Phthirus Pubis / Crab Louse / Pubic Lice


Peduculosis Pubis is the presence of the crab louse on a human host. This parasitic infestation is commonly referred to as “crabs” or “the cooties”. Pubic lice are remarkably adapted for attachment to coarse body hairs and are grayish-white to pink in color. Crab louse can most often be found in the pubic and perianal areas, but some have been found on other areas of the body, including the eyebrows and eyelashes. The adult crab louse has, approximately, a 30-day lifespan, but can only survive up to 24 hours unattached to a human host. The louse mates frequently and adheres its’ eggs (known as nits) to the base of hairs. The nits require a week to hatch and will grow to adulthood in about 3 weeks.


The first signs of a crab louse infestation are persistent itching, irritation or annoyance in the infested area. Often, pustules form where lice bites have occurred and a severe skin reaction may develop as well. A definite sign of a pubic lice problem is the discovery of small white specks at the base of the hairs in the afflicted area.


It is very unusual to find the crab louse anywhere but on the host, unless the louse is rubbed off or is carried off with a body hair. This is why pubic lice are typically transferred from person to person through sexual contact. Transfer may occur when two people sleep together or maintain other somewhat prolonged bodily contact. Coming into contact with contaminated bedding, clothing, toilet seats, etc. can also transmit the louse, but this is highly unlikely in the case of crab lice.


Non-prescription insecticides which can be used for human louse control include synergized pyrethrins, A-200 Pyrinate, R&S, XXX, Liban, Pronto, Rid, and YDP. Prescription insecticides include Topocide and various Kwell preparations. When any of these compounds is used as directed, it will be extremely effective in destroying both nits and lice. The dead nits can be removed from the hair by combing with a fine comb. Lice found on the eyelids or eyebrows can be removed with tweezers and, in addition, it might be advisable to add some Vaseline to the edge of the eyelids to help kill the crabs. However, it is always best to consult a physician before using any sort of medication. Take note, itching will persist for several days after the application of an effective treatment. All clothing or bedding used throughout the infection should also be washed in hot water or dry-cleaned.

Leave a Reply

You must be logged in to post a comment.