Pediculosis pubis

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Pediculosis pubis
Other namesCrabs, pubic lice, phthiriasis, phthiriasis pubis
SOA-Pediculosis-pubis.jpg
Pubic lice in genital area
Specialty Infectious disease
Symptoms Itch, scratch marks, grey-blue marks, visible lice and nits
Complications Secondary bacterial infection
Causes pubic louse
Risk factors Sexual activity, crowded situations
Diagnostic method Direct vision of lice with or without magnifying glass
Treatment
  • Application of permethrin containing lotions
  • Removing nits with comb

Pediculosis pubis (also known as "crabs" and "pubic lice") 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. [1] [2] [3] 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. [1] [4]

Contents

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. [1] [2] [3] Scratch marks, crusting and scarring may be seen, and there may be signs of secondary bacterial infection. [1]

Diagnosis is by visualising the nits or live lice, either directly or with a magnifying glass. [5] Investigations for other sexually transmitted infections (STIs) are usually performed. [6]

First line treatment usually contains permethrin and is available over the counter. [3] Two rounds of treatment at least a week apart are usually required to kill newly hatched nymphs. [5] 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. [6] Sexual partners should be evaluated and treated. [6]

Infestation with pubic lice is found in all parts of the world and occurs in all ethnic groups and all levels of society. [6] Worldwide, the condition affects about 2% of the population. [7]

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. [1] [4] [8] 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. [3] [9] [6] Louse droppings may be noticed as a black powder in the underwear. [8]

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. [1] Some people with pubic lice infestation may not have any symptoms. [9]

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. [1] [8]

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. [4] [8] [10] One sexual encounter with an infected person carries a high risk of catching pubic lice. [11] 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. [1] [8]

Infestation on the eyebrows or eyelashes of a child may indicate sexual exposure or abuse. [6]

Characteristics and life cycle

Crab lice Crab Lice CDC.png
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 two front legs are very large and look like 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. [6] 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. [4] [12]

Diagnosis

Diagnosis is made by carefully looking at the pubic hair for nits, young lice and adult lice. [4] 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). [5] A magnifying glass, dermatoscope or a stereo-microscope can be used for identification. [2] [5] Testing for other sexually transmitted infections is recommended in those who are infested with pubic lice. [4]

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. [1] [2] [3] Although the presence of pubic lice is associated with the presence of other sexually transmitted diseases, pubic lice do not spread infectious diseases. [13]

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. [2]

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. [1] [3] 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. [2] [14] Re-infestation can be prevented by wearing clean underwear at the start of treatment and after completing treatment. [2] Shaving the affected hair is not essential. [2]

First line

Nit comb Nit comb.jpg
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. [6] Brands of permethrin include 'Lyclear', available in the UK as a creme rinse or dermal cream at 5% strengths. [15] [16] In the US, common permethrin brands include NIX, Actin and Elimite. [17]

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. [14] [18] These medications are safe and effective when used exactly according to the instructions in the package or on the label. [6] To kill newly hatched lice, both treatments can be repeated within the following seven to ten days. [5] [19]

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). [2] The CDC states alternatives as topical 0.5% malathion or oral ivermectin. [14]

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. [2] 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. [2] [4] Lindane is not recommended in pregnant and breastfeeding women, children under the age of two years, and people who have extensive dermatitis. [4] [6] 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). [6] [20] 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. [2] [21]

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. [6]

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. [22] Eyelashes may be treated with a gentle petroleum jelly for occlusion. [22]

Epidemiology

Infestation with pubic lice is found in all parts of the world, occurs in all ethnic groups and all levels of society. [6]

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. [7]

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. [2] [23] [24]

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. [25] 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). [26]

Other animals

Humans are the only known hosts of this parasite, [3] although a closely related species, Pthirus gorillae , infects gorilla populations. [27]

Related Research Articles

<span class="mw-page-title-main">Scabies</span> Human disease

Scabies is a contagious human skin infestation by the tiny (0.2–0.45 mm) mite Sarcoptes scabiei, variety hominis. The word is from Latin: scabere, lit. 'to scratch'. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may appear on the skin. In a first-ever infection, the infected person usually develops symptoms within two to six weeks. During a second infection, symptoms may begin within 24 hours. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection in the skin.

<span class="mw-page-title-main">Louse</span> Order of insects

Louse is the common name for any member of the clade Phthiraptera, which contains nearly 5,000 species of wingless parasitic insects. Phthiraptera has variously been recognized as an order, infraorder, or a parvorder, as a result of developments in phylogenetic research.

<span class="mw-page-title-main">Sucking louse</span> Suborder of insects

Sucking lice have around 500 species and represent the smaller of the two traditional superfamilies of lice. As opposed to the paraphyletic chewing lice, which are now divided among three suborders, the sucking lice are monophyletic.

<span class="mw-page-title-main">Crab louse</span> Species of insect

The crab louse or pubic louse is an insect that is an obligate ectoparasite of humans, feeding exclusively on blood. The crab louse usually is found in the person's pubic hair. Although the louse cannot jump, it can also live in other areas of the body that are covered with coarse hair, such as the perianal area, the entire body, and the eyelashes.

<span class="mw-page-title-main">Pubic hair</span> Hair in the human genital area

Pubic hair is terminal body hair that is found in the genital area of adolescent and adult humans. The hair is located on and around the sex organs and sometimes at the top of the inside of the thighs. In the pubic region around the pubis bone and the mons pubis that covers it, it is known as a pubic patch. Pubic hair is also found on the scrotum and base of the penile shaft in males and on the vulva in females.

<span class="mw-page-title-main">Pediculosis</span> Medical condition

Pediculosis is an infestation of lice from the sub-order Anoplura, family Pediculidae. Accordingly, the infestation with head lice is named pediculosis capitis, while this with body lice, pediculosis corporis. Although pediculosis in humans may properly refer to lice infestation of any part of the body, the term is sometimes used loosely to refer to pediculosis capitis, the infestation of the human head with the specific head louse.

<span class="mw-page-title-main">Head louse</span> Insect parasite of humans

The head louse is an obligate ectoparasite of humans. Head lice are wingless insects that spend their entire lives on the human scalp and feed exclusively on human blood. Humans are the only known hosts of this specific parasite, while chimpanzees and bonobos host a closely related species, Pediculus schaeffi. Other species of lice infest most orders of mammals and all orders of birds.

<span class="mw-page-title-main">Treatment of human lice</span>

The treatment of human lice is the removal of head lice parasites from human hair. It has been debated and studied for centuries. However, the number of cases of human louse infestations has increased worldwide since the mid-1960s, reaching hundreds of millions annually. There is no product or method that assures 100% destruction of the eggs and hatched lice after a single treatment. However, there are a number of treatment modalities that can be employed with varying degrees of success. These methods include chemical treatments, natural products, combs, shaving, hot air, and silicone-based lotions.

<span class="mw-page-title-main">Body louse</span> Subspecies of insect

The body louse is a hematophagic ectoparasite louse that infests humans. It is one of three lice which infest humans, the other two being the head louse, and the crab louse or pubic louse.

A louse is a wingless insect.

<span class="mw-page-title-main">Head lice infestation</span> Medical condition

Head lice infestation, also known as pediculosis capitis, is the infection of the head hair and scalp by the head louse. Itching from lice bites is common. During a person's first infection, the itch may not develop for up to six weeks. If a person is infected again, symptoms may begin much more quickly. The itch may cause problems with sleeping. Generally, however, it is not a serious condition. While head lice appear to spread some other diseases in Africa, they do not appear to do so in Europe or North America.

<span class="mw-page-title-main">Sexually transmitted infection</span> Infection transmitted through human sexual behavior

A sexually transmitted infection (STI), also referred to as a sexually transmitted disease (STD) and the older term venereal disease (VD), is an infection that is spread by sexual activity, especially vaginal intercourse, anal sex, oral sex, or sometimes manual sex. STIs often do not initially cause symptoms, which results in a risk of passing the infection on to others. Symptoms and signs of STIs may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. Some STIs can cause infertility.

<span class="mw-page-title-main">No nit policy</span> Public health policy

No nit policy is a public health policy implemented by some education authorities to prevent the transmission of head lice infestation. The "no nit" policy requires the sending home and barring of all children who have nits on their hair from controlled settings such as school, summer camp or day care facilities. The CDC, American Academy of Pediatrics (AAP) and the National Association of School Nurses (NASN) advocate that "no-nit" policies should be discontinued, due in part because nits, the eggs or empty egg shells, are not transmissible and the burden of unnecessary absenteeism to the students, families and communities far outweighs the risks associated with head lice. Proponents of the no-nit policy counter that only a consistently nit-free child can be reliably shown to be infestation-free. That is, the presence of nits serves as a proxy for infestation status. Proponents argue that such a proxy is necessary because lice screening is prone to false negative conclusions.

An ectoparasitic infestation is a parasitic disease caused by organisms that live primarily on the surface of the host.

<span class="mw-page-title-main">Pediculosis corporis</span> Medical condition

Pediculosis corporis or Vagabond's disease is a cutaneous condition caused by body lice that lay their eggs on clothing and to a lesser extent on human hairs.

<i>Pthirus gorillae</i> Species of louse

Pthirus gorillae or gorilla louse is a species of parasitic sucking louse that afflicts gorillas. It is found in the African continent, specifically in Rwanda and Democratic Republic of the Congo. P. gorillae and P. pubis are the only known species that belong to the genus Pthirus, often incorrectly spelled as Phthirus. It is suggested that it is transmitted among its hosts by social grooming, shared bedding and sexual contact.

<i>Pthirus</i> Genus of lice

Pthirus is a genus of lice. There are only two extant species, and they are the sole known members of the family Pthiridae. Pthirus gorillae infests gorillas, and Pthirus pubis afflicts humans, and is commonly known as the crab louse or pubic louse. The two species diverged some 3.3 million years ago.

<i>Trichodectes canis</i> Species of louse

Trichodectes canis, also known as canine chewing louse, is a chewing louse found on domesticated dogs and wild canids throughout the world. T. canis is a well-known vector for the dog tapeworm, Dipylidium caninum. T. canis usually does not present any major problems to the host, however, can be very irritating in heavy infestations. In North America and most developed countries, T. canis infestation of domesticated dogs is very uncommon as long as they are properly cared for and healthy. Poorly taken care of dogs are more prone to getting a lice infestation.

<i>Haematopinus suis</i> Species of louse

Haematopinus suis, the hog louse, is one of the largest members of the louse suborder Anoplura, which consists of sucking lice that commonly afflict a number of mammals. H. suis is found almost solely on the skin surface of swine, and takes several blood meals a day from its host. H. suis has large claws that enable it to grasp a hog's hair and move around its body. It is easily seen without magnification, being 5–6 millimetres (0.20–0.24 in) long. H. suis has a long, narrow head and long mouthparts adapted for sucking blood. It is the only louse found on swine. H. suis infestation is relatively rare in the US; a 2004 study found that about 14% of German swine farms had H. suis infestations. Due to the frequency of feeding, infected swine become severely irritated, often rubbing themselves to the point of injuring their skin and displacing body hair. Particularly afflicted hogs may become almost completely bald and, in young hogs, the resulting stress can arrest growth, a cause of concern for farmers.

Mutual monogamy is a form of monogamy that exists when two partners agree to be sexually active with only one another. Being in a long-term mutually monogamous relationship reduces the risk of acquiring a sexually transmitted infection (STI). It is one of the most reliable ways to avoid STIs. Those who choose mutual monogamy can be tested before the sexual relationship to be certain they are not infected. This strategy for the prevention of acquiring a sexually transmitted infection requires that each partner remain faithful and does not engage in sexual activity with another partner.

References

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  24. ↑ Bloomberg: Brazilian bikini waxes make crab lice endangered species, published 13 January 2013, retrieved 14 January 2013
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