Section 5-3: Canadian Guidelines on Sexually Transmitted Infections – Management and treatment of specific infections – Ectoparasitic infestations

Section 5 - Management and Treatment of Specific Infections

Ectoparasitic Infestations (Pubic Lice, Scabies)

Pubic Lice

Etiology/Epidemiology
  • Caused by Phthirus pubis (crab louse).
  • Humans are the only reservoir.
  • Shorter life span off host (24 hours) than head lice (several days).
  • Usually present in pubic hair, but may also be found in chest, armpits, eyelashes or facial hair.
  • Transmission occurs through intimate sexual and non-sexual contact.Footnote 1
Prevention and Control
  • Patients presenting with concerns about sexually transmitted infections (STIs) and/or prevention of pregnancy should be provided with instructions and encouragement about the consistent practice of safer-sex.
  • At the time of diagnosis, review and monitor prevention practices.
  • Identify barriers to prevention practices and the means to overcome them.
  • See Primary Care and Sexually Transmitted Infections chapter.
ManifestationsFootnote 2
  • Itching, scratching, erythema, skin irritation and inflammation, all as a reaction to the louse bite.
  • Small blue spots can appear where the louse has bitten.
  • Extensive infestation can be associated with mild fever and malaise.
  • Scratching can lead to a secondary bacterial skin infection.
Diagnosis
  • Based on history and index of suspicion.
  • Careful examination for adult lice and eggs (nits). Look for an area of scabs with nits in the hair; scabs may be adult lice. Nits attach to hair and are not loose and flaky.
Specimen collection and laboratory diagnosis
  • If necessary, submit nits or scabs in a container for microscopic examination.
Management
  • Clothes, bedding and fomites: washing in hot water (50˚C) or dry cleaning kills all stages of lice. Alternatively, place in plastic bags for 1 week.
  • Vacuum mattresses.
  • Sexual partner(s) within the last month should be treated.
  • May re-treat after 1 week if no clinical improvement. Pruritus may be controlled with antihistamines such as hydroxyzine or diphenhydramine, as well as mild topical corticosteroids.Footnote 2
Treatment
  • Wash the affected area and apply pediculocide formulation (cream, lotion or shampoo) according to package instructions.
    • Permethrin 1% cream [A-l]

      OR
    • 0.33% pyrethrin-piperonyl butoxide shampoo [A-l]

      OR
    • lindane 1% shampoo [A-l]Footnote 2,Footnote 3
  • May repeat in 3 -7 days.
Special Considerations
  • Pediculosis of the eyelashes should not be treated with permethrin, pyrethrin or lindane.Footnote 2 Recommended treatment: occlusive ophthalmic ointment to the eyelid margins bid for 10 days.
  • Gamma benzene hexachloride (lindane) can cause neurotoxicity. Instructions for use must be carefully followed to minimize risk of toxicity.Footnote 3 Contraindicated in children <2 years of age, in pregnancy, in lactating women or in patients with extensive dermatitis.
  • Permethrin cream has efficacy similar to lindane 1%, with less toxicity and cure rates greater than 80%.Footnote 3
  • Pruritus may persist for several days or weeks after treatment.
  • In patients with excoriated or damaged skin, consider dose modification to compensate for increased absorption of topical agents.

(See below for Consideration for Other STIs, Reporting and Partner Notification, and Follow-up).

Scabies

Etiology/Epidemiology
  • Caused by Sarcoptes scabiei.
  • Incubation period is 3 weeks, but reinfestation provokes immediate symptoms (1 to 3 days).Footnote 1
  • Transmission:
    • Often non-sexual, through close person-to-person contact (e.g., in families and institutions).Footnote 4
    • May be via shared personal articles (clothes, bedding).
    • Sexual transmission does occur; usually need more than brief contact.
Prevention and Control
  • Patients presenting with concerns about STIs and/or prevention of pregnancy should be provided with instructions and encouragement about the consistent practice of safe-sex.
  • At the time of diagnosis, review and monitor prevention practices.
  • Identify barriers to prevention practices and the means to overcome them.
  • See Primary Care and Sexually Transmitted Infections chapter.
Manifestations
  • Intense nocturnal itching.
  • Burrows under the skin.
  • Lesions affecting hands (finger webs, sides of digits), flexor surfaces of the wrists, axillae, waist, nipple areola, periumbilical area and male genitalia.Footnote 5
  • Papules or nodules, which result from itching, often affect the genital area.
  • Pyoderma of the penis.
  • HIV-infected patients may present atypically with crusted or “exaggerated” scabies called Norwegian scabies.Footnote 6
Diagnosis
  • Based on history, index of suspicion and examination.
  • Diagnosis is often difficult and therefore delayed.
Specimen collection and laboratory diagnosis
  • If necessary, take a skin scraping of a burrow to remove the mite or ova for microscopic examination.Footnote 1
  • Burrow ink test: apply fountain pen ink or a washable marker to outside of burrow, wipe skin (with alcohol). Burrows will retain the ink and may be visualized.Footnote 2
Management
  • Clothes, bedding and fomites: washing in hot water (50˚C) or dry cleaning kills all stages of the organism. Alternatively, place in plastic bags for 3 days to 1 week.Footnote 1
  • Vacuum mattresses.
  • All household contacts and recent sexual partner(s) in the last month should be treated.
  • Pruritus may persist for several weeks. Pruritus may be controlled with antihistamines and mild topical corticosteroids.
Treatment
  • Permethrin 5% cream [A-l].Footnote 2,Footnote 3,Footnote 7
    • Apply to the body from the neck down; leave for 8 to 14 hours; shower and wear clean clothes.
    OR
  • Gamma benzene hexachloride (lindane) 1% cream or lotion [A-l].Footnote 2,Footnote 3,Footnote 7,Footnote 8
    • Apply to the body from the neck down; leave for 8 hours; shower and wear clean clothes.
    • More potential for toxicity than permethrin.
    • Contraindicated in children <2 years of age, in pregnancy, in lactating women or in patients with extensive dermatitis.
  • Alternatives:
    • Crotamiton 10% cream [A-l] (less effective than permethrin or lindane).Footnote 7,Footnote 9 This product is available through the Health Canada Special Access Program.
      • Apply nightly for two nights and wash off thoroughly 24 hours after last application.
      OR
    • Sulphur 5% in petroleum [A-l] (less effective than permethrin or lindane).Footnote 7,Footnote 9
      • Apply nightly for three nights and wash off thoroughly 24 hours after last application.
Special Considerations
  • In pregnancy, permethrin is the only agent that should be used.Footnote 2
  • Gamma benzene hexachloride (lindane) can cause neurotoxicity. Instructions for use must be carefully followed to minimize risk of toxicity.Footnote 3 Contraindicated in children <2 years of age, in pregnancy, in lactating women or in patients with extensive dermatitis.
  • In patients with excoriated or damaged skin, consider dose modification to compensate for increased absorption of topical agents.

Consideration for Other STIs

Reporting and Partner Notification

  • Pubic lice and scabies are not reportable to local public health authorities.
  • Partner notification of ectoparasitic infestations is not required.

Follow-up

  • Follow up only if clinically necessary.

References

Report a problem or mistake on this page
Please select all that apply:

Privacy statement

Thank you for your help!

You will not receive a reply. For enquiries, contact us.

Date modified: