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Threadworm

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Enterobius vermicularis, also referred to as pinworm, threadworm or seatworm, is the most common helminthic infection seen in the USA and Western Europe.

  • formerly known as Occiyur vermicularis or oxyurides, this small, white obligate nematode affects 1000 million individuals worldwide (2)
  • affects all people regardless of age, gender or social status
    • 30% of children are infected with the parasite with children between the ages 7 to 11-years most commonly affected
    • female to male infectivity is 3:1
    • commonly seen in temperate climates
    • increased infectivity is seen with overcrowding and poor sanitation (1)

The adult worms reside in the caecum with the female migrating to the anus when ready to lay eggs; this usually occurs at night when they cause pruritus ani.

The eggs are transmitted by the faeco-oral route.

key points re: management (3):

  • 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

Reference:

  1. Powell G, Sarmah P, Sethi B, Ganesan R. Enterobius vermicularis infection of the ovary. BMJ Case Reports. 2013;2013:bcr2013201146
  2. Dunphy L, Clark Z, Raja MH. Enterobius vermicularis (pinworm) infestation in a child presenting with symptoms of acute appendicitis: a wriggly tale! BMJ Case Rep. 2017;2017. pii: bcr-2017-220473.
  3. Public Health England (June 2021). Managing common infections: guidance for primary care

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