{{Short description|Infestation by the pubic louse}} {{About|the disease|the animal known as crab louse|Crab louse}} {{use dmy dates|date=December 2017}} {{use American English|date=December 2017}} {{Infobox medical condition (new) | name = Pediculosis pubis | synonyms = Crabs, pubic lice, phthiriasis, phthiriasis pubis | image = SOA-Pediculosis-pubis.jpg | caption = Pubic lice in genital area | pronounce = | field = Infectious disease | symptoms = Itch, scratch marks, grey-blue marks, visible lice and nits | complications = Secondary bacterial infection | onset = | duration = | types = | causes = Pubic louse | risks = Sexual activity, crowded situations | diagnosis = Direct vision of lice with or without magnifying glass | differential = | prevention = | treatment = *Application of permethrin containing lotions * Removing nits with comb | medication = | prognosis = | frequency = | deaths = }} <!-- Definition -->
'''''Pediculosis pubis''''' (also known as "'''crabs'''" and "'''pubic lice'''") is an infestation by the pubic louse also known as the crab 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.<ref name="Lippincott2011" /><ref name="Salavastru" /><ref name="MedlinePlus" /> 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.<ref name="Lippincott2011" /><ref name="Review07" />
<!-- Signs and symptoms --> 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.<ref name="Lippincott2011"/><ref name=Salavastru/><ref name=MedlinePlus/> Scratch marks, crusting and scarring may be seen, and there may be signs of secondary bacterial infection.<ref name="Lippincott2011"/>
<!-- Diagnosis --> Diagnosis is by visualising the nits or live lice, either directly or with a magnifying glass.<ref name="Williams2012" /> Investigations for other sexually transmitted infections (STIs) are usually performed.<ref name="Prevention" />
<!-- Treatment --> First line treatment usually contains permethrin and is available over the counter.<ref name=MedlinePlus/> Two rounds of treatment at least a week apart are usually required to kill newly hatched nymphs.<ref name="Williams2012" /> 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.<ref name="Prevention" /> Sexual partners should be evaluated and treated.<ref name="Prevention" />
<!-- Epidemiology --> Infestation with pubic lice is found in all parts of the world and occurs in all ethnic groups and all levels of society.<ref name="Prevention" /> Worldwide, the condition affects about 2% of the population.<ref name=Anderson2009/>
==Signs and symptoms== The onset of symptoms is typically three weeks after the first infestation of lice and is mainly an intense itch in the pubic area and groin, particularly at night, resulting from an allergic reaction to the saliva of feeding lice.<ref name="Lippincott2011"/><ref name=Review07/><ref name=NHS>{{Cite web|date=19 October 2017|title=Pubic lice|url=https://www.nhs.uk/conditions/pubic-lice/|access-date=13 November 2020|website=nhs.uk|language=en}}</ref> In some infestations, a characteristic grey-blue or slate coloration macule appears (''maculae caeruleae'') at the feeding site, which may last for days. Nits or live lice may be seen crawling on the skin.<ref name=MedlinePlus/><ref name="Alexander2012">{{cite book|last=O'Donel Alexander|first=John|title=Arthropods and Human Skin|chapter-url=https://books.google.com/books?id=vTXTBwAAQBAJ&pg=PP29|date=2012|publisher=Springer Verlag|location=Berlin|isbn=978-1-4471-1358-4|pages=29–53|chapter=5. Infestation with Anoplura- Lice}}</ref><ref name="Prevention">{{Cite web|url=https://www.cdc.gov/parasites/lice/pubic/gen_info/faqs.html|title=CDC - Lice - Pubic|last=Prevention|first=CDC - Centers for Disease Control and|website=www.cdc.gov|language=en-us|access-date=2017-12-04|date=2017-05-02}}{{PD-notice}}</ref> Louse droppings may be noticed as a black powder in the underwear.<ref name=NHS/>
Scratch marks, crusting, scarring, rust-colored faecal material, blood stained underwear and secondary bacterial infection may sometimes be seen. Large lymph nodes in the groin and armpits may be felt.<ref name="Lippincott2011"/> Some people with pubic lice infestation may not have any symptoms.<ref name="Alexander2012"/>
<gallery> File:Lice Pubic.png|Pubic lice lay eggs on hair shaft. File:Fig. 2. Pubic lice in abdomen.jpg|Pubic lice on the abdomen File:Pubic lice on eye-lashes.jpg|Pubic lice on the eyelashes </gallery> ===Complications=== Complications are usually as a result of persistent scratching and include thickening of the skin, darkened skin, and secondary bacterial infection including impetigo, conjunctivitis and blepharitis.<ref name="Lippincott2011"/><ref name="NHS" />
==Causes== ===Spread=== Pubic lice are usually transmitted from one person to another during vaginal, oral, anal or manual sex, whether a condom is used or not.<ref name=Review07/><ref name=NHS/><ref>{{cite book| last = Corinna | first = Heather |authorlink=Heather Corinna |title=S.E.X. The All-You-Need-to-Know Progressive Sexuality Guide to Get You Through High School and College|publisher=Da Capo Press|year=2007|page=204|access-date=October 23, 2023|isbn=978-1-60094-010-1|url=https://books.google.com/books?id=L_GlCAAAQBAJ&pg=PA204}}</ref> One sexual encounter with an infected person carries a high risk of catching pubic lice.<ref name="Ferri2015">{{cite book|author=Fred F. Ferri|title=Ferri's Clinical Advisor 2016: 5 Books in 1|url=https://books.google.com/books?id=bbLSCQAAQBAJ&pg=PA936|year=2015|publisher=Elsevier Health Sciences|isbn=978-0-323-37822-2|page=936}}</ref> In some circumstances transmission can occur through kissing and hugging, and less likely via bedding, clothing and towels. The lice spread more easily in crowded conditions where the distance between people is close, allowing the lice to crawl from one person to another.<ref name="Lippincott2011"/><ref name=NHS/>
Infestation on the eyebrows or eyelashes of a child may indicate sexual exposure or abuse.<ref name="Prevention" />
===Characteristics and life cycle=== {{Main|Crab louse}} thumb|upright=1.36|Crab lice Pubic lice (''Pthirus pubis'') have three stages: the egg (also called a nit), the nymph, and the adult. They can be hard to see and are found firmly attached to the hair shaft. They are oval and usually yellow to white. Pubic lice nits take about 6–10 days to hatch. The nymph is an immature louse that hatches from the nit (egg). A nymph looks like an adult pubic louse but it is smaller. Pubic lice nymphs take about 2–3 weeks after hatching to mature into adults capable of reproducing. To live, a nymph must feed on blood. The adult pubic louse resembles a miniature crab when viewed through a strong magnifying glass. Pubic lice have six legs; their four rear legs are very large and are reminiscent of the pincher claws of a crab—thus the nickname "crabs". Pubic lice are tan to grayish-white in color. Females lay nits and are usually larger than males.<ref name="Prevention"/> To live, lice must feed on blood. If the louse falls off a person, it dies within 1–2 days. 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. Adults are found only on the human host and require human blood to survive. 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.<ref name=Review07>{{cite journal |author=P. A. Leone |title=Scabies and pediculosis pubis: an update of treatment regimens and general review |journal=Clinical Infectious Diseases |volume=44 |issue=Suppl. 3 |pages=S153–S159 |year=2007 |pmid=17342668 |doi=10.1086/511428|doi-access=free}}</ref><ref>{{Cite web |url=https://www.cdc.gov/parasites/lice/pubic/biology.html |title=CDC - Lice - Pubic "Crab" Lice - Biology |date=26 June 2019 |website=www.cdc.gov |publisher=Centers for Disease Control and Prevention (CDC) |language=en-us |access-date=29 October 2020}}{{PD-notice}}</ref>
==Diagnosis== Diagnosis is made by carefully looking at the pubic hair for nits, young lice and adult lice.<ref name=Review07/> Lice and nits can be removed either with forceps or by cutting the infested hair with scissors (with the exception of an infestation of the eye area).<ref name="Williams2012" /> A magnifying glass, dermatoscope or a stereo-microscope can be used for identification.<ref name="Salavastru" /><ref name="Williams2012" >{{Cite book|url=https://books.google.com/books?id=QFTeEWbqTbgC|title=Williams gynecology|date=2012|publisher=McGraw-Hill Medical|others=Hoffman, Barbara L., Williams, J. Whitridge (John Whitridge), 1866-1931.|isbn=9780071716727|edition=2nd|location=New York|pages=90–91|oclc=779244257}}</ref> Testing for other sexually transmitted infections is recommended in those who are infested with pubic lice.<ref name=Review07/> ===Definition=== Pediculosis pubis 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.<ref name="Lippincott2011">{{cite book|chapter-url=https://books.google.com/books?id=ZF-eoG18XXAC&pg=PA236|title=Lippincott's Guide to Infectious Diseases|publisher=Lippincott Williams & Wilkins|year=2011|isbn=978-1-60547-975-0|page=236|chapter=Pediculosis}}</ref><ref name=Salavastru>{{Cite journal|last1=Salavastru|first1=C. M.|last2=Chosidow|first2=O.|last3=Janier|first3=M.|last4=Tiplica|first4=G. S.|date=2017|title=European guideline for the management of pediculosis pubis|journal=Journal of the European Academy of Dermatology and Venereology|language=en|volume=31|issue=9|pages=1425–1428|doi=10.1111/jdv.14420|pmid=28714128|issn=1468-3083|doi-access=free}}</ref><ref name=MedlinePlus/> Although the presence of pubic lice is associated with the presence of other sexually transmitted diseases, pubic lice are not known to spread infectious diseases.<ref name="Gratz2006">{{cite book|last=Gratz|first=Norman|title=Vector- and Rodent-Borne Diseases in Europe and North America: Distribution, Public Health Burden, and Control|url=https://books.google.com/books?id=-2FKGcbeHA8C&pg=PA87|year=2006|publisher=Cambridge University Press|isbn=978-0-521-85447-4|page=87}}</ref>
==Treatment== Pubic lice can be treated at home. Available treatments may vary from country to country and include mainly permethrin-containing creams and lotions applied to cool dry skin or applying dimethicone-based oils.<ref name=Salavastru/>
Treatment with medication is combined with combing pubic hair with a fine-toothed comb after applying vinegar directly to skin or dipping the comb in vinegar, to remove nits.<ref name="Lippincott2011" /><ref name=MedlinePlus/> It is recommended to wash bedding, clothing and towels in hot water or preferably in a washing machine at 50°C or higher. When this is not possible, the clothing can be stored in a sealed plastic bag for at least three days.<ref name=Salavastru/><ref name="CDC2015" /> Re-infestation can be prevented by wearing clean underwear at the start of treatment and after completing treatment.<ref name=Salavastru/> Shaving the affected hair is not essential.<ref name=Salavastru/>
===First line=== thumb|Nit comb At first, treatment is usually with topical permethrin 1% cream, which can be bought over the counter without a prescription. It is applied to the areas affected by pubic lice and washed off after 10 minutes.<ref name="Prevention" /> Brands of permethrin include 'Lyclear', available in the UK as a creme rinse or dermal cream at 5% strengths.<ref name=Permethrin>[https://www.medicines.org.uk/emc/search?q=permethrin Patient Information Leaflet: Permethrin] {{webarchive|url=https://web.archive.org/web/20201127084340/https://www.medicines.org.uk/emc/search?q=permethrin |date=27 November 2020}}, Archived on the Electronic Medicines Compendium of the UK. Accessed 27 November 2020.</ref><ref>{{Cite book|url=https://apps.who.int/iris/rest/bitstreams/1237479/retrieve|title=World Health Organization Model List of Essential Medicines: 21st list|publisher=WHO|year=2019|pages=38}}</ref> In the US, common permethrin brands include NIX, Actin and Elimite.<ref name=Guenther>{{Cite web|last=Guenther|first=Lyn C C|date=16 August 2019|title=Pediculosis and Pthiriasis (Lice Infestation) Medication: Antiparasitic Agents|url=https://emedicine.medscape.com/article/225013-medication#2|access-date=27 November 2020|website=emedicine.medscape.com}}</ref>
An alternative is the combination of pyrethrins and piperonyl butoxide, in a topical application, which include the brands Licide, and A-200, Pronto and RID shampoos.<ref name="CDC2015" /><ref name=MedlPlus>{{Cite web|title=Pyrethrin and Piperonyl Butoxide Topical: MedlinePlus Drug Information|url=https://medlineplus.gov/druginfo/meds/a601105.html|access-date=23 November 2020|website=medlineplus.gov|language=en}}. Last revised 15 November 2015. </ref> These medications are safe and effective when used exactly according to the instructions in the package or on the label.<ref name="Prevention" /> To kill newly hatched lice, both treatments can be repeated within the following seven to ten days.<ref name="Williams2012" /><ref name="ButtaravoliHudson2012">{{cite book|last1=Buttaravoli|first1=Philip |last2=Hudson|first2=Page|editor=Philip Buttaravoli|others=Stephen M. Leffler|title=Minor Emergencies E-Book|chapter-url=https://books.google.com/books?id=bU-7t1G7ISQC&pg=PA701|edition=Third|year=2012|publisher=Elsevier Saunders|isbn=978-0-323-07909-9|page=701|chapter=178. Pediculosis (lice, crabs)}}</ref>
European guidelines state alternatives to permethrin as including either the application of 0.2% phenothrin (washed off after two hours), or 0.5% malathion lotions (washed off after 12 hours).<ref name="Salavastru" /> The CDC states alternatives as topical 0.5% malathion or oral ivermectin.<ref name=CDC2015>{{Cite web|date=2019-01-11|title=Ectoparasitic Infections - 2015 STD Treatment Guidelines|url=https://www.cdc.gov/std/tg2015/ectoparasitic.htm|access-date=20 November 2020|website=www.cdc.gov|language=en-us}}</ref>
===Other treatments=== Lindane is still used in a shampoo form in some non-European countries. Its licence was withdrawn by the European Medicines Agency in 2008.<ref name=Salavastru/> It may be considered as a last resort in some people who show resistance to other treatments, but is not recommended to be used for a second round of treatment.<ref name=Salavastru/><ref name="Review07" /> Lindane is not recommended in pregnant and breastfeeding women, children under the age of two years, and people who have extensive dermatitis.<ref name=Review07/><ref name="Prevention" /> The FDA warns against use in people with a history of uncontrolled seizure disorders and cautious use in infants, children, the elderly, and individuals with other skin conditions (e.g., atopic dermatitis, psoriasis) and in those who weigh less than 110 lbs (50 kg).<ref name="Prevention" /><ref name=FDALindane>[https://web.archive.org/web/20090818051553/http://www.accessdata.fda.gov/drugsatfda_docs/label/2003/006309shampoolbl.pdf "Lindane Shampoo, USP, 1%"]. FDA. 2002</ref> Carbaryl has been used since 1976 but found to have the potential to cause cancer in rodents and not to be as effective as previously thought. It is either not used at all or its use is restricted.<ref name=Salavastru/><ref name=Sangaré2016>{{Cite journal|last1=Sangaré|first1=Abdoul Karim|last2=Doumbo|first2=Ogobara K.|last3=Raoult|first3=Didier|date=2016|title=Management and Treatment of Human Lice|journal=BioMed Research International|volume=2016|pages=1–12|doi=10.1155/2016/8962685|issn=2314-6133|pmc=4978820|pmid=27529073|doi-access=free}}</ref>
Sexual partners should be evaluated and treated, and sexual contact should be avoided until all partners are better. Because of the strong association between the presence of pubic lice and sexually transmitted infections (STIs), affected people require investigation for other STIs.<ref name="Prevention" />
===Eyes=== Infestation of the eyes is treated differently from other parts of the body. Lice can be removed with forceps or by removing or trimming the lashes.<ref name="Rook2016">{{cite book|last1=Saw|first1=P. J.|chapter-url=https://books.google.com/books?id=85AvCgAAQBAJ&pg=PR42|title=Rook's Textbook of Dermatology, 4 Volume Set|last2=Leonard|first2=Jonathan|publisher=John Wiley & Sons|year=2016|isbn=978-1-118-44119-0|editor-last=Griffiths|editor-first=Christopher|volume=3|page=42|chapter=109. Dermatoses of the eye, eyelids and eyebrows|editor-last2=Barker|editor-first2=Jonathan|editor-last3=Bleiker|editor-first3=Tanya O.|editor-last4=Chalmers|editor-first4=Robert|editor-last5=Creamer|editor-first5=Daniel}}</ref> Eyelashes may be treated with a gentle petroleum jelly for occlusion.<ref name="Rook2016"/>
==Epidemiology== Infestation with pubic lice is found in all parts of the world, occurs in all ethnic groups and all levels of society.<ref name="Prevention" />
Current worldwide prevalence has been very approximately estimated at two percent of the human population. Accurate numbers are difficult to acquire, because pubic lice infestations are not considered a reportable condition by many governments. Many cases are self-treated or treated discreetly by personal physicians, which further adds to the difficulty of producing accurate statistics.<ref name=Anderson2009>{{cite journal |author1=Alice L. Anderson |author2=Elizabeth Chaney |year=2009 |title=Pubic lice (''Pthirus pubis''): history, biology and treatment vs. knowledge and beliefs of US College students |journal=International Journal of Environmental Research and Public Health |volume=6 |issue=2 |pages=592–600 |pmid=19440402 |pmc=2672365 |doi=10.3390/ijerph6020592 |doi-access=free }}</ref>
It has been reported that the trend of pubic hair removal has led to the destruction of the natural habitat of the crab louse populations in some parts of the world, thereby reducing the incidence of the disease.<ref name="Salavastru" /><ref>{{cite journal |author1=N. R. Armstrong |author2=J. D. Wilson |year=2006 |title=Did the "Brazilian" kill the pubic louse? |journal=Sexually Transmitted Infections |volume=82 |issue=3 |pages=265–266 |doi=10.1136/sti.2005.018671 |pmid=16731684 |pmc=2564756}}</ref><ref>Bloomberg: [https://www.bloomberg.com/news/2013-01-13/brazilian-bikini-waxes-make-crab-lice-endangered-species-health.html Brazilian bikini waxes make crab lice endangered species], published 13 January 2013, retrieved 14 January 2013</ref>
==Etymology == Infestation with pubic lice is also called '''''phthiriasis''''' or '''''phthiriasis pubis''''', while infestation of eyelashes with pubic lice is called ''phthiriasis palpebrarum'' or ''pediculosis ciliarum''.<ref>{{cite journal |author1=N. P. Manjunatha |author2=G. R. Jayamanne |author3=S. P. Desai |author4=T. R. Moss |author5=J. Lalik |author6=A. Woodland |year=2006 |title=Pediculosis pubis: presentation to ophthalmologist as pthriasis palpebrarum associated with corneal epithelial keratitis |journal=International Journal of STD & AIDS |volume=17 |issue=6 |pages=424–426 |doi=10.1258/095646206777323445|pmid=16734970 |s2cid=10551175 }}</ref> Linnaeus was first to describe and name the pubic louse in 1758, when he called it Pediculus pubis. The disease is spelled with ''phth'', but the scientific name of the louse ''Pthirus pubis'' is spelled with ''pth'' (an etymologically incorrect spelling that was nonetheless officially adopted in 1958).<ref name=Taxonomy>{{Cite web|title=Taxonomy of Human Lice {{!}} Phthiraptera.info|url=http://phthiraptera.info/content/taxonomy-human-lice|access-date=9 November 2020|website=phthiraptera.info|archive-date=14 April 2020|archive-url=https://web.archive.org/web/20200414211109/http://phthiraptera.info/content/taxonomy-human-lice|url-status=dead}}</ref>
==Other animals== Humans are the only known hosts of this parasite,<ref name=MedlinePlus>{{Cite web|url=https://medlineplus.gov/ency/article/000841.htm|title=Pubic lice: MedlinePlus Medical Encyclopedia|website=medlineplus.gov|language=en|access-date=2017-12-04}}{{PD-notice}}</ref> although a closely related species, ''Pthirus gorillae'', infects gorilla populations.<ref>{{cite journal |author=Robin A. Weiss |year=2009 |title=Apes, lice and prehistory |journal=Journal of Biology |volume=8 |issue=2 |page=20 |pmid=19232074 |pmc=2687769 |doi=10.1186/jbiol114 |doi-access=free }}</ref> Early humans may have encountered the parasite while sleeping in quarters vacated by gorillas or by eating gorilla carcasses.<ref name="e237">{{cite web |last=Zimmer |first=Carl |date=2023-11-08 |title=Lice Genes Offer Clues to Ancient Human History |url=https://www.nytimes.com/2023/11/08/science/lice-genes-human-history.html |access-date=2025-03-17 |website=The New York Times}}</ref>
== In popular culture == "Pediculis{{Sic}} pubis" is a crude song by the Yugoslav rock band Bijelo Dugme recorded in 1984 as part of their self-titled album ''Bijelo Dugme''.<ref>{{Cite web |date=2022-05-14 |title=Kako su nastale najpopularnije pjesme (11): Pedikulis pubis (VIDEO) |url=https://srpskainfo.com/kako-su-nastale-najpopularnije-pjesme-11-pedikulis-pubis-video/ |access-date=2024-11-29 |website=Srpskainfo |language=sr}}</ref>
==References== {{Reflist}}
==External links== {{Portal|Medicine}} {{Commons category|Pubic lice}} * [https://entnemdept.ufl.edu/creatures/urban/crab_louse.htm Crab louse] on the UF / Institute of Food and Agriculture
{{STD/STI}} {{Human lice}} {{Arthropod infestations}} {{authority control}}
Category:Lice Category:Sexually transmitted infections Category:Parasitic infestations, stings, and bites of the skin