Lice

Background

• Caused by Pediculus humanus
• Hats/combs may act as fomites

Lice (electron microscope)

Clinical Features

• May see live mites or nits (egg sacks) on hair shaft close to scalp
• May be asymptomatic or pruritic

Differential Diagnosis

Ectoparasites

• Bed bugs
• Lice
• Myiasis
• Scabies
• Ticks

Evaluation

• Generally a clinical diagnosis

Management

Over the Counter (OTC)

• Permethrin 1% lotion shampoo (if >2 months old)
  • Wash hair with non-conditioned shampoo
  • Apply Permethrin for 10 min and rinse
  • Repeat on day 9
• Pyrethrin lotion
  • Apply to affected areas and wash off after 10 min
  • Repeat in 7 days

Prescription

Reserved for failed OTC treatment

• Spinosad 0.9% topical suspension (if >6 months old)
  • Apply to scalp and air and wash off after 10 min.
  • Repeat in 10 days
• Malathion 0.5% lotion (if >6 years old)
  • Applied to affected areas and wash after 8 hrs
  • Repeat in 7 days
• Benzyl Alcohol 5% lotion (> 6 months old)
  • Apply to dry hair and wash off after 10 min
  • Repeat in 7 days
• Ivermectin 400mcg/kg PO
  • Once on day 1 THEN once in 7 days
  • Reserved for patients failing topical treatment
• Lindane therapy
  • Only consider if patient has failed two prior prescription treatments
  • Avoid in children <50 kg due to seizure association

Eyelash Infestation

• Apply ophthalmic petroleum jelly q12hrs x 10 days

Pediatrics <2yo

• Wet combing is an alternative to medical therapy

Disposition

• Discharge
• Children can return to school after first topical treatment has been applied
• Instruct parents and all close contacts to wash clothing and bedding in hot soapy water to avoid disease spread

See Also

• Parasitic diseases
• Travel medicine

References

Authors

Ross Donaldson