Pinworm (threadworm) infection

Notification requirement for pinworm (threadworm) infection

Notification is not required.

Primary school and children's services centres exclusion for pinworm (threadworm) infection

Exclusion is not required.

Infectious agent of pinworm (threadworm) infection

Enterobius vermicularis is an intestinal nematode.

Identification of pinworm (threadworm) infection

Clinical features

In the majority of children and adults, infection is asymptomatic. The migration of the female worm from the rectum and then the anus to lay eggs on the perianal skin during the night can lead to perianal pruritus or disturbed sleep or irritability. Sometimes, secondary infection of the scratched skin occurs. In children, the pinworm can cause vulvovaginitis during its migration from the anus.

Pinworms or their eggs have occasionally been detected at other sites, such as the liver and lung. Rarer clinical manifestations include salpingitis, pelvic pain and the formation of granulomas in the peritoneal cavity.

Diagnosis

The diagnosis should be suspected in children with a perianal itch, and is confirmed by detection of the pinworms’ characteristic eggs. Applying clear sticky tape to the perianal skin and examining it for eggs is the best way to make the diagnosis. This is best done in the morning before bathing, as the worms migrate during resting periods. Microscopy on faeces can be conducted, although finding eggs is exceptional.

Incubation period of pinworm (threadworm)

The lifecycle requires 2–6 weeks to complete. The eggs are fully embryonated and are infective within a few hours of being deposited. Male and female pinworms vary in size, ranging between 2 mm and 13 mm in length and up to 0.5 mm wide, and are yellowish white. A long, thin and sharply pointed tail distinguishes the female worm.

Public health significance and occurrence of pinworm (threadworm) infection

The pinworm is the most common helminth parasite of temperate regions. These infections are found worldwide and affect all socioeconomic groups.

Less attention is paid to the pinworm in tropical regions, presumably because of the prevalence of more important parasites. Pinworm infections predominantly affect paediatric populations, in which the prevalence is reported to be 10–50 per cent in some groups.

Reservoir of pinworm (threadworm)

Humans are the only reservoir. Pinworms of other animals are not transmissible to humans.

Mode of transmission of pinworm (threadworm)

Pinworms are transmitted by direct transfer of infected eggs by hand from the anus to the mouth of the same or another person. They can also be transmitted indirectly through bedding, clothing, food or other articles. Spread is facilitated by overcrowding.

Period of communicability of pinworm (threadworm) infection

Communicability continues as long as the eggs are being discharged onto the perianal area. The eggs can survive for several days in the right conditions. Reinfection from contaminated hands is common.

Susceptibility and resistance to pinworm (threadworm) infection

Infection does not confer immunity.

Control measures for pinworm (threadworm) infection

Preventive measures

Preventive measures include:

• effective handwashing, particularly before eating or preparing food.
• keeping nails short
• discouraging scratching of the bare anal area and nail biting
• bathing or showering daily
• changing to clean underwear, nightclothes and bedsheets frequently, preferably after bathing.

Control of case

There are a number of drugs available for treatment, including pyrantel embonate, mebendazole and albendazole. Consult the current version of Therapeutic guidelines: antibiotic.

Care should be taken to change the linen and underwear of the infected person daily for several days after treatment, taking care to avoid dispersing the eggs into the air.

Control of contacts

Not applicable.

Special settings

Public health education on the importance of handwashing may assist.

Outbreak measures for pinworm (threadworm) infection

Not applicable.