A 5-year-old male came to clinic with a history of constipation and anal itching. The anal itching had been occurring for over 1 month and was worse at night. He would wake his mother because of the itching and scratching. His mother said he had scratches on his bottom that then became so sore that the patient began to retain his bowel movements because of the irritation and soreness. This had been happening for about 2 weeks. “His cousin had pinworms a few months back, so I tried that pinworm medicine from the store, but it didn’t seem to help,” she noted. The past medical history was non-contributory. The pertinent physical exam showed a small but healthy appearing male with normal vital signs and growth parameter in the 10-25%. His perianal area had multiple excoriations. The diagnosis of presumed pinworm infection and secondary constipation was made. Because the cousin and several other extended family members frequently visited the home for extensive time periods, the patient and all the household and extended family members were treated with mebendazole. Hand hygiene and environmental control measures were discussed with the family. The clinical course 3 months later showed that although he was not reinfected, a female cousin had also developed pinworms. Everyone had been retreated and no one else had developed pinworms since.
Pinworm infection is a parasitic infection caused by the roundworm, Enterobius vermicularis. A person is directly infected by fecal-oral transmission of eggs or indirectly such as through contaminated clothing or bedding. It is frequently seen in children and can easily pass to family members especially in crowded conditions. People can become easily reinfected. It is endemic worldwide. Incubation period is usually 1-2 months and eggs can survive outside humans for 2-3 weeks. Humans are the only known reservoir.
Adult worms migrate at night from the anus to the perianal skin and vulvar areas causing anal or vulvar itching. The itching can cause sleep problems and scratching can cause secondary bacterial infection. The worms can exist in alternative locations such as the vagina, Bartholin’s glands and the urethra. Other distant sites such as the appendix have also been cited in the literature.
Diagnosis is by direct visualization of the adult worms about 2-3 hours after sleep or by the “scotch-tape test” where upon wakening the patient has clear cellophane tape applied to the perianal skin. The tape is then reviewed under a microscope to identify the adult worms. See To Learn More below for images of pinworms. In many cases pinworms are treated presumptively because of the difficulty of obtaining specimens.
Treatment for pinworms is by antihelminthic agents such as mebendazole, albendazole, and pyrantel pamoate. Pyrantel pamoate is available over the counter in the US. Medications are given at diagnosis and 2 weeks later because all the eggs may not have been killed with the first dose. In high risk situations, all household or similar members should be treated concurrently. As reinfection is high, subsequent infections are treated the same way.
Hand-washing is imperative for infection control. Hygiene including daily bathing, frequent clothes changing and laundering along with avoidance of long fingernails or nail biting is helpful.
Items to be laundered should not be shaken to decrease the risk of transmitting eggs into the environment and should be placed directly into a washer. Items should be washed in hot water and dried in a hot dryer to kill any eggs. Underclothes and bedlinens should be changed first thing in the morning to decrease the risk of environmental transmission.
Questions for Further Discussion
1. What is the most common parasite in your location?
2. What is the most common helminth in your location?
3. What causes intense pruritis?
- Disease: Pinworms
- Symptom/Presentation: Constipation and Encopresis | Urticaria and Pruritis
- Age: School Ager
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.
Information prescriptions for patients can be found at MedlinePlus for this topic: Pinworms
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Maki AC, Combs B, McClure B, Slack P, Matheson P, Wiesenauer C. Enterobius vermicularis: a cause of acute appendicitis in children. Am Surg. 2012 Dec;78(12):E523-4.
Huh S, Cunha, BA. Pinworm Treatment and Management. Medscape.
Available from the Internet at http://emedicine.medscape.com/article/225652-treatment (rev. 10/26/2012, cited 11/12/13).
Centers for Disease Control. Pinworm (Enterobiasis, Oxyuriasis, Threadworm). Available from the Internet at http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-to-travel/pinworm-enterobiasis-oxyuriasis-threadworm (rev. 8/1/2013, cited 11/12/13).
ACGME Competencies Highlighted by Case
1. When interacting with patients and their families, the health care professional communicates effectively and demonstrates caring and respectful behaviors.
2. Essential and accurate information about the patients’ is gathered.
3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
4. Patient management plans are developed and carried out.
5. Patients and their families are counseled and educated.
8. Health care services aimed at preventing health problems or maintaining health are provided.
10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.
17. A therapeutic and ethically sound relationship with patients is created and sustained.
24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital