Clinical Overview of Pinworm infection

Prevention

In addition to treatment, strict adherence to proper hand hygiene is the most effective way to prevent pinworm infection and spread. Advise household members and other contacts (school and playmates) to also follow good hygiene practices, including recommendations for bathing and laundering of clothing and bedding.

Control can be difficult in childcare centers, schools, and other facilities because the rate of repeat infections is high. In facilities or institutions, mass and simultaneous treatment, repeated in two weeks, can be effective.

Testing

The most common diagnostic test for pinworm infection is the "tape test". Be prepared to provide collection and storage instructions to patients and caregivers. Emphasize the importance of hand hygiene to prevent further spread.

Healthcare providers generally do not collect other specimens or conduct other tests (e.g., stool samples, urine samples, vaginal swabs, anorectal swabs) because these types of samples usually don't contain enough worms or eggs to easily detect. Occasionally, adult worms may be found incidentally on colonoscopies or in intestinal biopsies. There are no blood tests to diagnose pinworm.

Symptoms

Most people have no symptoms or signs of a pinworm infection. If a person does, it typically itching in the perianal region.

Occasionally, invasion of the female genital tract can occur causing inflammation of the vulva and vagina with rare inflammatory reactions occurring in the pelvis or peritoneum. Appendicitis has been associated with pinworm infection in rare cases.

Treatment and recovery

The medications used for the treatment of pinworm are either mebendazole, pyrantel pamoate, or albendazole. Pyrantel pamoate is available without prescription. Treatment involves two doses of medication with the second dose given two weeks after the first dose. The medications kill worms but cannot kill eggs. The second dose is important to prevent infection by newly hatched adult worms that were not killed by the first treatment because they were still eggs. Health practitioners and parents should weigh the health risks and benefits of these drugs for patients under two years of age.

Oral mebendazole, oral pyrantel pamoate, and oral albendazole are all available for human use in the United States.

The safety of drugs used to treat pinworm have not been studied for pregnant women. If the pinworm infection is compromising the pregnancy (i.e., weight loss, sleeplessness) then treatment can be considered, but it should be withheld until the 3rd trimester when the risk, if any, to the fetus is likely to be reduced. Breastfeeding should not be withheld during mebendazole therapy. Only about 2% – 10% of an oral dose is absorbed, and the amounts of the drug excreted in milk are below the level of detection and appear to be clinically insignificant. Excretion in breast milk of the other drugs used to treat pinworm is not as well characterized.

Care precautions

Mebendazole

Treatment in Pregnancy

Mebendazole is a pregnancy category C drug. Data on the use of mebendazole in pregnant women are limited. The available evidence suggests no difference in congenital anomalies in the children of women treated with mebendazole during mass drug administration (MDA) campaigns compared with those who were not. In MDA campaigns in countries where soil-transmitted helminths are common, World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks and WHO allows use of mebendazole in the 2nd and 3rd trimesters of pregnancy. However, in a pregnant woman infected with a soil-transmitted helminth, balance the risks of treatment for the fetus with the risks of disease progression in the woman in the absence of treatment.

Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) plus there are no controlled studies in women, or studies in women and animals are not available. Prescribe mebendazole only if the potential benefits to the woman justify the potential risks to the fetus.

Treatment during lactation

Mebendazole is minimally excreted in breast milk. WHO classifies mebendazole as compatible with breastfeeding and allows its use in lactating women.

Treatment in pediatric patients

The safety of mebendazole in children is unclear. There are limited data in children under 2 years old. The WHO Model List of Essential Medicines for Children lists mebendazole as an intestinal anthelminthic medicine that can be used for children older than 2 years of age.

Pyrantel Pamoate

Treatment in Pregnancy

Pyrantel pamoate is a pregnancy category C drug. Data on the use of ivermectin in pregnant women are limited. In mass drug administration (MDA) campaigns for which the World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks, WHO allows use of pyrantel pamoate in the 2nd and 3rd trimesters of pregnancy. However, in a pregnant woman infected with a soil-transmitted helminth, balance the risks of treatment for the fetus with the risks of disease progression in the woman the absence of treatment.

Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) plus there are no controlled studies in women, or studies in women and animals are not available. Prescribe pyrantel pamoate only if the potential benefits justify the potential risks to the fetus.

Treatment during lactation

It is not known whether pyrantel pamoate is excreted in breast milk. The WHO classifies pyrantel pamoate as compatible with breastfeeding, although data on the use of pyrantel pamoate during lactation are limited.

Treatment in pediatric patients

The safety of pyrantel pamoate in children is unclear. According to the WHO guidance on preventative chemotherapy, children aged one year and older may use pyrantel during MDA campaigns without diagnosis. The WHO Model List of Essential Medicines for Children lists pyrantel pamoate as an intestinal anthelminthic medicine that can be use in children one year of age and older.

Albendazole

Treatment in Pregnancy

Albendazole is a pregnancy category C drug. There are limited data on the use of albendazole in pregnant women. The available evidence suggests no difference in congenital abnormalities in the children of women accidentally treated with albendazole during mass drug administration (MDA) campaigns compared with those who were not. In MDA campaigns for which the World Health Organization (WHO) has determined that the benefits of treatment outweigh the risks, WHO allows use of albendazole in the 2nd and 3rd trimesters of pregnancy. However, healthcare providers should balance the risks of treatment for the fetus with the risks of disease progression in the woman in the absence of treatment.

Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) plus there are no controlled studies in women, or studies in women and animals are not available. Prescribe albendazole only if the potential benefits to the woman justify the potential risks to the fetus.

Treatment during lactation

Albendazole is minimally excreted in human milk. WHO has concluded that a single oral dose of albendazole can be given to lactating women.

Treatment in pediatric patients

The safety of albendazole in children less than 6 years old is not certain. Studies of the use of albendazole in children as young as one year old suggest that it is safe. According to WHO guidelines for MDA campaigns, children as young as one year of age (able to safely swallow tablets) can take albendazole. These campaigns have treated many children under six years old with albendazole, albeit at a reduced dose.