Pinworm is a cosmopolitan parasite with particularly high prevalence in countries with a temperate climate. It has the widest distribution of any parasitic helminth, and it is estimated that approximately 200 million people are infected internationally. The most common helminth infection in the USA and Western Europe, it has become the most common intestinal parasite seen in a primary care setting, regardless of factors such as race, socioeconomic status, and culture. As such, pinworm serves as an exception to the general rule that intestinal parasites are uncommon in affluent societies.In the United States alone, prevalence is estimated to be between 20-40 million, and a CDC surveillance study conducted in 1992 in 35 states found that 11.4% of 9597 tests for pinworm infection were positive. While it is mainly seen in children, pinworm cases have been documented in adults, especially in households where infected children transmit the infection to the rest of the family. Prevalence in children in certain communities has been found to be as high as 61% in India, 50% in England, 39% in Thailand, 37% in Sweden, and 29% in Denmark.