A magnified crab louse
Find information on thousands of medical conditions and prescription drugs.

Pubic lice

Crab lice (singular, louse), scientific name Phthirus pubis and commonly called "crabs" due to their resemblence to the crab, are one of three kinds of human lice in the large group of lice families, the others being head lice and body lice, which live in clothing. more...

Bubonic plague
Pacman syndrome
Paget's disease of bone
Paget's disease of the...
Palmoplantar Keratoderma
Pancreas divisum
Pancreatic cancer
Panic disorder
Paramyotonia congenita
Parkinson's disease
Parkinson's disease
Paroxysmal nocturnal...
Patau syndrome
Patent ductus arteriosus
Pelizaeus-Merzbacher disease
Pelvic inflammatory disease
Pelvic lipomatosis
Pendred syndrome
Periarteritis nodosa
Perinatal infections
Periodontal disease
Peripartum cardiomyopathy
Peripheral neuropathy
Periventricular leukomalacia
Pernicious anemia
Persistent sexual arousal...
Pes planus
Peutz-Jeghers syndrome
Peyronie disease
Pfeiffer syndrome
Photosensitive epilepsy
Pica (disorder)
Pickardt syndrome
Pili multigemini
Pilonidal cyst
Pityriasis lichenoides...
Pityriasis lichenoides et...
Pityriasis rubra pilaris
Placental abruption
Pleural effusion
Plummer-Vinson syndrome
Pneumocystis jiroveci...
Pneumonia, eosinophilic
POEMS syndrome
Poland syndrome
Polyarteritis nodosa
Polycystic kidney disease
Polycystic ovarian syndrome
Polycythemia vera
Polymyalgia rheumatica
Polyostotic fibrous...
Pompe's disease
Popliteal pterygium syndrome
Porphyria cutanea tarda
Portal hypertension
Portal vein thrombosis
Post Polio syndrome
Post-traumatic stress...
Postural hypotension
Poxviridae disease
Prader-Willi syndrome
Precocious puberty
Premature aging
Premenstrual dysphoric...
Primary biliary cirrhosis
Primary ciliary dyskinesia
Primary hyperparathyroidism
Primary lateral sclerosis
Primary progressive aphasia
Primary pulmonary...
Primary sclerosing...
Prinzmetal's variant angina
Proconvertin deficiency,...
Progressive external...
Progressive multifocal...
Progressive supranuclear...
Protein S deficiency
Protein-energy malnutrition
Proteus syndrome
Prune belly syndrome
Pseudomyxoma peritonei
Pseudotumor cerebri
Pseudoxanthoma elasticum
Psychogenic polydipsia
Psychophysiologic Disorders
Pubic lice
Puerperal fever
Pulmonary alveolar...
Pulmonary hypertension
Pulmonary sequestration
Pulmonary valve stenosis
Pulmonic stenosis
Pure red cell aplasia
Purpura, Schoenlein-Henoch
Purpura, thrombotic...
Pyoderma gangrenosum
Pyruvate kinase deficiency

They are wingless, about 1 to 3 mm long. They attach themselves to hair strands, and hatch out of pods with lids, or "nits", that are too tightly attached to be brushed off but must be removed by pulling with the nails or a fine-toothed comb.

General information

The crab louse can live in almost any form of humanoid hair, but is found most commonly in pubic hair, leading to its other common name of pubic louse. Its legs are adapted to climbing along relatively widely spaced hairs, and so can be found in eyelashes, pubic hair, beards, moustaches, and even armpit hairs. The individual louse can survive up to a week apart from its necessary human host, so that crab lice can be passed on in sleeping bags and bedding. The female may lay up to 40 eggs a time, resulting in a fluctuating but growing population. The louse feeds on blood and can leave irritating spots on the skin, sometimes mistaken for pimples, a condition called Pediculosis pubis.

Pubic lice have legs that are spaced further apart than head lice, this is an adaptation that enables them to move around more easily in their habitat.

The female louse glues her eggs, called "nits", which look like tiny white beads, to hair shafts. Lice bite through the skin to suck blood, and the bite causes itching. Bites can become secondarily infected; scratching may break the skin and help cause secondary infection. The most common symptom of crab lice is itching of genital area.

Pubic lice are normally spread by sexual contact and are considered a sexually transmitted disease, but can also be spread by sharing clothes or bedding. A common misbelief is that infestation can be spread by sitting on a toilet seat. This is not likely since lice cannot live long away from a warm human body. Also, lice do not have feet designed to walk or hold onto smooth surfaces such as toilet seats.

Life cycle

There are three stages in the life of a pubic louse: the nit, the nymph, and the adult.

  • Nit: Nits are pubic lice eggs. They are hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Nits take about 1 week to hatch.
  • Nymph: The nit hatches into a baby louse called a nymph. It looks like an adult pubic louse, but is smaller. Nymphs mature into adults about 7 days after hatching. To live, the nymph must feed on blood.
  • Adult: The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs, but their two front legs are very large and look like the pincher claws of a crab; this how they got the nickname "crabs." Pubic lice are tan to greyish-white in color. Females lay nits; they are usually larger than males. To live, adult lice need to feed on blood. If the louse falls off a person, it dies within 1-2 days.

Read more at Wikipedia.org

[List your site here Free!]

Lice infestation
From Gale Encyclopedia of Alternative Medicine, 4/6/01 by Mai Tran


Lice infestations (pediculosis) are infections of the skin, hair, or genital region caused by lice living directly on the body or in hats or other garments. Lice are small wingless insect-like parasites with sucking mouthparts that feed on human blood and lay their eggs on body hairs or in clothing. The name pediculosis comes from the Latin word for louse (singular) or lice (plural).


Lice infestations are not dangerous infections by themselves. They are, however, a serious public health problem because some lice can carry organisms that cause other diseases, including relapsing fever, trench fever, and epidemic typhus. Although trench fever is self-limiting, the other two diseases have mortality rates of 5%-10%. Pubic lice are often associated with other sexually transmitted diseases (STDs), but lice do not spread these diseases.

Lice infestations are frequent occurrences in areas of overcrowding or inadequate facilities for bathing and laundry. They are often associated with homelessness in the general population or with military, refugee, or prisoner camps in war-torn areas. All humans are equally susceptible to louse infestation; the elderly, however, are more vulnerable to typhus and other diseases carried by lice.

Causes & symptoms

The symptoms of lice infestations vary somewhat according to body location, although all are characterized by intense itching, usually with injury to the skin caused by scratching or scraping. The itching is an allergic reaction to a toxin in the saliva of the lice. Repeated bites can lead to a generalized skin eruption or inflammation.

Head lice

This type of infestation is caused by Pediculosis humanus capitis, the head louse. Head lice can be transmitted from one person to another by sharing of hats, combs, or hair brushes. Epidemics of head lice are common among school-age children from all class backgrounds in all parts of the United States. The head louse is about 1/16 of an inch in length. The adult form may be visible on the patient's scalp, especially around the ears; or its grayish-white nits (eggs) may be visible at the base of the hairs close to the scalp. It takes between three and 14 days for the nits to hatch. After the nits hatch, the louse must feed on blood within a day or die.

Head lice can spread from the scalp to the eyebrows, eyelashes, and beard in adults, although they are more often limited to the scalp in children. The itching may be intense, and may be followed by bacterial infection of skin that has been scratched open. Another common complication is swelling or inflammation of the neck glands. Head lice do not spread typhus or other systemic diseases.

Body lice

Infestations of body lice are caused by Pediculosis humanus corporis, an organism that is similar in size to head lice. Body lice, however, are rarely seen on the skin itself because they come to the skin only to feed. They should be looked for in the seams of the patient's clothing. This type of infestation is associated with wearing the same clothing for long periods of time without laundering, as may happen in wartime or in cold climates; or with poor personal hygiene. It can be spread by close personal contact or shared bedding.

Patients with body lice often have intense itching with deep scratches around the upper shoulders, flanks, or neck. The bites first appear as small red pimples but may cause a generalized skin rash. If the infestation is not treated, the patient may develop complications that include headache, fever, and bacterial infection with scarring. Body lice can spread systemic typhus or other infections.

Pubic lice

Pubic lice are sometimes called "crabs." This type of infestation is caused by Phthirus pubis and is commonly spread by intimate contact. People can also get pubic lice from using the bedding, towels, or clothes of an infected person.

Pubic lice usually appear first on pubic hair, but may spread to other parts of the body, particularly if the patient is very hairy. Pubic lice are also sometimes seen on the eyelashes of children born to infected mothers. It is usually easier for the doctor to see marks from the patient's scratching than the bites from the lice, but pubic lice sometimes produce small bluish spots called maculae ceruleae on the patient's trunk or thighs. Pubic lice also sometimes leave small dark brown specks from their own excreted matter on the parts of the patient's underwear that cover the anal or genital areas.


Doctors can diagnose lice infestations from looking closely at the parts of the body where the patient has been scratching. Lice are large enough to be easily seen with the naked eye or a magnifying glass. The eggs of pubic lice as well as head lice can often be found by looking at the base of the patient's hairs. Pediatricians are most likely to diagnose lice in school-age children.

It is important for doctors to rule out other diseases that can cause scratching and skin inflammation because the medications used to kill lice are very strong and can have bothersome side effects. The doctor will need to distinguish between head lice and dandruff; between body lice and scabies (a disease caused by skin mites); and between pubic lice and eczema. Blood tests or other laboratory tests are not useful in diagnosing lice infestations.


For pubic lice, some practitioners of holistic medicine recommend a mixture of 25% oil of pennyroyal (Mentha pulegium), 25% garlic (Allium sativum) oil, and 50% distilled water applied three times in a three-day period, followed by removal of dormant eggs to prevent reinfestation.

For herbal treatments of head lice, parents should carefully brush the child's head with a homemade mixture of olive oil and lavender essential oil at the ratio of 3 to 1. A small area should be tested before applying to check for allergic sensitivity or skin reaction. This is followed by a vinegar rinse to unglue the nits from the hair. Then, using a fine-tooth comb, parents should comb the child's hair meticulously to comb away the eggs from the hair shaft. And finally, they should wash the child's hair with normal shampoo.

Allopathic treatment

Cases of head lice are usually treated with shampoos or rinses containing either lindane (Kwell) or permethrin (Nix). Because lindane is absorbed through the skin, the person applying the treatment should wear rubber gloves and rinse the patient's hair or body completely after use. Following the treatment, nits should be removed from the hair with a fine-toothed comb or tweezers. Lindane is also effective for treating infestations of body or pubic lice, but it should not be used by pregnant women. In most cases one treatment is sufficient, but the medication can be reapplied a week later if living lice have reappeared.

Infestations of body lice can also be treated by washing the patient's clothes or bedding in boiling water, ironing seams on a high setting, or treating the clothes with 1% malathion powder or 10% DDT powder.

If the patient's eyelashes have been infested, the only safe treatments are either a thick coating of petroleum jelly (Vaseline) applied twice daily for eight days, or 1% yellow oxide of mercury applied four times a day for two weeks. Any remaining nits should be removed with tweezers.

Patients with pubic lice should be examined and tested for other STDs.

Expected results

Lice can be successfully eradicated in almost all cases, although some cases of lindane-resistant lice have been reported. In general, patients are more at risk from typhus and other diseases spread by lice than from the lice themselves.


There are no vaccines or skin treatments that will protect a person against lice prior to contact. In addition, lice infestation does not provide immunity against reinfection; recurrences are in fact quite common. Prevention depends on adequate personal hygiene at the individual level and the following public health measures:

  • Teaching school-age children the basics of good personal hygiene, including the importance of not lending or borrowing combs, brushes, or hats.
  • Notifying and treating an adult patient's close personal and sexual contacts.
  • Examining homeless people, elderly patients incapable of self-care, and other high-risk individuals prior to hospital admission for signs of louse infestation. This measure is necessary to protect other hospitalized people from the spread of lice.

Key Terms

An informal or slang term for pubic lice.
A benzene compound that is used to kill body and pubic lice. Lindane works by being absorbed into the louse's central nervous system, causing seizures and death.
Maculae ceruleae
Bluish or blue-gray skin eruptions often seen on the trunk or thighs of patients with pubic lice. The Latin words mean blue spots.
An insecticide that can be used in 1% powdered form to disinfect the clothes of patients with body lice.
The eggs produced by head or pubic lice, usually grayish-white in color and visible at the base of hair shafts.

A medication used to rid the scalp of head lice. Permethrin works by paralyzing the lice, so that they cannot feed after hatching within the 24 hours required for survival.

Further Reading

For Your Information


  • Berger, Timothy G. "Skin & Appendages." In Current Medical Diagnosis & Treatment 1998. Edited by Lawrence M. Tierney, Jr., et al. Stamford, CT: Appleton & Lange, 1997.
  • The Burton Goldberg Group. "Children's Health." Alternative Medicine: The Definitive Guide. Tiburon, CA: Future Medicine Publishing, Inc.
  • "Dermatologic Disorders: Parasitic Infections of the Skin." In The Merck Manual of Diagnosis and Therapy. Edited by Robert Berkow, et al. Rahway, NJ: Merck Research Laboratories, 1992.
  • "Lindane." In Nurses Drug Guide 1995. Edited by Billie Ann Wilson, et al. Norwalk, CT: Appleton & Lange, 1995.
  • McCarthy, James S., and Thomas B. Nutman "Parasitic Diseases of the Skin." In Conn's Current Therapy. Edited by Robert E. Rakel. Philadelphia: W. B. Saunders Company, 1997.
  • Millikin, Larry E. "Flies, Lice, Mites, and Bites." In Current Diagnosis 9, edited by Rex B. Conn, et al. Philadelphia: W. B. Saunders Company, 1997.
  • Morelli, Joseph G., and William L. Weston. "Skin." In Current Pediatric Diagnosis & Treatment. Edited by William W. Hay, Jr., et al. Stamford,CT: Appleton & Lange, 1997.
  • "Permethrin." In Nurses Drug Guide 1995. Edited by Billie Ann Wilson, et al. Norwalk, CT: Appleton & Lange, 1995.

Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.

Return to Pubic lice
Home Contact Resources Exchange Links ebay