Pediculosis pubis (also known as "crabs" and "pubic lice"[1]) is a disease caused by the pubic louse, Pthirus pubis, a parasiticinsect notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes, causing pediculosis ciliaris. Infestation usually leads to intense itching in the pubic area. Treatment with topic agents such as permethrin or pyrethrin with piperonyl butoxide is exceedingly effective. Worldwide it affects about 2% of the population.
Pubic lice are usually acquired by intimate contact between individuals.[4] Parent-to-child infestations are more likely to occur through routes of shared towels, clothing, beds or closets. Adults are more frequently infested than children. As with most sexually transmitted pathogens, they can only survive a short time away from the warmth and humidity of the human body. Infection in a young child is not necessarily indicative of sexual abuse, although this possibility should be kept in mind.[5][6]
Pubic lice (Phthirus pubis) have three stages: egg, nymph and adult. Eggs (nits) are laid on a hair shaft. Females will lay approximately 30 eggs during their 3–4 week life span. Eggs hatch after about a week and become nymphs, which look like smaller versions of the adults. The nymphs undergo three molts before becoming adults. Adults are 1.5–2.0 mm long and flattened. They are much broader in comparison to head and body lice. Adult lice are found only on the human host and require humanblood to survive. If adults are forced off the host, they will die within 24–48 hours without a blood feeding. Pubic lice are transmitted from person to person most-commonly via sexual contact, although fomites (bedding, clothing) may play a minor role in their transmission.
Pubic lice have three forms: the egg (also called a nit), the nymph, and the adult.
Nit: Nits are lice eggs. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white.
Nymph: The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse but it is smaller. To live, a nymph must feed on blood. It takes 2–3 weeks after hatching to mature into adults capable of reproducing.
Adult: The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their two front legs are very large and look like the pincher claws of a crab. This is how they got the nickname "crabs." Pubic lice are tan to grayish-white in color. Females lay nits and are usually larger than males. To live, lice must feed on blood. If the louse falls off a person, it dies within 1–2 days.[4]
Accurate numbers are difficult to acquire, because pubic lice infestations are not considered a reportable condition by many governments, and many cases are self-treated or treated discreetly by personal physicians.[12]
It has recently been suggested that an increasing percentage of humans removing their pubic hair has led to reduced crab louse populations in some parts of the world.[13][14]
Although any part of the body may be colonized, crab lice favor the hairs of the genital and peri-anal region. Especially in male patients, pubic lice and eggs can also be found in hair on the abdomen and under the armpits as well as on the beard and mustache, while in children they are usually found in eyelashes. Infestation with pubic lice is called Phthiriasis or Pediculosis pubis, while infestation of eyelashes with pubic lice is called Phthriasis palpebrarum[16].
In the majority of infestations, a characteristic grey-blue or slate coloration appears (maculae caeruleae) at the feeding site, which may last for days and is also characteristic for the infestation.
Excoriations, which may become secondarily infected
Maculae cerulea: a pathognomonic finding for pubic lice. These are blue-gray, irregularly shaped macules, which measure 0.5-1 cm in diameter and are usually scattered over the lower abdomen, buttocks and upper thighs.
If the eyelashes are infected, the following are indicated:[edit | edit source]
Recommended regimens should not be applied to the eyes. Apply occlusive ophthalmic ointment or petroleum jelly to the eyelid margins 2 times/day for 10 days
Ivermectin may be used. No teratogenicity has been observed so far in humans, so it remains as low risk during pregnancy and probably compatible during breastfeeding. Despite that, give preference to the other drugs.
Therefore, all partners with whom the patient has had sexual contact within the previous 30 days should be evaluated and treated, and sexual contact should be avoided until all partners have successfully completed treatment and are thought to be cured.[24]
Because of the strong association between the presence of pubic lice and other sexually transmitted infections (STIs), patients diagnosed with pubic lice should undergo evaluation for other STIs.[24]
↑Ronald P. Rapini, Jean L. Bolognia & Joseph L. Jorizzo (2007). Dermatology. St. Louis: Mosby. ISBN1-4160-2999-0.
↑ 2.02.1FRANKS AG, DOBES WL (1946). "DDT in the treatment of scabies, larva migrans and pediculosis pubis". Arch Derm Syphilol. 53: 381. PMID21026349.
↑N. P. Manjunatha, G. R. Jayamanne, S. P. Desai, T. R. Moss, J. Lalik & A. Woodland (2006). "Pediculosis pubis: presentation to ophthalmologist as pthriasis palpebrarum associated with corneal epithelial keratitis". International Journal of STD & AIDS. 17 (6): 424–426. doi:10.1258/095646206777323445.CS1 maint: Multiple names: authors list (link)
↑Varela JA, Otero L, Espinosa E, Sánchez C, Junquera ML, Vázquez F (2003). "Phthirus pubis in a sexually transmitted diseases unit: a study of 14 years". Sex Transm Dis. 30 (4): 292–6. PMID12671547.
↑Manjunatha NP, Jayamanne GR, Desai SP, Moss TR, Lalik J, Woodland A. Pediculosis pubis: presentation to ophthalmologist as pthriasis palpebrarum associated with corneal epithelial keratitis. Int. J. STD AIDS 2006; 17: 424-426
↑ 17.017.1Bennett, John E.; Dolin, Raphael; Blaser, Martin J. (2015). Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Elsevier Inc. ISBN978-1-4557-4801-3.
↑ 18.018.1Gunning K, Pippitt K, Kiraly B, Sayler M (2012). "Pediculosis and scabies: treatment update". Am Fam Physician. 86 (6): 535–41. PMID23062045.