The most common symptom of pinworms is an itchy rectal area (butt itch). Symptoms are worse at night when the female worms are most active and crawl out of the anus to deposit their eggs.  Although pinworm infections can be annoying, they rarely cause serious health problems and are usually not dangerous. Animals do not harbor pinworms – humans are the only natural host for this parasite. Treatment with routine prescription medications provides an effective cure in almost all cases.  Any individual may develop a case of pinworms, the infection occurs most frequently in school children between 5 to 10 years of age.