Pediculosis pubis

This article is about the disease. For the animal known as crab louse, see Crab louse.

Pediculosis pubis
Other namesCrabs, pubic lice, phthiriasis, phthiriasis pubis
Pubic lice in genital area
SpecialtyInfectious disease
SymptomsItch, scratch marks, grey-blue marks, visible lice and nits
ComplicationsSecondary bacterial infection
Causespubic louse
Risk factorsSexual activity, crowded situations
Diagnostic methodDirect vision of lice with or without magnifying glass
Treatment
  • Application of permethrin containing lotions
  • Removing nits with comb

Pediculosis pubis (also known as "crabs" and "pubic lice") is an infestation by the pubic louse, Pthirus pubis, a wingless insect which feeds on blood and lays its eggs (nits) on mainly pubic hair. Less commonly, hair near the anus, armpit, beard, eyebrows, moustache, and eyelashes may be involved.[1][2][3] It is usually acquired during sex, but can be spread via bedding, clothing and towels, and is more common in crowded conditions where there is close contact between people.[1][4]

The main symptom is an intense itch in the groin, particularly at night. There may be some grey-blue discolouration at the feeding site, and eggs and lice may be visible.[1][2][3] Scratch marks, crusting and scarring may be seen, and there may be signs of secondary bacterial infection.[1]

Diagnosis is by visualising the nits or live lice, either directly or with a magnifying glass.[5] Investigations for other sexually transmitted infections (STIs) are usually performed.[6]

First line treatment usually contains permethrin and is available over the counter.[3] Two rounds of treatment at least a week apart are usually required to kill newly hatched nymphs.[5] Washing bedding and clothing in hot water kills the lice, and transmission can be prevented by avoiding sexual contact until no signs of infestation exist. Eggs may be removed by combing pubic hair with a comb dipped in vinegar.[6] Sexual partners should be evaluated and treated.[6]

Infestation with pubic lice is found in all parts of the world and occurs in all ethnic groups and all levels of society.[6] Worldwide, the condition affects about 2% of the population.[7]

  1. ^ a b c d Cite error: The named reference Lippincott2011 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Salavastru was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference MedlinePlus was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Review07 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Williams2012 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Prevention was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2009 was invoked but never defined (see the help page).