Phthirus pubis (pubic lice) Flashcards
What is Phthirus pubis?
The crab louse
How is Phthirus pubis acquired?
transmitted by close body contact
What is the typical incubation period of Phthirus pubis?
5 days to several weeks
What are the symptoms and signs of Phthirus pubis?
Adult lice coarse hairs - pubic, body, RARE eyebrows and lashes
Eggs (nits) adhere to hair
Itch
Blue macules
Why does itch occur in infestation with Phthirus pubis?
hypersensitivity to feeding lice
Where do blue macules appear in Phthirus pubis infestation?
visible at feeding sites of lice
Maculae caeruleae
How is Phthirus pubis diagnosed?
Identify adult lice +/or eggs
microscopy can be helpful
What might the limiting factor to treatment of Phthirus pubis be?
Local rotation of topical treatments means getting access to all options may be challenging.
Head lice become resistant to pediculicides hence need for rotation
What is preferred topical formulation for Phthirus pubis?
Lotion rather than shampoo
What topical treatments are available for Phthirus pubis?
Malathion 0.5% - apply DRY hair, leave 2 hours
Permethrin 1% - apply to DAMP hair, wash out 10 min
Phenothrin 0.2%
Carbaryl 0.5-1%
How can Phthirus pubis infestation of eyelashes be treated?
Permethrin lotion keeping eyes shut
OR
ophthalmic ointment with paraffin base - works by suffocation
How often should treatments be applied in Phthirus pubis?
First application followed by SECOND 3-7 days late
How should Phthirus pubis treatment failure be managed?
Alternative therapy to initial treatment
Ensure current sexual partner treated
How far back should contact tracing be for Phthirus pubis?
3 months
