Pubic lice 'crabs'

Question 1

what is the incubation period for pubic lice?

Answer 1

5 days up to several weeks

Question 2

what is the name of the crab lice that causes pubic lice

Answer 2

Phthirus pubis

Question 3

how is pubic lice (phthirus pubis) transmitted

Answer 3

close skin to skin contact, can be sexually transmitted

Question 4

where does pubic lice tend to infest

Answer 4

coarse body hair - beard/moustache, pubic area, body hair, rarely eyebrows and eyelashes

Question 5

what are the symptoms associated with pubic lice

Answer 5

can be asymptomatic

most commonly associated with an intense itch due to the hypersensitivity to feeding lice

Question 6

what signs might you be able to visualise on examination at the lice feeding sites

Answer 6

blue macules (maculae caeruleae)

Question 7

What methods can you use to diagnose pubic lice

Answer 7

usually a clinical diagnose of finding adult lice or eggs

examination of the lice under light microscopy can confirm the diagnosis but not essential

Question 8

What general advice should you give to patients diagnosed with pubic lice?

Answer 8

1. avoid close skin to skin contact and no sex for 1 week after they and their partners have completed treatment
2. wash clothes/beddings and towels on a 60 degree wash to kill the eggs/lice
3. sexual partners, close household contacts need to be seen examined and treated

Question 9

what is the loopback period for pubic lice (phthirus pubis)

Answer 9

3 months

Question 10

Once you have diagnosed pubic lice what other investigations should you do?

Answer 10

offer all patients an STI screen as routine

Question 11

what is the first line treatment option for pubic lice

Answer 11

malathion 0.5% cream

Question 12

What are the general principles of any of the topical treatments used in the treatment of pubic lice that you should advise patients?

Answer 12

Advise patients to apply the lotion/cream to all bodily hair including beard and moustache. Leave to dry for the recommended time before washing off. Repeat the treatment in 3-7 days time.

Question 13

what is the only treatment for pubic lice in pregnancy or breast feeding mothers

Answer 13

permethrin 1% cream

Question 14

list the topical treatment options that can be used in the treatment of pubic lice

Answer 14

1. Malathion 0.5% - apply to dry bodily hair, leave on for 12 hours then wash off, repeat in 3-7 days
2. Permethrin 1% cream - apply to damp hair, leave on for 10 minutes before washing off, repeat in 3-7 days
3. Phenothrin 0.2% - apply to dry hair, leave on for 2 hours before washing off, repeat in 3-7 days
4. Carbaryl - unlicensed, apply to dry hair and wash off 12 hours later, repeat in 3-7 days

Question 15

What treatment can be used if the eyelashes are suspected to be infected with pubic lice

Answer 15

Permethrin 1% lotion - apply to the eyelashes keeping the eyelids closed for 10 minutes. wash off after 10 minutes.

or an inert ophthalmic ointment with white or yellow paraffin which can be applied to eyelashes twice daily for 8-10 days

Question 16

what follow up should you offer patients

Answer 16

offer patients follow up in 1 week following second cycle of treatment to ensure symptoms improving; if treatment failures consider offering an alternative treatment