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PekkaAutio

Head Lice and Pubic Lice

Essentials

  • Head lice often spread through hats and caps kept in a coat rack. They are also transmitted from person to person in close contact. Pubic lice are most easily transmitted in sexual contact.
  • If cases of head lice infestation are detected in a day-care centre or a school, the spread of lice should be assessed in the whole community.

Symptoms

  • Itching and red papules in the scalp and pubic hair.
  • Secondary pyodermia often develops in the scalp, and the cervical lymph nodes become enlarged.
  • Pubic lice make red bite marks that cause severe itch in the genital area.
  • In children pubic lice from the parents may reside in the eyelashes, and there may be vague bluish maculae on the trunk ("maculae coerulae").

Diagnosis

  • Nits (louse eggs) are visible in the hair and pubic hair (picture ). Nits can remain in hair for months, which is why only nits found less than 6 mm from the scalp are a definite sign of living parasites (hair grows approximately 1 cm in a month). Nits are best found with a louse comb.
  • Pubic louse nits also typically occur in the hair of the anterior thorax and eyelashes.
  • Do not mix the "hair cast" phenomenon (a ring of dandruff that glides along the hair) with nits. A nit does not glide but is strongly attached to the hair.
  • In children the diagnosis of pubic lice can be based on maculae coerulae and nits in the eyelashes.

Treatment

  • Application of permethrin shampoo according to the instructions in the package.
  • If this is not effective, malathion shampoo or solution can be used.
  • Lotions containing silicone compounds are another alternative. There are several products on the market, and many of them also contain mineral oils or other oil types.
  • Oral ivermectin is effective against head lice Oral Ivermectin for Head Lice. The dose is 200 µg/kg administered twice at a 7-day interval.
  • Nits should be combed away with a louse comb (distance between teeth 0.2-0.3 mm) from the very root of the hair. Other combs and brushes are washed with the above-mentioned shampoos.
  • In daycare centres and schools a communiy health nurse should investigate the head lice situation in the whole community.

For more information: see www http://www.cdc.gov/lice/.

    References

    • Ivermectin for Parasitic Skin Infections of Lice: A Review of Comparative Clinical Effectiveness, Cost-Effectiveness, and Guidelines [Internet].Young C, Argáez C.Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2019 May 14.
    • Salavastru CM, Chosidow O, Janier M et al. European guideline for the management of pediculosis pubis. J Eur Acad Dermatol Venereol 2017;31(9):1425-1428. [PubMed]