The cause of pinworm infection is inadequate hygiene. Eggs are transferred from the anus of an infected person to either their own mouth, re-infecting themselves, or another surface. If somebody else touches that contaminated surface and then touches their mouth, they may have ingested the eggs and can become infected.

How does a person get pinworms?

People become infected, usually unknowingly, by swallowing (ingesting) infective pinworm eggs that are on fingers, under fingernails, or on clothing, bedding, and other contaminated objects and surfaces. Because of their small size, pinworm eggs sometimes can become airborne and ingested while breathing.

Where do pinworms come from originally?

Pinworm findings in archaeological material outside the New World have been scarce for unknown reasons, and it is hypothesized that this parasite did not originate in the Americas, but rather arrived via land route through the Beringia.