Diagnosis and treatment

Diagnosis is established by early morning application of sellotape to the anus - or moistened swab - with microscopy for typical eggs.

• should be carried out on 3 consecutive mornings right after the infected person wakes up and before he/she does any washing (1)

Treatment of choice in patients aged over two years is with mebendazole. Other possible drugs include pyrantel pamoate, or albendazole (1).

• any of these drugs are given in one dose initially, and then another single dose of the same drug two weeks later
  • the second dose is to prevent re-infection by adult worms that hatch from any eggs not killed by the first treatment (1)
• treatment should be offered to the individual if threadworms have been seen or their eggs have been detected, but all members of the household should be treated simultaneously, even if they have no symptoms
• mebendazole therapy has a 96% cure rate and has the fewest side effects - however, its safety during pregnancy has been questioned
• for patients under 2 years of age, clinicians should weigh the health risks and benefits of these drugs before prescribing (1)
• very little evidence for anthelmintic treatments but it is generally accepted that cure rates with either agent are 90-100% (2)
• retreatment in 1-2 weeks may decrease reinfection rates - this is because the usual medications only kill the adult worms and have no effect on developing eggs or larvae (3)
• other preventative measures may also improve therapeutic success including thorough handwashing and fingernail cleaning, discouragement of thumbsucking, and wearing cotton underwear that has been washed in hot soapy water and is changed twice daily (3)
  
  
• key points (4):
  • treat all household contacts at the same time
  • advise hygiene measures for 2 weeks (hand hygiene; pants at night; morning shower, including perianal area)
  • wash sleepwear, bed linen, and dust and vacuum.
  • child <6 months, add perianal wet wiping or washes 3 hourly
  • child >6 months then treatment with mebendazole
    • 100mg stat; if reinfection occurs, second dose may be needed after 2 weeks (check summary of product characteristics before prescribing)
  • child <6 months or pregnant (at least in first trimester) then only hygiene measures for 6 weeks; mebendazole contraindicated

Education on personal hygiene

• hygiene measures are essential, whether anthelmintic treatment is used or not
• preventative measures may also improve therapeutic success and include the following:
  • thorough handwashing and fingernail cleaning after using the toilet, changing diapers, and before handling food
  • discouragement of thumb sucking, cutting fingernails regularly, and avoiding biting the nails and scratching around the anus
  • spread of pinworm and possible re-infection, people who are infected should bathe every morning to help remove a large amount of the eggs on the skin
    • showering is a better method than taking a bath, because showering avoids potentially contaminating the bath water with pinworm eggs
    • infected people should not co-bathe with others during their time of infection.
  • frequent changing of underclothes and bed linens first thing in the morning
    • avoid shaking these items, carefully place them in washer and should be laundered in hot water followed by a hot dryer to kill any eggs that may be there (1)
  • reinfection rates may be decreased by cleaning floors, bedlinens, and curtains frequently with hot soapy water and cleaning the toilet seat frequently

Treatment of threadworm infection in pregnancy is described in the linked item.

Reference:

1. Centers for Disease Control and Prevention (CDC) 2013. Parasites - Enterobiasis (also known as Pinworm Infection)
2. Prescribers' Journal (1998), 38(2), 80-6.
3. Shoup B.Diagnosis and management of pinworm infection. Primary Care Update for Ob/Gyns 2001;8 (6): 240-243.
4. Public Health England (June 2021). Managing common infections: guidance for primary care