Number of intrauterine eggs in female Enterobius vermicularis by body length

ABSTRACT

In order to correlate the number of eggs in female Enterobius vermicularis with their body length and to re-evaluate the number of eggs liberated by gravid females, a total of 203 worms were examined. Those females were removed from naturally infected orphans with mebendazole (100 mg) and had been fixed in 10 percent formalin(Cho et al., 1981). The decent ones which were selected under dissecting microscope were unbroken, neatly fixed females without contaminated eggs on their surface. The worms were measured by their body length, softened in 0.1N NaOH solution overnight, and teased by dissecting needles. And their number of shelled eggs was measured in a counting chamber made as described by Denham et al. (1971). The results were summarized as follows The observed females, 4.10-9.90 mm long, began to have shelled eggs in uterus when body length was 5.50 mm or longer. The percentage of females with eggs in uterus was as follows by range of body length 25 percent in 5.50-5.99 mm long, 53.3 percent in 6.00-6.49 mm long, 86.7 percent in 6.50-6.99 mm long, 95.2 percent in 7.00-7.49 mm long and 100 percent in 7.50 mm or longer. The mean and standard deviation of egg number were as follows by the length of females 19+/-50 in 5.50-5.99 mm long, 734+/-1,597 in 6.00-6.49 mm long, 1,473+/-1,606 in 6.50-6.99 mm long, 1,530+/-2,055 in 7.00-7.49 mm long, 2,567+/-2,046 in 7.50-7.99 mm long, 5,598+/-2,470 in 8.00-8.49 mm long, 9,318-2,651 in 8.50-8.99 mm long, 10,678+/-2,892 in 9.00-9.49 mm long and 13,323+/- 1,778 in 9.50-9.90 mm long. The numbers of uterine eggs showed greater individual variation when the female lengths were in range of 5.5-8.0 mm. When the female length was longer than 9.0 mm, the egg numbers were over 10,000 in majority, and showed lesser individual variations. Above results suggested that the egg production in female E. vermicularis began in 28-32 days after infection and that in early stages, the egg production varied by individual worms, but in gravid females longer than 9.0 mm at last deposited 10,000 to 16,000 eggs in their uterus with the least individual variations.