Threadworm (Enterobius vermicularis)

Mebendazole oral 100 mg for 1 dose; if re-infection occurs, a second dose may be needed after 2 weeks

Threadworm infection most commonly presents with intractable peri-anal itch, especially during the night and the early morning, but infection can also be asymptomatic.

Treat all members of the household at the same time even if asymptomatic (unless treatment is contraindicated). Treatment with an anthelmintic is contraindicated in women in the first trimester of pregnancy. Women in the second or third trimester and women who are breastfeeding may prefer not to take an anthelmintic and use hygiene methods. If there are frequent recurrences consider seeking advice from a consultant in infectious diseases.

Strict hygiene measures for 2 weeks: hand hygiene, wearing underwear at night, morning shower or bath.

On the first day of treatment, wash all sleep wear and bed linen; dust and vacuum.

Anthelmintic drugs do not kill eggs, therefore adequate personal and environmental hygiene is essential to prevent re-infestation from recently swallowed eggs, or eggs already in the environment.

Use clear adhesive tape to recover eggs from the perianal skin and mount on a microscope slide as described below.

• Fold a 5cm long piece of clear adhesive tape sticky side out over the end of a wooden tongue depressor.
• Grip tongue depressor close to edge of tape.
• Press firmly against the perianal region.
• Stick the tape on to a glass microscope slide. Write name and date on slide.
• Place in slide holder for transport to laboratory.