Fifteen-minute consultation: Threadworm in children

Introduction: Enterobiasis (‘threadworm’, ‘pinworm’) is likely the most common parasitic infection, with an estimated 1 billion people infected worldwide.(1) Up to 30% of children globally are affected. (2) The causative parasite is the nematode (roundworm), Enterobius vermicularis, transmitted via the faeco-oral route. Gravid adult females migrate from the gastrointestinal tract to lay eggs on perianal folds, usually at night. The eggs become infectious within 4–6 hours. Infection occurs via autoinfection (transfer of eggs to the mouth through hands that have scratched the perianal area) or from exposure to egg in the environment (ie, bed sheets, clothes). The success of E. vermicularis as a parasite lies in the number of eggs produced by a single female (estimated at around 10 000) (3) and the tenacity of the eggs, which can survive for up to 20 days outside the host and have a strong adherence to fingers and fingernails. (4) There is very little evidence base regarding this ubiquitous parasite, which is often viewed merely as a ‘nuisance’. The most common symptoms are pruritus ani and subsequent irritability due to poor sleep, but, as a 1962 paper vividly puts it: “Other symptoms to which lay people in general attach great value are nose scratching, teeth gnashing, fingernail chewing, nightmares, inattention in school or at home, and agitation”. (5) Infection, particularly when recurrent, can cause significant distress to families, and threadworm infestation is a common clinical scenario for the general practitioner and general paediatrician.