When an antipinworm drug was evaluated in human being, the results are still variable according to authors. Among the various factors involved in these variable results, the selection of subjects must be one of them. In the past, in evaluating a drug, the subjects were simply anal swab positive cases in a population. By that kind of selection method, especially in low endemic population, anal swab positives spontaneously turned to egg negatives at random. Moreover, the time, frequency of negative conversion cannot be predicted. By the results, the cure rates obtained from such ill-defined subjects are variable according to the subjected population. Another problem is that evaluation should represent the efficacy in heavily infected cases. To reinforce and overcome such shortcomings, the evaluator shoud select the cases wha are infected with whole developmental stages of worm. And the evaluator should have a method selecting such ideal cases only with anal swabs. To find out such method the results of anal swabs of long-term follow-up without any antipinworm treatment were reevaluated. In 41 children from 6 orphanages of different endemicity, swabs were taken for 8 or 21 times during 36 or 91 days. The positive rate of follow-up swabs was compared with that of already obtained in 4 preliminary swabs. And we collected other data on the combination of 4 anal swab results in different endemicity. The results are as follows: The positive rate of follow-up swabs was significantly different by the consecutiveness of egg positivity in preliminary swabs as well as the endemicity of subjected population. The consecutively positive cases in higher endemicity over 60% showed the highest, and the least variable positive rate in follow-up swabs. The observed frequency of consecutively positive/consecutively negative combination was always higher than the expected one obtained by binomial distribution equation. This indicates that individual hygiene and previous infection are important factors in determining the actual occurrence of subsequent reinfection. Summarizing these results, the subjects for drug evaluation should be those of consecutively positive cases in population over 60% endemicity. These subjects have the lowest chance of spontaneous negative conversion at random period of follow-up swabs. Eligible cases for such criteria would be sufficiently secured in highly endemic population.
parasitology-helminth-nematoda ; Enterobius vermicularis-chemotherapy ; enterobiasis ; epidemiology ; diagnosis

The aim of this study was to estimate the benefit from repeated examinations in the diagnosis of enterobiasis in nursery school groups, and to test the effectiveness of individual-based risk predictions using different methods. A total of 604 children were examined using double, and 96 using triple, anal swab examinations. The questionnaires for parents, structured observations, and interviews with supervisors were used to identify factors of possible infection risk. In order to model the risk of enterobiasis at individual level, a similarity-based machine learning and prediction software Constud was compared with data mining methods in the Statistica 8 Data Miner software package. Prevalence according to a single examination was 22.5%; the increase as a result of double examinations was 8.2%. Single swabs resulted in an estimated prevalence of 20.1% among children examined 3 times; double swabs increased this by 10.1%, and triple swabs by 7.3%. Random forest classification, boosting classification trees, and Constud correctly predicted about 2/3 of the results of the second examination. Constud estimated a mean prevalence of 31.5% in groups. Constud was able to yield the highest overall fit of individual-based predictions while boosting classification tree and random forest models were more effective in recognizing Enterobius positive persons. As a rule, the actual prevalence of enterobiasis is higher than indicated by a single examination. We suggest using either the values of the mean increase in prevalence after double examinations compared to single examinations or group estimations deduced from individual-level modelled risk predictions.
Anal Canal/parasitology ; Animals ; *Diagnostic Tests, Routine/methods ; Enterobiasis/*diagnosis/epidemiology ; Enterobius/*isolation & purification ; Estonia/epidemiology ; Female ; Humans ; Male ; Prevalence ; *Schools, Nursery/statistics & numerical data

In order to determine the status of Enterobius vermicularis infection among schoolchildren in suburban areas of Myanmar, 761 primary schoolchildren in 3 different townships around Yangon City were subjected to a survey using cello-tape anal swabs. The subjected schoolchildren were 383 boys and 378 girls who were 5-7 years of age. Only 1 anal swab was obtained from each child. The overall egg positive rate of E. vermicularis was 47.2% (359 positives), and sex difference was not remarkable (48.6% in boys and 45.8% in girls). However, the positive rate was the highest in South Dagon (54.6%) followed by Hlaing Thayar (43.8%) and North Dagon (34.8%). This difference was highly correlated with the living standards of the people in each township. Nucleotide sequence of the 5S rDNA from the eggs on the cello-tape (2 children) revealed 99.7% identity with that of E. vermicularis reported in GenBank. The results indicated that E. vermicularis infection is highly prevalent among primary schoolchildren around Yangon, Myanmar.
Animals ; Child ; Child, Preschool ; Enterobiasis/diagnosis/*epidemiology/*parasitology ; Enterobius/genetics/*isolation & purification ; Female ; Humans ; Male ; Myanmar/epidemiology ; Parasite Egg Count ; Prevalence ; Students/statistics & numerical data