Morpions/Pubic Lice or Crabs (pthirus inguinalis)

What are pubic lice?

Pubic lice are small flat-bodied insects that look like crabs. They feed on human blood and lay eggs (or nits) on hairs close to the skin.

How do you get pubic lice?

The main source of infection for pubic lice is intimate contact with an infected person. Pubic lice can also be transmitted by contact with contaminated articles such as towels, bed sheets, clothing or personal care products. They infest areas of the body where hair grows, such as the pubis, groin, armpits, anus, beard, eyebrows and eyelashes.

What are the symptoms of pubic lice?

Often there are no symptoms.

Symptoms may include:

  • Itching and skin irritation, especially in the areas covered by pubic hair;
  • Light brown pinhead-size insects visible to the naked eye in the area of the hair shaft;
  • Small gray-white oval eggs (nits) visible to the naked eye in the area of the hair shaft;
  • Small bluish-grey spots resembling bite marks on the affected areas.

What are the possible complications of pubic lice?

The only complications of pubic lice are due to excessive scratching, which may rub the skin raw or trigger a secondary infection in the affected area(s).

How are pubic lice diagnosed?

Pubic lice can be detected by finding adult lice or nits around areas where hair grows.

In case of doubt, ask the advice of a health care professional.

What is the treatment for pulic lice?

  • Apply medication (lotion, cream, shampoo) on the affected areas for 7 to 10 days, or as instructed.
  • Wash clothing and bedding in hot water. Wash bath towels, sheets and any other articles that may have come into contact with the infected areas. In order to eradicate all nits, wash linens and clothing, particularly underwear at a minimum temperature of 60°C. Using an anti-parasitic textile spray is an effective method of disinfestation.
  • Vacuum mattresses and furniture.

How can pubic lice be prevented?

  • Infected individuals should avoid sexual and intimate physical contact for the duration of treatment, so as not to contaminate their partners.
  • Do not share clothing (especially underwear) and towels.
  • Condoms do not offer any protection against these parasites.
  • It is important to inform sexual partners and to encourage them to seek treatment.

What are the risks for HIV-positive people?

There is no associated risk.

Additional information

A follow-up visit may be useful three (3) weeks after treatment to determine the effectiveness of the treatment and to ensure that no re-infection has occurred.

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