Threadworms
Consultation guide for UK community pharmacy: clinical features, referral criteria, time frame to resolution and management strategy.
Clinical features
- Patients may be asymptomatic but have noticed worms in the perianal area (these are female worms and described as looking like 'threads of cotton')
- Night-time perianal itch is commonly experienced
- Most prevalent in pre-school or school aged children (females more than males) and where people live in close proximity, such as institutions
Referral criteria
- Children under 2 years of age (mebendazole is licensed only for adults and children over 2 years; use below this age is a prescriber decision)
- Treatment failure (can also check compliance with hygiene measures)
- Secondary infection of perianal skin due to scratching (bacterial skin infections may present with clinical features such as weeping, oozing, crusting, pustules, erythema in tandem with systemic symptoms such as fever and malaise)
Time frame to resolution
- Successful treatment using pharmacological measures (mebendazole) normally takes 2 weeks
- If hygiene measures alone are being used, at least 6 weeks are needed to break the cycle
Management strategy
Non-pharmacological advice
- These measures should be used for 14 days from starting treatment with mebendazole. However, if no pharmacological treatment is being used, these measures must be done for 6 weeks to eradicate the threadworms
- Wear close-fitting underpants at night
- Bath or shower (washing around the anus) first thing each morning and use separate towels
- Wash underwear, nightwear and all bed linen daily in a hot wash where possible, being careful not to shake unwashed laundry which could spread the eggs (NHS recommends this particular hygiene point is done daily "for several days after treatment")
- Keep fingernails short and clean; discourage finger sucking and nail biting
- Wash hands and scrub nails thoroughly first thing in the morning, after going to the toilet or after changing nappies, and before eating or preparing food
- Clean the house especially the bedrooms and bathrooms of the house daily by vacuuming the carpets (and mattresses) and damp-dusting the surfaces to remove eggs. Frequently disinfect the toilet seat and handle and ensure the damp-dusting cloth is also regularly washed in hot water
- Place toothbrushes in cupboard and rinse them before use
- It is not necessary to exclude children with threadworms from school
Pharmacological advice
- Mebendazole is suitable for 2 years and over and taken as a single oral dose
- It is prudent to recommend a second dose be taken 14 days after the first given that reinfection is very common and mebendazole has an excellent safety profile
- All household members and close contacts should be treated at the same time
- Pregnancy: advise strict hygiene measures for 6 weeks (the same applies when breast-feeding). Mebendazole is contraindicated in pregnancy in its SmPC (Ovex section 4.3: ‘contra-indicated in pregnancy’), so it must not be sold to a pregnant woman. Any use in pregnancy would be outside the licence and is a decision for the patient's doctor, so refer if treatment is being considered. For breast-feeding, the SmPC advises caution as small amounts are present in breast milk