Figure 2-1. Whipworms.
c. Enterobius vermicularis (pronounced EN-tur-O-bee-us ver-mick-yoo-LAIR-
is). Enterobius vermicularis is frequently referred to as the pinworm (see figure 2-2).
This roundworm is small; females are usually 8 to 13 mm long and males are usually 1
to 5 mm in length. Humans are the only known host of pinworms. After the host ingests
the pinworm eggs, the eggs hatch in the small intestine. The worms then develop and
begin the reproductive cycle. The females leave the large intestine to deposit their eggs
(up to 11, 000) in the perianal area of the human body. Pinworms usually live in the
intestines, but they can travel to the stomach, esophagus, and nose. Pinworm
infestations are common, especially in children. Since the eggs are not usually laid in
the intestine, stool examinations for purposes of worm identification are usually
ineffective. A piece of clear cellophane tape with the sticky side applied around the
anus in the morning before the patient has washed or defecated, can be used to gather
samples for the physician to examine for positive identification of the pinworms.
Although pinworm infestations are usually self-limiting and not harmful to the patient,
they produce some signs and symptoms of disease. These signs and symptoms
include mild nausea or vomiting, loss of sleep, irritability, severe itching around the anus
(important because the eggs can get on the hands during scratching and be ingested
Figure 2-2. Pinworm.