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Symptoms and Signs of Crabs (Pubic Lice)

Doctor's Notes on Crabs
(Pubic Lice)

Pubic lice are parasitic insects found on the genital area hair (pubic hair) of humans. The lice infestation is typically spread by sexual contact, but any skin contact can spread the condition. The lice may occasionally also be found on other areas of body hair. Public lice infestation occurs worldwide. Pubic lice have six legs including two front legs that are very large and look like the pincher claws of a crab. This is the origin of the nickname "crabs." 

Signs and symptoms associated with public lice infestation include intense itching in the genital area. Small lice eggs, known as nits, may be seen attached to the hair shaft. Crawling lice may also occasionally be seen.

Medical Author:
Medically Reviewed on 3/25/2019

(Pubic Lice) Symptoms

  • The main symptoms of infection with the pubic lice of crabs are itching and burning of the pubic area.
  • The itching may spread as the pubic lice move to other moist areas of the body such as the armpit.
  • For many people who have crabs, the itching is worse at night.
  • Intense or prolonged scratching may lead to skin injuries that may become infected by bacteria.

(Pubic Lice) Causes

  • The source of infection for pubic lice is intimate contact with an infected person. Therefore, pubic lice are often transmitted during sex.
  • Since transmission occurs during intimate contact, actual sexual intercourse is not necessary for the spread of pubic lice.
  • Pubic lice can also be transmitted by contact with contaminated belongings such as towels, bed sheets, or clothing.
  • Crabs are transmitted through any intimate contact. Lice do not jump or fly, so actual contact is necessary for transmission. An individual may acquire an infection by sharing bedding or towels.
  • Cats, dogs, and other pets are not involved in the spread of human lice. Your pet cannot become infected with human lice and transmit the lice to another person.

STD Diagnosis, Images, Symptoms, Treatment Slideshow

STD Diagnosis, Images, Symptoms, Treatment Slideshow

It's not necessary to have sexual intercourse to get a sexually-transmitted disease (STD). The human papillomavirus (HPV) that causes genital warts can be transmitted by close skin-to-skin contact. Some types of HPVs cause cervical or anal cancer, and vaccines are available to protect against the most dangerous types. Other HPV types cause genital warts, which can be raised, flat, or cauliflower-shaped. HPV infection can occur in people who have no symptoms or visible warts.

HPV Symptoms

  • Genital warts can be big or small, flat or raised. They generally appear as a small bump or group of bumps in the genital region, and may be shaped like a cauliflower.

HPV Vaccine

  • A vaccine to prevent HPV is given in three shots. The second shot is given a month or two after the first shot. The third shot comes six months after the first shot.
  • The Centers for Disease Control recommends boys and girls be vaccinated at ages 11 or 12.
  • If they did not get the HPV vaccine as children, women can get the HPV vaccine through age 26. Men can get it through age 21. The CDC recommends HPV vaccination for men through age 26 for men who have sex with men or men with compromised immune systems, including HIV.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.