Infestation with threadworms (Enterobius vermicularis, sometimes called pinworms) is extremely common amongst children in the UK. Infestation occurs after swallowing eggs that are present in the environment.


  • Incidence: 800.00 cases per 100,000 person-years
  • Peak incidence: 6-15 years
  • Sex ratio: 1:1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Clinical features

Threadworm infestation is asymptomatic in around 90% of cases, possible features include:
  • perianal itching, particularly at night
  • girls may have vulval symptoms


Diagnosis may be made by the applying Sellotape to the perianal area and sending it to the laboratory for microscopy to see the eggs. However, most patients are treated empirically and this approach is supported in the CKS guidelines.


  • CKS recommend a combination of anthelmintic with hygiene measures for all members of the household
  • mebendazole is used first-line for children > 6 months old. A single dose is given unless infestation persists