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Korean J Parasitol > Volume 17(2):1979 > Article

Original Article
Korean J Parasitol. 1979 Dec;17(2):98-104. English.
Published online Mar 20, 1994.  http://dx.doi.org/10.3347/kjp.1979.17.2.98
Copyright © 1979 by The Korean Society for Parasitology
Egg discharging patterns of Ascaris lumbricoides in low worm burden cases
Byong-Seol Seo,Seung-Yull Cho and Jong-Yil Chai
Department of Parasitology and Institute of Endemic Diseases, College of Medicine, Seoul National University, Korea.

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:

1. 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.

2. 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.

3. 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.


Fig. 1
The probability of stool examination results according to the worm burden per case.


Table 1
Sex ratio of collected Ascaris lumbricoides by surveyed area

Table 2
Sex combination of A. lumbricoides in low worm burden cases

Table 3
Relationship between sex or sex combination of infected Ascaris worms and the result of stool examination for eggs

Table 4
Analysis of the false negative results in stool examination by observation of the collected worms from each case

1. Cho SY. Study on the quantitative evaluation of reinfection of Ascaris lumbricoides. Korean J Parasitol 1977;15(1):17–29.
2. Fushimi J. Jpn J Parasit 1959;8(1):108–114.
3. Fushimi J. Jpn J Parasit 1959;8(2):116–173.
4. Morishita K. Progress of Medical Parasitology in Japan 1972;4:1–153.
5. Seo BS, Cho SY, Chai JY. Frequency Distribution Of Ascaris Lumbricoides In Rural Koreans With Special Reference On The Effect Of Changing Endemicity. Korean J Parasitol 1979;17(2):105–113.
6. Yokogawa S, et al. J Med Assoc Formosa 1932;31:552–570.
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