Pediculosis pubis
Encyclopedia
Pediculosis pubis is a disease caused by the crab louse
Phthirus pubis, a parasitic
insect
notorious for infesting human pubic hair
. The species may also live on other areas with hair, including the eyelash
es causing pediculosis ciliaris. Infestation usually lead to intense itching in the pubic area. Treatment with topic agents such as permethrin
or pyrethrins with piperonyl butoxide
is exceedingly effective. Worldwide it affects about 2% of the population.
ing, usually in the pubic-hair area, resulting from hypersensitivity
to louse saliva, which can become stronger over two or more weeks following initial infestation. 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 also be visible to the unaided eye.
Pubic lice are primarily spread through sweat, body contact, or sexual contact. 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. Because of the strong association between the presence of pubic lice and classic sexually transmitted infections (STIs), patients diagnosed with pubic lice should undergo evaluation for other STIs.
Infection in a young child or teenager is not necessarily indicative of sexual abuse, although this possibility should be kept in mind.
s, nymphs
, and adult lice. 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). A magnifying glass or a stereo-microscope can be used for the exact identification. If lice are detected in one family member, the entire family needs to be checked and only those who are infested with living lice should be treated.
Testing for other sexually transmitted infections is recommended in those who are affected.
agents permethrin
or pyrethrins with piperonyl butoxide
. Lindane
is a second line treatment due to concerns of toxicity. The Centers for Disease Control and Prevention
(CDC) states that lindane should not be used by persons who have extensive dermatitis
, women who are pregnant or lactating or children aged under two years. The FDA similarly warns against use in patients 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).
Bedding and clothing should be laundered and sexual contact should be avoided until cured. A second treatment is occasionally required if not improved after 3 to 7 days.
applied twice daily for 10 days or malathion
, phenothrin
and carbaryl
.
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.
s are the only known hosts of this parasite, although a closely related species, Pthirus gorillae
, infects gorilla
populations.
Crab louse
Crab lice are parasitic insects notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes. They feed exclusively on blood...
Phthirus pubis, a parasitic
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
notorious for infesting human pubic hair
Pubic hair
Pubic hair is hair in the frontal genital area, the crotch, and sometimes at the top of the inside of the legs; these areas form the pubic region....
. The species may also live on other areas with hair, including the eyelash
Eyelash
An eyelash or simply lash is one of the hairs that grow at the edge of the eyelid. Eyelashes protect the eye from debris and perform some of the same function as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object is near...
es causing pediculosis ciliaris. Infestation usually lead to intense itching in the pubic area. Treatment with topic agents such as permethrin
Permethrin
Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to...
or pyrethrins with piperonyl butoxide
Piperonyl butoxide
Piperonyl butoxide is an organic compound used as pesticide synergist, especially for pyrethroids and rotenone. It does not by itself have pesticidal properties. However, when added to insecticide mixtures, typically pyrethrin, pyrethroid, and carbamate insecticides, their potency is increased...
is exceedingly effective. Worldwide it affects about 2% of the population.
Classification
Infestation with pubic lice is called phthiriasis pubis, while infestation of eyelashes with pubic lice is called phthiriasis palpebrarum.Signs and symptoms
The main symptom is itchItch
Itch is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience. Modern science has shown that itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response...
ing, usually in the pubic-hair area, resulting from hypersensitivity
Hypersensitivity
Hypersensitivity refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification...
to louse saliva, which can become stronger over two or more weeks following initial infestation. 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 also be visible to the unaided eye.
Transmission
Pubic lice are usually acquired by intimate contact between individuals. 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.Pubic lice are primarily spread through sweat, body contact, or sexual contact. 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. Because of the strong association between the presence of pubic lice and classic sexually transmitted infections (STIs), patients diagnosed with pubic lice should undergo evaluation for other STIs.
Infection in a young child or teenager is not necessarily indicative of sexual abuse, although this possibility should be kept in mind.
Diagnosis
A pubic louse infestation is usually diagnosed by carefully examining pubic hair for nitNit
* The egg of a louse* Head lice * A trivial detail; the object of nitpicking* Nit , a unit of luminance equivalent to one candela per square metre...
s, nymphs
Nymph (biology)
In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...
, and adult lice. 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). A magnifying glass or a stereo-microscope can be used for the exact identification. If lice are detected in one family member, the entire family needs to be checked and only those who are infested with living lice should be treated.
Testing for other sexually transmitted infections is recommended in those who are affected.
Pediculosis pubis
Recommended treatments include the topicalTopical
In medicine, a topical medication is applied to body surfaces such as the skin or mucous membranes such as the vagina, anus, throat, eyes and ears.Many topical medications are epicutaneous, meaning that they are applied directly to the skin...
agents permethrin
Permethrin
Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to...
or pyrethrins with piperonyl butoxide
Piperonyl butoxide
Piperonyl butoxide is an organic compound used as pesticide synergist, especially for pyrethroids and rotenone. It does not by itself have pesticidal properties. However, when added to insecticide mixtures, typically pyrethrin, pyrethroid, and carbamate insecticides, their potency is increased...
. Lindane
Lindane
Lindane, also known as gamma-hexachlorocyclohexane, , gammaxene, Gammallin and erroneously known as benzene hexachloride , is an organochlorine chemical variant of hexachlorocyclohexane that has been used both as an agricultural insecticide and as a pharmaceutical treatment for lice and...
is a second line treatment due to concerns of toxicity. The Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
(CDC) states that lindane should not be used by persons who have extensive dermatitis
Dermatitis
-Etymology:Dermatitis derives from Greek derma "skin" + -itis "inflammation" and genetic disorder.-Terminology:There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may describe eczema, which is also called...
, women who are pregnant or lactating or children aged under two years. The FDA similarly warns against use in patients 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
Psoriasis
Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. However, psoriasis has been linked to an increased risk of...
) and in those who weigh less than 110 lbs (50 kg).
Bedding and clothing should be laundered and sexual contact should be avoided until cured. A second treatment is occasionally required if not improved after 3 to 7 days.
Pediculosis ciliaris
Infections of the eyelashes may be treated with either petroleum jellyPetroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...
applied twice daily for 10 days or malathion
Malathion
Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity, however one recent study has shown that children with higher levels of organophosphate pesticide metabolites in their urine are more likely...
, phenothrin
Phenothrin
Phenothrin, also called sumithrin, is a synthetic pyrethroid that kills adult fleas and ticks. It has also been used to kill head lice in humans...
and carbaryl
Carbaryl
Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...
.
Epidemiology
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, and many cases are self-treated or treated discreetly by personal physicians.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.
In other animals
HumanHuman
Humans are the only living species in the Homo genus...
s are the only known hosts of this parasite, although a closely related species, Pthirus gorillae
Pthirus gorillae
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...
, infects gorilla
Gorilla
Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies...
populations.
See also
- Crab louseCrab louseCrab lice are parasitic insects notorious for infesting human pubic hair. The species may also live on other areas with hair, including the eyelashes. They feed exclusively on blood...
- PediculosisPediculosisPediculosis is an infestation of lice — blood-feeding ectoparasitic insects of the order Phthiraptera. The condition can occur in almost any species of warm-blooded animal , including humans...
- List of parasites (human)
- List of cutaneous conditions
External links
- crab louse on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
Featured Creatures Web site - Edinburgh Royal Infirmary on Pubic Lice
- Medline Plus article
- Guideline on the Management of Phthirus pubis infestation (UK, 2007)
- Genetic Analysis of Lice Supports Direct Contact Between Modern and Archaic Humans