What is the treatment for a human infected with Enterobius vermicularis (pinworms) from a puppy, presenting with anal pruritus (itching)?

Treatment for Pinworm (Enterobius vermicularis) Infection in Humans

The treatment of choice for human pinworm infection presenting with anal itching is albendazole 400 mg or mebendazole 100 mg as a single oral dose, with a repeat dose after 2 weeks to eradicate any newly hatched worms. 1, 2

Diagnosis

• The "sellotape test" (cellophane tape test) is the preferred diagnostic method for pinworm infection, performed by placing adhesive tape on the perianal skin in the morning before bathing or defecation to collect eggs 1, 3
• Stool examination has poor sensitivity for pinworm detection as eggs and adult worms are not typically passed in stool 3
• Nocturnal perianal itching is the most common symptom of pinworm infection 2, 3
• Other symptoms may include weight loss, irritability, diarrhea, abdominal pain, and occasionally colitis with eosinophilia 1, 3

Medication Options

• First-line treatment options (equally effective):
  • Albendazole 400 mg as a single oral dose 1, 2
  • Mebendazole 100 mg as a single oral dose 1, 4
• Both medications should be repeated after 2 weeks to kill newly hatched worms and prevent reinfection 2, 5
• Mebendazole has demonstrated cure rates of approximately 95% for pinworm infections 4
• For pregnant women, pyrantel pamoate is preferred over mebendazole and albendazole due to safety concerns 5

Treatment of Household Members

• Treatment of all household members should be considered, especially if there are multiple or repeated symptomatic infections 4, 5
• Reinfection is common even with effective medication due to the high contagiousness of pinworms 4, 5

Prevention of Reinfection

• Wash hands and fingernails with soap frequently, especially before eating and after using the toilet 4
• Wear tight underwear both day and night and change them daily 4
• Clean bedroom floors by vacuuming or damp mopping for several days after treatment 4
• Wash bed linens and night clothes after treatment 4
• Keep toilet seats clean 4
• Clip fingernails short to reduce egg collection under nails 5
• Avoid finger-sucking, nail-biting, and scratching in the anogenital area 5

Management of Anal Itching

• For symptomatic relief of anal itching, topical anti-itch preparations may be used alongside oral anthelmintic treatment 6
• Options include cooling agents, local anesthetics, or mild topical corticosteroids for short-term use 6

Special Considerations

• Pinworm infections can occasionally mimic appendicitis or other abdominal conditions 7, 8
• Eosinophilia may be present in some cases, particularly with heavy infections 1, 3
• In females, pinworms may colonize the genital tract, causing vaginal discharge 1, 3

Treatment Algorithm

1. Confirm diagnosis with sellotape test if possible (but can treat empirically based on classic symptoms)
2. Administer single dose of albendazole 400 mg OR mebendazole 100 mg
3. Treat all household members simultaneously
4. Implement hygiene measures to prevent reinfection
5. Repeat treatment in 2 weeks
6. Consider symptomatic treatment for anal itching if needed

Human pinworm infections are highly contagious but respond well to appropriate treatment when combined with preventive measures to avoid reinfection 4, 5.