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Korean J Parasitol > Volume 19(1):1981 > Article

Original Article
Korean J Parasitol. 1981 Aug;19(1):18-26. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1981.19.1.18
Copyright © 1981 by The Korean Society for Parasitology
Morphological observation of Enterobius vermicularis expelled by various anthelmintics
Seung-Yull Cho,*Sung-Tae Hong,**Shin-Yong Kang,* and Chul Yong Song
*Department of Parasitology, College of Medicine, Chung-Ang University, Korea.
**Department of Parasitology, College of Medicine, Seoul National University, Korea.
Department of Biology, College of Liberal Arts and Science, Chung-Ang University, Korea.

When enterobiasis cases were treated with anthelmintics only for one time, the interval to recurrence was variable by different drugs used. And this phenomenon is supposedly connected with biological or developmental cycle of the worm and the consequent efficacy of the different anthelmintics. This study was undertaken to confirm this fact by studying the expelled worms morphologically to correlate the anthelmintics efficacy and stage of worm development in Enterobius vermicularis.

A total of 131 children in 3 orphanages was examined by 4 anal swabs (mean positive rate, 80%). They were randomized into 5 experimental groups. Each group was treated with placebo, mebendazole, pyrantel, pyrvinium , and piperazine (70 mg/kg, single dose) respectively. After treatment, all stool were collected for 3 days to get the expelled Enterobius. A total of 6,165 pinworms was studied under the microscope. The sex was discriminated and the length was individually measured.

A number of male pinworms was collected in all groups. Females of 2-11 mm in length were also collected in 5 groups. However, significantly larger number of short females was observed in mebendazole group compared with other groups.

Twenty-one days after the first treatment, all children were again treated with mebendazole. Once more stool were examined. A total of 1,853 worms was collected. In mebendazole group, there were no females longer than 8.74 mm in the second treatment. In pyrvinium group, 8.31mm in lenght was the longest for female. However in control, pyrantel and piperazine groups, females of 2-11 mm in length were collected.

From above results, one could conclude that the removing ability of mebendazole and pyrvinium was satisfactory for the worms in the early stage of development in Enterobius. Pyrantel and single dose of piperazine showed less effective in worm reduction ability especially on those at the early stages.


Fig. 1
The results of anal swab positive rate before and after treatment (↓) in 5 groups.


Table 1
Anal swab positive rates of 4 preliminary examinations by orphanage

Table 2
The rates and consecutiveness of positive anal swabs, the orphanage, sex and age of children in randomized 5 group

Table 3
Total number of collected Enterobius by day in cases followed-up for 3 days

Table 4
The number of pinworms by sex and by length during 3 days of follow-up after mebendazole treatment*

Table 5
Total number and frequency distribution of cases in each category of worm burden of Enterobius in the first treatment

Table 6
The number of Enterobius by sex and by length in each group*

Table 7
Total number of Enterobius collected in each group after the second treatment

Table 8
Number of Enterobius by sex and by length in each group collected in the second treatment*

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6. Hong ST, Cho SY, Seo BS, Yun CK. Chemotherapeutic control of Enterobius vermicularis infection in orphanages. Korean J Parasitol 1980;18(1):37–44.
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