Relationships between the results of repeated anal swab examinations and worm burden of Enterobius vermicularis.

To relate the results of repeatedly undertaken anal swabs to worm burden of Enterobius vermicularis in a highly endemic community, 193 rural schoolchildren, divided into 4 groups, were examined daily by Scotch-tape anal swab method, 1, 2, 3 and 4 times respectively. All of the schoolchildren were treated with pyrantel pamoate 10 mg/kg body weight exactly after the last anal swab in each group disregard the results. And all of the expelled E. vermicularis were collected and counted. It was found that 68.8% of total anal swabs were positive and the collection rate of E. vermicularis was 90.7% with average worm burden, 17.0, in surveyed children. From the analyses of the obtained data, following three inferences were derived. 1. The consecutive postive findings of anal swabs could not reduce the possibilities of detecting light worm burden cases when the anal swabs were undertaken daily up to 4 times. 2. The possibilities of detecting the heavy infection cases were found in consecutively positive categories of anal swab and the presence of negative result(s) of anal swab during the consecutive examinations did denote the reduced possibilities of detection heavy infection. 3. The consecutive negative findings in anal swab have tendenicies reducing the possibilities of detecting heavy worm burden cases. Above results were highly suggestive that the processes of infection loss in E. vermicularis were taken place continuously, allowing daily small allotments of discharge of fully gravid worms in heavy infection cases and massive discharge in a very short period of time is practically rare event.