Background: E. vermicularis infects 300 million people worldwide. Symptomatic and asymptomatic infections can occur in children and adult, there are also very rarely ectopic lesions in female genital tract and in peritoneum. E. vermicularis life cycle is simple, direct, and it is occur in the gastrointestinal lumen, and the infection take place by fecal-oral route following ingestion of embryonated eggs. Re-infection can occur when the patient is reinfected by swallowing eggs via contaminated hands, a retroinfection also may occur when larvae migrate back after hatching into the large intestine. Aim of study: this study is aimed to determine the prevalence of E. vermicularis among pre-school and school age children and study the effect of some scio-economic factors and risk factors that effect on the incidence of it.

Material and methods: This study was applied on 681 children aged less than 10 years from three schools, two kindergartens, and two pediatric hospitals in Thi-Qar province south of Iraq to the period from November 2018 to October 2019. All stool samples (681) were collected from each child early in the morning using stool containers, and diagnosed by light microscope using wet mount preparation for adult pinworms or eggs detection. Socio-demographic status data including gender, age, residence, symptoms, housemates, education, and family income were obtained from the patients or their families. Verbal consents were taken from parents and children for their contribution in this study. Results: The results of this study showed that 53 (7.80%) out of 681 children samples were infected with E. vermicularis included 30 (4.38%) males and 23 (3.37%) females. High prevalence on this infection was found in rural regions 38 (5.58%). The age group 6-8 years was the highest in the infection rate 9 (1.32%), the number of the symptomatic infected children were higher than asymptomatic and constitute 48 (90.56%). The most frequent symptom was anal itching with number 45 (6.6%). The results showed that the pre-school age children were have the higher number of infected housemate 22 (3.23%) compared with the school age, the highest percentage of mothers 22 (3.23%) were had a medium educational degree, and the highest number of mothers 24 (3.52%) had a low knowledge about prevention and control, and the highest number of children 27 (3.96%) were belong to families with medium income level. There was no significance relationship between enterobiasis and gender, month of the year, and family income, while there was a high significance relationship between E. vermicularis infection and places of residence, age groups, presence of some clinical symptoms, mother educational degree, mother’s knowledge about prevention and control against pinworm infection. Conclusion: The present study show a decrease in prevalence of E. vermicularis compared with previous studies in Thi-Qar province. The prevalence was high in rural regions, and higher in school-age children than pre-school age. The highest incidence of infection was among the housemates of pre-school children, and mast mothers of infected children had medium educational degree, and had low knowledge about this infection. Most infected children were belonging to families with medium income level.