Pinworm infestation common among children

Dear Dr. Donya,

My son is 20 months old now. One night I noticed him scratching his bottom and this happened again the next day. So I gave him a teaspoon of antiworm syrup. The next morning there were many worms in his excrement.

Is this normally experienced by an infant under two years old? Considering that he never plays on exposed ground and always eats well-cooked dishes, should I continue giving him medicine? Please also advise on the correct time and dosage.

-- Kim C.

Dear Kim,

Itching of the skin around the anal area may have many causes. In children, a common cause is infestation with the parasite that causes pinworms. Pinworm (Enterobius vermicularis) infestation is a common occurrence in families with children. The pinworm lives in the lower intestine. At night, the female worm migrates out through the anus, lays large numbers of eggs, and dies. After a few hours, the eggs can spread to other individuals or reinfect the host if they are transferred to the mouth by contaminated food, drinks or hands. After the eggs are swallowed, they hatch in the small intestine and migrate down to the lower intestine. The entire cycle takes three to four weeks and eggs are viable for up to two to three weeks.

Humans are the only hosts for the infection -- dogs and cats do not harbor or transmit pinworms. The infection can be spread by airborne eggs, once a diagnosis is made, the person should be treated and bedding and underwear should be laundered using hot water and a mild bleach solution.

Care in the bathroom and kitchen areas and good hand washing are the means of prevention. Affected people should avoid scratching and should take special care to keep their fingernails clean, to wash their hands after defecating and to wash the bedding to help prevent the spread or recurrence of the infection.

Pinworms can be annoying, but not serious. The infestation is easily treated with a medicine called mebendazole, typically a single dose treatment given to everybody in the house. Good personal hygiene with emphasis on washing hands after using the bathroom is mandatory. Children should be taught not to put their hands or place other objects in their mouth.

-- Dr. Donya