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

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

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

In the present study, the effect of primary infection to reinfection with Ascaris suum larvae was experimented in mouse model. Mice were challenged with l,000 infective stage eggs of Ascaris suum. The embryonated eggs were directly introduced into stomach of mice. Reinfection was performed at 50 days after the primary infection with same method as primary infection. Mice were sacrificed 3, 5, 7, 10, 15 and 20 days after infection in both groups respectively. Larvae collected from livers and lungs with Baermann's apparatus were enumerated and measured after sacrifice. Sera of mice were also collected at same time. The results of the experiment were as follows: With antigen prepared from coelomic fluid of adult Ascaris suum and sera collected from mice before reinfection, the production of antibody in experimental mice was confirmed by the gel-diffusion technique. In the livers of reinfected mice, the larvae were recovered up to 10 days after challenge, otherwhile in the primary infected mice, the larvae were observed up to 7 days. The maximum number of larvae were observed in the lungs of primary infected mice on 10 days after inoculation. In the lungs of reinfected mice, maximum number of larvae were recovered on 7 days after, only few larvae were recovered on 10 days after reinfection. As regards the growth of the larvae, the third stage larvae, over 500 micrometer in length, appeared in livers at 5 days after reinfection, but it couldn't be found on 7 days and 10 days after challenge. The third stage larvae continuously developed were observed in lungs of mice from 5 days after reinfection. In conclusion, it was found that development of larvae in livers of immune mice were probably repressed by the immune mechanisms being rised in livers and defence mechanism is also acting by interfering with the process of larval penetration into the lung from the liver.
parasitology-helminth-nematoda ; immunology ; Ascaris lumbricoides ; mouse

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

For the purpose of making a comparative study of protein compositions in Ascaris suum by sexes and body parts, extracts were prepared from whole bodies, body walls, genital organs, digestive organs and body fluid, of both sexes. And electrophoretic analysis was conducted using polyacrylamide slab gel in the presence of sodium dodecyl sulfate. The results were as follows: In this study, protein bands of each part were separated in the largest number and most clearly under 8 -12 percent (10 percent) gradient gel condition. The number of bands by body parts was 43 in body walls, 51 in genital organs, 47 in digestive organs, and 34 in body fluid. When examined in terms of sex, the number of bands of whole body was 38 in females and 35 in males. The electrophoretic patterns of body wall protein were in most cases similar with those seen in digestive organs. And the band with a molecular weight of 72,900 was unique to the body wall, and the 122,000 MW band was unique to the female body wall. In genital organ extracts, large molecular weight proteins (more than 80,000) were more frequently met. The molecular weights showed some differences between the two sexes. Of the bands, those having molecular weights of 119,700, 100,500, 88,500 and 86,100 were unique to the female genital organs. On the other hand, the male genital organs showed unique bands having molecular weights of 87,100, 82,800, and 15,500. An unique band common to the genital organs of both sexes was one having 49,300 MW. In the digestive organs evenly distributed protein bands of molecular weights of l0,000-120,000 were observed. The band having 59,800 MW was unique to the digestive organs. The number of bands obtained from body fluid was comparatively small, and the number of bands having less than 30,000 MW was 7, accounting for 55 percent of the total protein amounts. The bands having 47,600 MW and 31,400 MW were unique to body fluid.
parasitology-helminth-nematoda ; Ascaris suum ; biochemistry ; protein

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

The present study was undertaken to determine whether an analysis of the collected worms after chemotherapy with pyrantel pamoate could be used as a method measuring the amount of reinfection of Ascaris lumbricoides in a given population. A total of 398 cases from two villages and one primary school were treated with pyrantel pamoate with dose of 10 mg/kg of body weight. The whole two-day stool specimens after treatment were examined. Out of 279 followed cases, 110 cases (39.4%) were found infected with A. lumbricoides. A total of 527 worms were collected, they were in the range of 1.2 to 32.5 cm in length and 0.0004 to 7.424 gm in weight. The measurements were made on the specimens fixed with 10% formalin. The relationship between the number of worms per positive case(X) and the total weight of worms(Y) showed the positive linear regression; this was expressed by the equation, Y= 2.012X + 1.135 (Sy=4.84, r=0.92). From the above results, it seems that worms of small size may not be considered as a product of crowding effect in heavy infections. The relation between the weight(Y) and length(X) of collected A. lumbricoides was expressed as an equation, Log(e)Y=3.032 log(e)X-8.2903(S.E. of reg. coeff.= 0.040, r=0.957). In the intestinal phase of development, the first increase of the length of the worm, up to 10-12 cm was observed and this followed by the well marked increase of weight from 13 cm upto 32.5 cm in the sexually maturing phase. A total of 285 schoolchildren were treated by pyrantel pamoate, 10 mg/kg of body weight three times each in two months interval. After the second and third treatment, thirteen and fifty-four worms were collected respectively. They were measured in length and weight and were all in the range of 1.2 to 13.2 cm in length and 0.0006 to 0.436 gm in weight except 3 fully matured adults. It is assumed that these young worms, defined as those less than 0.5 gm in weight and less than 13 cm in length should be regarded as those having reinfected during the previous two months period. From this observation, it was possible to calculate the reinfected number of young worms. Therefore, it is suggested that the average number of Ascaris per month per person means the reinfection amount in a certain period of time in an endemic area of A. lumbricoides. In other words, reinfection amount may be expressed by the calculated figure of young worms reinfected in a certain period of time in a population.
parasitology-helminth-nematoda ; Ascaris lumbricoides ; ascariasis ; epidemiology-reinfection ; pyrantel pamoate

This study was conducted to determine the effect of oxantel/pyrantel tablets, oxantel suspension, pyrantel dry syrup and pyrantel tablets against T. trichiurus and A. lumbricoides infections. Twenty-four cases of mixed infections of T. trichiurus and A. lumbricoides were treated with oxantel/pyrantel tablets at a single dose of 20 mg/kg of body weight, and 49 cases of single infection of T. trichiurus were administered oxantel suspension at a single dose of 15 mg/kg of body weight. On the other hand, single infection of A. lumbricoides in 18 cases was administered pyrantel dry syrup at a single dose of 5 mg/kg of body weight. In the above 91 cases, the negative conversion rate and the egg reduction rate of egg out-put before and after the drug administration were examined by the cellophane thick smear method and Stoll's egg counting technique. A follow-up examination was carried out 3-4 weeks after the drug administration. Other 59 cases of single and mixed infection of T. trichiurus and A. lumbricoides were examined by the cellophane thick smear method only and administered pyrantel tablets at a single dose of 2.5 mg/kg of body weight. The results were summarized as follows: The prevalence rates of T. trichiurus and A. lumbricoides infection in this study were 42.8% and 27.2% respectively by the cellophane thick smear method among 1,066 stool specimens. The egg negative conversion rate and the egg reduction rate in the administration of oxantel/pyrantel tablets at a single dose of 20 mg/kg body weight were 75.0% and 97.8% respectively in T. trichiurus infection and 100% each in A. lumbricoides. The egg negative conversion rate and the egg reduction rate in the administration of oxantel suspension at a single dose of 15 mg/kg body weight were 85.7% and 93.0% respectively in sinlge infection of T. trichiurus. The egg negative conversion rate and the egg reduction rate in the administration of pyrantel dry syrup at a single dose of 5 mg/kg body weight were 100% each in single infection of A. lumbricoides. The qualitative evaluation in cases of single and mixed infection of T. trichiurus and A. lumbricoides were by means of pyrantel tablets at a single dose of 2.5 mg/kg body weight, the cure being 100% against A. lumbricoides but 17.0% against T. trichiurus. There were no undesirable side effects in this study and oxantel suspension and pyrantel dry syrup were well accepted and tolerated.
parasitology-helminth-nematoda ; Trichuris trichiurus ; Ascaris lumbricoides ; chemotherapy ; oxantel ; pyrantel