Pinworms, or Enterobius vermicularis, are small, thin, white roundworms (about the length of a staple) that sometimes live in the colon and rectum of humans. While an infected person sleeps, female pinworms leave the intestine through the anus and deposit their eggs on the surrounding skin. Pinworm infection is the most common worm infection in the United States.
Good hygiene is important to prevent and control pinworms:
- Because itching and scratching of the anal area is common in pinworm infection, strict observance of good hand hygiene is the most effective means of preventing pinworm infection. This includes:
- Appropriate handwashing (particularly before eating or handling food, after using the toilet, and after changing a diaper)
- Keeping fingernails clean and short
- Avoiding fingernail-biting
- Avoiding scratching the skin in the perianal area
- Daily morning bathing removes a large proportion of eggs; showering may be preferred to avoid possible contamination of bath water. Careful handling and frequent changing of underclothing, night clothes, towels, and bedding can help reduce infection, reinfection, and environmental contamination with pinworm eggs. These items should be laundered in hot water, especially after each treatment of the infected person.
- Control can be difficult in child care centers and schools because the rate of reinfection is high. In institutions, effective prevention and control methods include:
- Appropriate hand hygiene (the most effective method of prevention)
- Mass and simultaneous treatment, repeated in 2 weeks
- Trimming and scrubbing the fingernails and bathing after treatment to help prevent reinfection and spread of pinworms
For more information on pinworm infection, please see CDC’s pinworm fact sheet.