To investigate the infection status of Enterobius vermicularis the author tried surveys by scotch-tape anal swap on school-children and household environmental factors considered to have influences on the infection were analyzed by an inquiry method with questionnaire. The survey was carried out in October 1986 and 1988 in urban and suburban areas and the results could summarized as follow: The egg positive rate in anal swab was 16.0 per cent (male 14.5 per cent, female 17.6 per cent) out of 2,156 school-children and higher in female group. The egg positive rate in suburban school-children (17.5 per cent out of 1,305 children of two primary school)was a little higher than that of urban school-children(13.6 per cent out of 851 children of one primary schools). The questionnaire analysis on environmental factors showed some significant relations between the egg positive rate and such factors as the number of brothers and sisters, householder's occupation, and avalibility of childroom or bathroom. The result indicate that, although enterobiasis in school-children has shown decreasing tendency in Korea, it is still considerably high in some urban and suburban areas.
parasitology-helminth-nematoda ; Enterobius vermicularis ; enterobiasis ; epidemiology

Metacercariae were found from 6 samples among 4,382 Parlemon nipponensis which were caught at Podu, Kohung, Korea. The metacercaria was inclined as a larval stage of Paragonimus westermani by following reason: Semisulcospira libertina was the only one species which lives in Podu area. No other metacercaria except Paragonimus westermani were found from the craw or cray fish which were caught in the endemic aera. Metacercariae, ovary, testes and cuticular spines resmbled the characteristics of Paragonimus westermani, which have been described by previous workers.
parasitology ; helminth ; trematoda ; Paragonimus westermani ; metacercaria ; epidemiology

With a purpose to find out natural transition of endemicity of Malayan filariasis in inland Korea, a survey was conducted in June 1980 in Isan-Myeon of Yongpung-Gun (former Yongju-Gun) where an epidemiological investigation had been carried out in 1973 without any control activities such as chemotherapy. Five sample villages were surveyed for microfilaremia by 20 microliter night blood examination among inhabitants and the results of the surveys conducted in 1973 and 1980 were compared to determine natural transition of the endemicity of malayan filariasis during the period of the last 7 years. The current microfilaria rate among inhabitants in the 5 villages was 2.2 percent on the average (male: 1.6 percent, female: 2.8 percent) from 370 persons examined. By village, the rates were 5.9 percent (number of persons examined: 34) in Baranggol, 0 percent (30) in Guitonggl, 4.2 percent (72) in Alseonggol, 0 percent(65) in Jangjagol and 1.8 percent (169) in Saehae. Extremely low microfilaria rate was noted in young age groups. By age group, no positive case was found in those age groups below 30-39 years except 10-14 age group in which 2 positives (4.4 percent) were found. Two positives each were found in the respective age groups of 40-49(3.2 percent), 50-59 (4.4 percent) and over 60 (3.4 percent). In evaluation of the natural transition of the endemicity during the period of the last 7 years, the microfilaria rate turned out from 13.1 percent in 1973 to 2.2 percent in 1980. The difference in the microfilaria rate was 10.9 percent and the natural reduction rate per year was 1.6 percent on the average. From the examination of 35 cases which had revealed microfilaremia 7 years ago, 85.7 percent(30) of them were found to have converted to microfilaria negatives. On the other hand, from the 151 cases which had revealed no microfilaria in 1973, only 0.7 percent (1) of them was found to have converted to microfilaria positive. In the intensity of microfilaremia, the number of microfilaria/20 microliter blood per positive case was 11.0 in 1973 and 9.1 in 1980. The number of microfilaria/20 microliter per examinee was 1.4 in 1973 and 0.2 in 1980, thus reduced to 1/7 during the period of the 7 years. The retarding endemicity of malayan filariasis in inland Korea was considered to be resulted in by the gradual increase of environmental factors in relation to ecology of vector mosquitoes, which adversely affect to the transmission of malayan filariasis. Followings are suggested to be the factors which control the transmission of the malayan filariasis in this area: Inhabitants are the only natural final host of Brugia malayi infection in this area, gradual elevation of living standards of the inhabitants, gradual awakening of consciousness and behavior among inhabitants to protect themselves from mosquito biting using such as mosquito nets and insecticide sprays, preference of animal bait of vector mosquitoes, Anopheles sinensis, increase in number of domestic animals and fowls being raised in the village areas which play a major part of blood donors to vector mosquitoes, and relatively short (3-4 months) period of mosquito season in a year.
parasitology-helminth-nematoda ; Brugia malayi ; epidemiology

From 1960 through 1965, 39 cases with epileptic seizure caused by the Cystricercus cellulosae were experienced at Kaejong Mental Hospital, Okku-Gun, Chollapukdo province. The present study was carried on at the area of Chollapukdo province where Cysticercus cellulosae cases were frequently reported. Thrity-nine Cystricercus cellulosae cases(35 male and 4 female) with epileptic seizure visited Kaejong Mental Hospital . Okku-Gun, Chollapukdo during the years of 1960-1965 from various Gun(county): Okku-Gun 13, Kimje-Gun 7, and Soonchang-Gun 6. The high incidence was found at the age group of 20-49 years and the distribution of 214 subcutaneous nodules were as follows: Trunk 56.6 percent, upper extremities 26.6 percent, head and neck 9.3 percent, lower extremities 7.5 percent. According to the address of above 39 cases, taenia infestation of the inhabitants in the area was examined by questionaire form. Plain rural area (Maryong-Ri, Okku-Gun); Among 803 persons interviewed, 4.0 percent or 32 complained the output of Taenia segments. The male group showed higher incidence (6.4 percent) than the female(1.5 percent) . The highest incidence was observed at the age group of 30-39 years. Most of the inhabitants of the area had the eating habit of raw beef and pork. Mountainous rural area(Bok-Heung-Myun, Soonchang-Gun); Among 542 persons interviewed, 33 or 6.1 percent complained Taenia infection. The higher incidence was observed in the male group(8.7 percent) than in the female group(3.1 percent) , and also at the age group of 20-49 years. They had eating habit of raw beef and pork. The species of adult worm were identified by morphological examination. Totally 36 adult worms(Taenia saginata 21, T. solium 15) were obtained from 26 cases, and it was experienced that 5 T. solium were eliminated from one person.
parasitology-helminth-cestoda ; Taenia solium ; cysticercus ; epidemiology

A total of 860 cellotape anal swab specimens from 326 school children of urban area, 243 of rura1 farm village and 291 of rural fishing village was submitted for Enterobius vermicularis egg detection from September through November 1985. Each specimen was collected in the morning. Among the total 860 children's submitting specimens, 316 (36.7 per cent) were positive for E. vermicularis eggs. Of the 326 children in the urban area, E. vermicularis eggs were detected in the 45 (13.8 per cent). This detection rate was lower significantly as compared with 143 (55.6 per cent) of 243 children in the farm village or 136 (46.7 per cent) of 291 children in the fishing village. The egg detection rate in the male children was lower remarkably than that in the female children.
parasitology-helminth-nematoda ; Enterobius vermicularis ; epidemiology

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

Prevalence study of Metagonimus yokogawai infection, survey of intermediate hosts of Metagonimus yokogawai and food habits of raw sweetfish among inhabitants along Boseong river (120 km), Jeonra Nam Do (province) were carried out. The results are summarized as follows: Among 360 examined, the egg positive case were 128(35.6 percent); male 112(46.7 percent), female 16(13.3 percent). The prevalence rates were different by geographical areas; 42.4 percent in down stream, 49.4 percent in middle stream and 13.3 percent in upper stream. By ages, highest rate, 53.6-59.1 percent was observed among 30-49 group (male 69.6-73.0 percent, female 15.8-35.5 percent). Eggs per gram of feces were 2,084 (200-12,280) in average; down stream 1,708, middle stream 2,590, upper stream l,550. By social strata, the prevalence showed differences; 24.8 percent in primary schoolchildren, 78.4 percent in school teacher and local officers, 30.6 percent in general inhabitants. Clonorchis sinensis infected cases in the areas were 21(5.8 percent) out of 360 examined, and 90.5 percent of them showed mixed infection with Metagonimus yokogawai. Cercariae of Metagonimus yokogawai from the lst intermediate host, Semisulcospira sp., in down and middle streams were detected from 32 snails (5.9 percent) out of 545 examined. All the 22 Plecoglossus altivelis which were caught from the down stream were infected with metacercariae of Metagonimus yokogawai. The number of the metacercariae detected was 22,650 per fish in average, and the number increased from August to October. Experiences of raw sweetfish intake of the inhabitants were found in 208(58.4%) among 356 interviewed by questionaire form (male 76.7 percent, female 20.7 percent). Means of acquisition of the sweetfish were mostly by purchase 68.8 percent, and seasonally in summer. Reason of the raw sweetfish intake was due to the flavor, 83.2 percent. The fish were mixed in soy sause with vinegar before the intake.
parasitology-helminth-trematoda ; Metagonimus yokogawai ; metagonimiasis ; epidemiology

The epidemiological status of ascariasis was analyzed in 8 rural villages in Korea, through observation of its epidemiological parameters such as prevalence, worm burden and basic reproductive rate. Total 978 inhabitants were subjected to stool examination and recovery of worms after chemotherapy with pyrantel pamoate. The results were as follows: The worm positive rate in each village was 16.5-79.5%, while the egg positive rate was 9-18% lower, 3.3-66.7%. The average worm burden(among all inhabitants) ranged from 0.21 to 8.44 by villages and the frequency of cases with each worm burden showed negative binomial distributions with 'k' values of 0.38-0.54. The prevalence rates (worm) in each village was almost identical with the theoretical ones from Anderson and May's equation; p=1-(1+M(*)/k)**(-k), where 'p' is worm prevalence and 'M(*)' equilibrium average worm burden. The basic reproductive rate 'R' was calculated from 1.03 to 2.11. It is suggested that, although 'R' in lower endemic areas is approaching to the breakpoint of reinfection (R=1), control programs of ascariasis in Korea should be continued until it becomes below the level nationwidely.
parasitology-helminth-nematoda ; epidemiology ; Ascaris lumbricoides

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: 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. 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.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; epidemiology ; reinfection

The epidemiological relationship between the current prevalence and monthly reinfection rate of Ascaris lumbricoides was observed in rural communities in Korea by measns of blanket mass chemotherapy and worm collection for measurement of the prevalence and reinfection rates. During the period from 1975 to 1980, a total of 4,466 inhabitants in 10 different localities were treated with 10 mg/kg of pyrantel pamoate and 2 days' whole stools were collected from 2,547 inhabitants. The stools were examined for the presence of expelled adult and/or young worms, which represent the prevalence and reinfection rates for past 2 months respectively. After then, the obtained rates were correlated each other applying the time-prevalence curve proposed by Hayashi. It was observed that the prevalence (overall worm positive rate) and worm burden per individual ranged by areas from 13.6 to 72.3% and 1.4-10.2 respectively. The calculated monthly reinfection rates (X) (from young worm positive rates) according to areas were in the range, 2.6~16.2%, and clearly correlated with the current prevalence (Y) under the equation, Y=1-(1-X)(7.2) where 7.2 is time in month. The equation means that after one time mass chemotherapy the period needed to attain equilibrium of prevalence again would be about 7~8 months. And it is inferred that the majority of reinfected worms in human host turn over every 7~8 months.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; epidemiology ; reinfection