Infestation of humans with lice

3 species affect humans

  • Pediculus humanus capitis: head louse.
  • Pediculus humanus corporis: body louse.
  • Phthirus pubis: pubic or crab louse.

Pediculosis capitis

  • Itching is common
  • Erythema and intensely pruritic papules.
  • Nits attached to hair shafts.
  • Favoured site - behind the ears.
  • Cervical lymphadenopathy common in children.

Pediculosis corporis

  • Itchy papules and excoraitions.
  • Vagabond’s disease.

Pediculosis pubis

  • Lice and nits seen by patient or family members.
  • Attached to the base of the hairs.
  • “maculae caeruleae” slate coloured macules resulting from, intra cutaneous hemorrhages.
  • Head louse: Scalp hair common in children (3 -11 yrs). Head to head contact, sharing combs, brushes and hats.
  • Body louse: Clothes, mainly seams, poor hygiene and unsanitary conditions.
  • Pubic louse: Pubic & axillary hairs, also scalp, eyebrows and eyelashes. Any hairy area. Intimate contact, sexual intercourse and shared clothes.
  • For pediculosis corporis only washing and rinsing all clothes in hot water followed by hot ironing the seams is required.
  • Repeated application of petrolatum on eyelashes & eyebrows, then remove the lice with tweezers.
  • Contacts should be checked and treated.
  • Combs, hair brushes and clothes should not be shared.

How is it diagnosed?

  • Hannifin and Rajki Criteria
  • Diagnostic criteria: Major features
    • Head lice: Presence of live young or adult louse in hair or one or more nits on hair shaft located within 1/4th inch of scalp
    • Body lice: Presence of eggs or crawling lice in the seams of clothing or bedding
    • Pubic lice: Presence of moving lice or nits on hair

How is it treated?

Drug Dose Remark
Malathion 0.5% 12 hrs Repeat after 7 days
Carbaryl Lotion : 24 hrs
Shampoo : 3-4 mins
Repeat after 7 days
GBH 1% lotion : 12 hrs
Shampoo : 4-10 min
2 applications.
Repeat after 7 days
Permethrin 1% 12 hrs Repeat after 7 days

Ivermectin 200 mcg/kg, Cotrimoxazole

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