be complicated by haemorrhage or abscess formations. The larval worms hitherto collected in Korea has been identified tentatively as Sparganum mansoni because neither branched larvae nor Sparganum proliferum were ever reported.
parasitology-helminth-trematode ; Spirometra sp. ; sparganum ; case reoprt ; epidemiology

A status survey on Metagonimus yokogawai infection along the Tamjin River basin, South Cholla Do, Korea was conducted from September to November 1977. The snail intermediate host, Semisulcospira sp., the fish host, Plecoglossus altivelis and the inhabitants in three villages in Jangheung and Kangjin Guns were examined for detection of this trematode infection respectively. The results could be summarized as follows: Out of 452 snails, Semisulcospira sp., 105 (23.2%) were found positive for rediae and/or cercariae of M. yokogawai in Jangheung Gun. All of 20 sweetfishes, P. altivelis were infected with metacercariae of M. yokogawai and the mean number per fish was 15,688 and per gram of fish muscle, 234. Out of 606 inhabitants in three villages, 160(26.4%) persons were found infected with M. yokogawai and the mean E.P.G counts per infected cases were 2,078. Sixty cases (9.8%) were positive for ova of Clonorchis sinensis with mean E.P.G., 846, frequently mixed-infected with M. yokogawai. From the above results, it was turned out that the Tamjin River basin is one of the endimic foci of metagonimiasis in Korea. The relatively low infection rate of human host in spite of much higher infection of intermediate hosts were considered to be due to the less population of sweetfishes in the Tamjin River than in the Sumjin River basin.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; epidemiolgy

This study was undertaken to figure out the basic patterns of the frequency distribution of Ascaris lumbricoides in rural Koreans and to find out the effects of changing endemicity on the frequency distribution pattern. Total 853 cases in 6 areas were surveyed from November 1975 to February 1978. The mean ova positive rate was 33.1% and in the range from 23.9 to 66.7% by the surveyed unit. From the analyses of the collected data, the following results were obtained. The overdispersion pattern of worm burden per case was mathematically fitted both to the theoretical values of the negative binomial and Poly-Eggenberger distributions. However, when "0" and lower burden cases were considered, the better fitness was observed in the negative binomial than in Polya-Eggenberger distribution. Although the endemicity of Ascaris is changed, the relative frequency of the lower burden cases is rather constant. The false negative rate of stool examination and unfertilized ova passers in the population were not changed significantly according to the endemicity. And the rate of unfertilized ova passers in infected cases was increased when the endemicity was lowered. From the above results, it is concluded that the overdispersed frequency distribution pattern of Ascaris in an endiemic area is changed by the relatively rapid decrease of heavy burden cases and increase of non-infected cases according to the lowered endemicity due to the impact of the control.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; egg ; epidemiology ; frequency distribution

In Ascaris lumbricoides infection, the faecal examination, undertaking for ova detection, is not always diagnostic. It is just because some of the infected cases has Ascaris worm(s) which do not produce eggs. In the present study, the authors attempted to analyse quantitatively the egg discharging patterns in Ascaris infected cases with low worm burden. The following results were obtained: In 1,861 Ascaris worms collected from 853 cases, the sex ratio was 1: 0.74 (female: male). Sex combinations in each burden of case were always fitted with theoretical values from the binomial distribution; (m+f)(n)= (0.426+0.574)(n). In each worm burden, their sex combination indicated different egg discharging patterns; false negative cases, unfertilized ova passers and fertilized ova passers. When the relative frequency of the above three egg discharging patterns was plotted to worm burden per case, a definite relationship was found. The cases with six or more worms have nil probability to be false negative case or unfertilized ova passer. Out of 853 cases, we found 129 false negative cases. The collected worms from 125 cases were morphologically analysed. It was found that 52% of them were infected with only male worm(s) and 24% were infected with young female worm(s). And in 8.8%, old female(s) with empty uterus were infected. The cause of 15.2% was remained unexplained, even though the collected worms were scrutinized.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; egg ; epidemiology

The efficacy of reduced single doses of mebendazole against Ascaris lumbricoides infection was evaluated by cellophane thick smear and egg counting techinques, in two rural populations from December 1977 to March 1978. Total 191 infected cases were divided into five dose groups; 100 mg single dose, 200 mg single dose, 300 mg single dose, 400 mg and 600 mg in repeated doses. The cure rate of mebendazole in the treatment of Ascaris infection was remarkably high and satisfactory in every dose groups. The egg reduction rates were all over 98 percent in every dose groups. Side effects were observed during the treatment, mainly mild and transient gastrointestinal troubles, and not exacerbated by the increase of doses upto 300 mg in single dose. Above results confirmed that in case of mass chemotherapy of Ascaris infection, 100 mg or 200 mg of single dose treatment is sufficient to achieve the economic and acceptable method of treatment.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; chemotherapy-mebendazole

In order to understand the tissue responses of albino rat host against Paragonimus iloktsuenensis infection, the histopathological changes of the spleen and the lungs in 6 experimental groups of rats were observed in relation with the growth, maturation and migration of this lung fluke. Rats of the experimental groups, each group consisted of 5 rats, were infected with the metacercariae of P. iloktsuenensis which were isolated from brackish water crab, Sesarma dehaani, and were kept for 3 days, 3 weeks, 4 weeks, 7 weeks, 10 weeks and 14 weeks of infection period. Peripheral blood smear slides for the differential leukocyte count were prepared and also worm collection was completed immediately after the infection period. Paraffin sections of the spleen and the lung tissue were stained with hematoxylin-eosin and methyl-green-pyronin (MGP) stain. Those materials from the experimental groups were examined in comparison with the materials obtained from control group, with special reference to immunologic aspects of host response. The results obtained were as follows: The counts of large pyroninophilic cell (LPC) in the periarterial sheath of spleen were rapidly increased in earlier period of infection, and those of peribronchial lymphatic tissue started to increase after the penetration of lungfluke into the lungs. The LPC counts of both the spleen and the lungs were on the decrease in conjunction with the necrosis of the lung fluke in 14th week of infection. On observing differential leukocyte count of peripheral blood smear, the fluctuation of lymphocyte count was proportional to that of LPC count, and the lymphocyte count was consistently higher than that of normal rats. On the other hand, neutrophil count of experimental group showed reciprocal relation to the LPC counts. The nature and characteristics of pulmonary lesion produced by the P. iloktsuenensis were just the same as those produced by P. westermani. The lesions were represented by thick and fibrosclerotic cavern, granuloma due to eggs, pneumonic process and cellular infiltrations.
parasitology-helminth-trematoda ; paragonimiasis ; Paragonimus iloktsuenensis ; histology ; pathology ; lung ; spleen ; granuloma ; pneumonia ; hematoxylin-eosin ; methyl-green-pyronin

A night blood survey was carried out among inhabitants aged over 1 year from the fifteen villages throughout Cheju-Do (Quelpart Island). Blood films from 2,139 persons were examined and 183(8.6 percent) showed microfilariae, the incidences varying according to geographical sources are from 0.8 to 19.5 per cent. All the microfilariae found in this survey were of the nocturnal periodic Brugia malayi. The microfilarial density was 1.9 per cent of blood. The age and sex distributions of microfilaria rate in Cheju-Do were not distinctly different. On the other hand, the intradermal test using Dirofilaria antigen (FPT antigen) and clinical survey of filariasis were also undertaken in same areas of microfilaria survey. Out of 2,449 inhabitants examined 1,434(58.6 percent) persons showed positive reaction of skin test, 503(20.5 percent) persons have clinical manifestations and 112 (4.6 percent) persons showed elephantiasis . It is assumed that Aedes togoi may be the most probable vector of B. malayi in the areas of Cheju-Do.
parasitology ; helminth ; nematoda ; Brugia malayi ; epidemiolgy ; filariasis ; intradermal test ; blood

A histopathological study was carried out on the duodenum of mice and rats experimentally infected by F. seoulensis. Each mouse was infected wit 500 metacercariae and killed after 1, 2, 3 days, 1 and 2 weeks from infection. Each rat was given 1,000 metacercariae and was examined after 1, 2, and 4 weeks from infection. The duodenal tissue sections of mice and rats were stained with hematoxylin and eosin, and PAS stained for the rats of 1 week group. The pathological findings are summarized as below. There were no differences in mucosal findings between the mice and the rats, adn between the location of duodenum, 1 and 5 cm distal to the pylorus. Each worm embraced a villus exclusively with its foliate forebody which was inserted into the intervillous spaces. The fluke pinched villous epithelia using its oral and ventral suckers. The tribocytic organ destroyed the villous epithelia deeply up to the stroma after 3 days from infection. Apparent villous changes were observed in the mice after 3 days from infection. Villous changes were shortening, widening, blunting or fusion. The villous stroma showed edema, microscopic hemorrhage, capillary congestion, dilatation of lymphatics and inflammatory cell infiltration. The cells were lymphocytes, plasma cells, eosinophils and giant cells. Rarely submucosal and transmural inflammation was encountered.
parasitology-helminth-trematoda ; Fibricola seoulensis ; histology ; pathology ; intestine ; rat

A case of sparganosis was presented. The patient was a 43-year-old Korean male who had a history of having eaten raw flesh of snake and frog in Keoje Island during 1950 to 1952 for the purpose of treatment of arthritis by the oriental custom. In the summer, l959, he had slight itching sensation in the left lower scrotal area. A few months later, he noticed the appearance of a peanut-sized mass in that area. However, the mass enlarged gradually to a hen's egg size during two years. On surgical exploration, the mass was found to be a fibro-connective tissue capsule(3 to 4 cm in diameter) in the lower left scrotal area. From the capsule three larvae(l9 to 28 cm by 2 to 6 mm) were freed by dissection without much difficulty. The sources of infection of some formerly reported sparganosis in Korea were discussed. It is most probable that human sparganosis is acquired by ingestion of raw flesh of snake and frog in this country.
parasitology-helminth-cestoda-sparagnum ; sparganosis ; case report