According to the Centers for Disease Control, pinworms account for the most common parasitic infection caused by worms, infecting around 40 million people in the United States. Pinworms affect primarily preschool- and school-aged children, although institutionalized people and their caretakers are also at risk. There are many myths and misconceptions about how pinworms are spread, the most common being that humans can get pinworms from the family pet or another animal.
The formal name for the parasite that causes human pinworm infections is Enterobius vermicularis, a type of roundworm. But informally, pinworms have also been called threadworms and seatworms. According to the CDC, humans are considered to be the sole host for pinworms, and infections are spread from one infected person to another.
How Pinworms Spread
According to the CDC, pinworms are spread through the fecal-oral route. You can get pinworms if you drink or eat something that is contaminated with the worm's eggs, or if you touch a contaminated object. A typical scenario in which pinworms are spread from children to other family members is when the pinworm-infected child scratches his anus with his hands and then touches something else, such as a toy, countertop or bedding, depositing eggs on these surfaces. You then touch one of these things with your own hands and put them to your mouth. Pinworm eggs can survive for two to three weeks on hard and soft surfaces, says the Mayo Clinic. If they linger in bedding or curtains, you can inhale them as you sleep and subsequently ingest them. Someone can continuously reinfect herself with pinworms if she scratches her anus and then puts her fingers to her mouth.
The most common symptom that points to a pinworm infection is an extremely itchy bottom. Often, you can see the female pinworms moving around the rectum first thing in the morning before you have defecated (signs of pinworms are harder to detect after a bowel movement, shower or bath). Sometimes you can see them moving around in underwear and bedding. Pinworms cause more discomfort than they do serious medical complications. However, sometimes pinworm infections may lead to weight loss, urinary tract infection, infection of the peritoneal cavity (in females), and sometimes a Sientamoeba fragilis infection caused by a parasite sometimes present in pinworm eggs.
Do Pets Spread Pinworms?
The family dog or cat can't give you or your child pinworms, as he is not a host for this parasite. Pet cats get other types worms, but if you notice your pet exhibiting anal itching or note the presence of wormlike segments on his anus, it's most likely a tapeworm--which is another type of worm entirely.
Pinworms and their eggs can be killed with prescription medications that may include albendazole or pyrantel; sometimes more than one dose is needed for treatment to be effective. Because pinworms are highly contagious, your doctor will probably recommend that everyone in the family receive treatment at the same time. Preventing reinfestation is extremely important, as well. Launder clothing, bedding and towels, and scrub hard surfaces well. Counsel children on the importance of not scratching their bottoms and then putting their fingers to their mouths or touching other objects. Frequent hand washing is necessary. Because pinworm eggs can reside under the fingernails, keeping nails clipped short is another way to prevent reinfestation from occurring.