Pinworm Infection
(Enterobiasis)
A pinworm is the most common roundworm parasite in temperate
climates even in areas with high levels of sanitation. In the
United States, it is the most common of all parasitic roundworm
infections, affecting up to one-third of the country's children.
Because pinworm infection is spread mainly by children, it is found
most often in family groups, day-care centers, schools, and
camps.
Pinworms are small, threadlike roundworms found primarily in the
colon and rectum. The life cycle of the pinworm egg, larva, and
mature worm takes place inside the human body and requires from
three to six weeks to complete.
How do pinworms get into the body?
Pinworms enter the body when eggs are swallowed. The female pinworm
expels thousands of eggs into the environment. Because the eggs are
moist and a bit resistant to drying, they may be able to infect
someone for several days after being distributed in dust. They can
cling to the fingers of children.
Exposure to infective eggs may occur when the person who is
infected scratches the contaminated area (the area around the anus
where the female worm deposits her eggs) and then transfers the
eggs to the fingertips and from there to the mouth. The eggs may be
scattered into the air from bed linen and clothing, and can cling
to doorknobs, furniture, tubs and faucets, and even food. Although
a person may have no symptoms over a long period, episodes of
infection may return repeatedly.
Folklore is filled with fantastic descriptions of symptoms and
abnormal behavior blamed on pinworm infection. Actually, the
symptoms are usually mild and vague. Movement of egg-laden female worms from the
anus will often produce itching of the anus or vagina that, in some
cases, may become very intense and even interfere with
sleep.
