How to treat a 25-year-old male with enterobiasis (infection with intestinal parasites) presenting with worms in the anus for 15 years?

Treatment of Chronic Enterobiasis (Pinworm Infection)

This 25-year-old male with 15 years of recurrent pinworm infection should be treated with albendazole 400 mg orally as a single dose, with mandatory simultaneous treatment of all household contacts, followed by a repeat dose after 2 weeks to eliminate any newly hatched larvae. 1, 2

Initial Diagnostic Confirmation

• Obtain perianal adhesive tape test (cellophane tape test) in the morning before bathing to visualize eggs microscopically, as this is more sensitive than stool examination for enterobiasis 3
• Concentrated stool microscopy has lower sensitivity for pinworms compared to the tape test 3
• The 15-year history suggests either chronic reinfection from environmental contamination or untreated household contacts serving as reservoirs 2, 4

First-Line Pharmacologic Treatment

Albendazole 400 mg orally as a single dose is the recommended first-line treatment 1, 3

Alternative options if albendazole is unavailable:

• Mebendazole 100 mg orally as a single dose (cure rate 95% for pinworm) 2, 4
• Pyrantel pamoate is another effective alternative 4

Critical Treatment Strategy for Chronic Cases

All household members and close contacts must be treated simultaneously, regardless of symptoms, because pinworms are highly contagious and asymptomatic carriers perpetuate transmission 1, 2

Mandatory repeat dosing after 2 weeks is essential to eliminate parasites that were in the egg stage during initial treatment, as anthelmintics only kill adult worms 2, 5

Environmental Decontamination Measures

The chronic 15-year duration indicates failure of previous hygiene measures. Implement these interventions concurrently with medication:

• Wash all bed linens, nightclothes, and underwear in hot water on the day of treatment without shaking them (to avoid aerosolizing eggs) 2
• Vacuum or damp-mop bedroom floors daily for several days after treatment—avoid dry sweeping that disperses eggs into the air 2
• Wear tight-fitting underwear day and night, changing daily to prevent nocturnal egg deposition and auto-reinfection 2
• Rigorous hand hygiene with soap before eating and after toilet use, with attention to cleaning under fingernails where eggs accumulate 2, 1

Common Pitfalls Leading to Treatment Failure

The 15-year chronicity suggests these errors have occurred repeatedly:

• Failure to treat household contacts simultaneously is the most common cause of reinfection 1, 2
• Omitting the 2-week repeat dose allows newly hatched worms to mature and restart the cycle 2, 5
• Inadequate environmental cleaning leaves viable eggs (which survive up to 3 weeks) on surfaces and in dust 2
• Scratching behavior perpetuates auto-reinfection through the fecal-oral route 2

Monitoring and Follow-Up

• Clinical improvement should occur within days, with resolution of perianal itching and visible worms 4
• Repeat tape test 1 week after the second dose to confirm eradication 5
• If symptoms persist despite two treatment cycles with proper hygiene, consider:
  • Non-compliance with environmental measures 2
  • Untreated household contacts continuing transmission 1
  • Rare ectopic enterobiasis (though this typically presents with different symptoms like pelvic pain in females) 6, 7

Special Considerations

• Screen for psychological impact: Chronic parasitic infection, especially in overcrowded conditions, can cause insomnia, irritability, and anxiety that may be mistaken for primary psychiatric conditions 8
• Evaluate living conditions: The 15-year duration raises concern about overcrowding, poor sanitation, or institutional settings (schools, dormitories) that facilitate ongoing transmission 4, 8
• Mebendazole is contraindicated in pregnancy; pregnant household contacts should defer treatment or use alternative strategies 2