Diagnosis of an infestation is normally by a report by the victim or clinical observation of the symptoms. Doctors may perform a microscopic examination of the lice and nits for confirmation of the diagnosis.
Treatments for infestation of P. pubis include taking a shower and then applying a 1% gamma benzene hexachloride ointment or lotion. This is normally left on for 12 hours. Eyelash infestations are treated with white petrolatum ointment for 10 days. Clothing and bedding can be laundered in boiling water or dry cleaned and items inconvenient to clean should be stored away from other bedding and clothing for a month. Without blood, the lice will soon die.
Presumably, lice can tell when they have hit a blood vessel when beginning to feed by sensing chemicals released at the site of the wound. Also, lice have short antennae with chemoreceptors and tactile hairs, and some, such as P. pubis, have simple eyes. No information is available on how these lice communicate with one another.
Perception Channels: visual ; tactile ; chemical
All lice exhibit hemimetabolous development, consisting of three life stages: egg, nymph, and adult. The eggs of P. pubis hatch in six to eight days and the young lice then pass through three nymphal stages, lasting a total of 23 days, before becoming adults.
Development - Life Cycle: metamorphosis
Infestation of P. pubis is a sexually transmitted condition causing serious itching to its victims. Irritation is increased in the area with host scratching and the area can often become scabby with oozing lesions. Asymptomatic individuals may discover nits or lice on pubic hair, or black specks on underpants. Characteristic small blue-gray macules known as maculae caeruleae may appear at bitten sites. Complications including excoriations, secondary bacterial infections, and eczematization may ensue.
Pthirus pubis thrives in unsanitary, overcrowded living conditions and historically has been common in military, refugee, and concentration camps, prisons, and overcrowded city dwellings. Overcrowding favors P. pubis because it can migrate between hosts easily and is not always contracted through sexual contact.
Unlike body lice (Pediculus humanus), pubic lice are not known to spread typhus.
Negative Impacts: injures humans (bites or stings)
There is often a strong correlation between the infection of Pthirus pubis in the eyelashes and individuals having other sexually transmitted diseases. Therefore, Pthirus pubis can sometimes be used as an indicator of more serious problems.
Pthirus pubis is an obligate ectoparasite of humans.
Ecosystem Impact: parasite
Species Used as Host:
Pubic lice feed on human blood and will die within 24 hours without having a human blood meal. Species in the order Anoplura, to which P. pubis belongs, have a highly modified feeding mechanism. They lack mandibles like all other types of lice and they have a fascicle made of four stylets which they use to feed on the blood of their hosts. The haustellum derived from the labrum supports the fascicle. Two of the stylets derived from the maxillae lock together to form a food channel. A single hollow stylet derived from the hypopharynx connects with the salivary duct and conveys salivary materials into the wound. And a large flattened stylet derived form the labium cuts into tissue with a serrated tip and serves as a guide for the other stylets. The cibarium and pharynx in the head serve as a two-chambered pump, sucking material in through the mouth and passing it on to the esophagus.
Animal Foods: blood
Primary Diet: carnivore (Sanguivore )
Pthirus pubis is a host specific louse found throughout the world on humans.
Biogeographic Regions: nearctic ; palearctic ; oriental ; ethiopian ; neotropical ; australian ; oceanic islands
Other Geographic Terms: cosmopolitan
Pthirus pubis lays its eggs on coarse body hair, especially in hair associated with the pubic regions, but also in the anal region, armpits, thighs, abdomen and will even infect eyelashes and beards. These regions have flattened hairs, which the claws of P. pubis are highly modified to grasp. These lice are mostly found in unsanitary or overcrowded conditions of human hosts.
Habitat Regions: temperate ; tropical ; polar ; terrestrial
Other Habitat Features: urban ; suburban ; agricultural
These lice normally live for a little less than a month, dying soon after reproducing. However, when separated from a host, they live less than 24 hours.
Average lifespan
Status: wild: 1 months.
Smaller than Pediculus humanus (head and body lice), gray "crab" lice are 1.25 to 2 mm long. Pthirus pubis has an oval body shape and is wider than it is long and these lice are given the nickname "crabs" from their shape and chelate tarsi. These lice also have small heads relative to their body size, simple eyes, and short antennae. The lice have six legs, each of which terminate with a tarsal claw. The claws on the 2nd and 3rd pairs of legs are huge compared to those on the pair of legs closest to the head, which are smaller and thinner. Pthirus pubis also has another modification of the claw region, which is actually an extension of the tibia, called the thumb of the tibia which allows it to grasp the flattened hairs of the pubic region of humans. Another distinguishing feature is the four pairs of tubercles, which stick out on each side of the animal's abdomen. Lice breathe through spiracles at the ends of these para-tergal sclerites leading to the tracheal system.
Range length: 1.25 to 2 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
No information is available on the mating system of these lice.
These lice reach sexual maturity about 23 days after hatching from eggs. Reproduction is sexual, with the male P. pubis inserting his aedeagus (male reproductive intromittant organ) into the female genital opening and deposting sperm. Females lay approximately 30 eggs in a lifetime and when cemented to hairs, these are called nits.
Breeding season: These lice breed year-round.
Range gestation period: 6 to 8 days.
Average age at sexual or reproductive maturity (female): 23 days.
Average age at sexual or reproductive maturity (male): 23 days.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Female lice provide nutrients to their eggs before laying them and then abandon them.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female)
The Pubic (or Crab) Louse (Pthirus pubis, often incorrectly spelled Phthirus pubis) is an insect in the Order Psocodea (parasitic lice, formerly Order Phthiraptera, plus bark lice, formerly Order Psocoptera). Pubic Lice are ectoparasites with humans as the only host.They are found throughout the world.
Pubic lice 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. Adults are found only on the human host and require human blood 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.
The crab louse or pubic louse (Pthirus pubis) is an insect that is an obligate ectoparasite of humans, feeding exclusively on blood.[1] 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 (in men), and the eyelashes (in children).[2][3]
Humans are the only known hosts of the crab louse, although a closely related species, Pthirus gorillae, infects gorillas. The human parasite is thought to have diverged from Pthirus gorillae approximately 3.3 million years ago.[4] It is more distantly related to the genus Pediculus, which contains the human head and body lice and lice that affect chimpanzees and bonobos.
An adult crab louse is about 1.3–2 mm long (slightly smaller than the body louse and head louse), and can be distinguished from those other species by its almost round body. Another distinguishing feature is that the second and third pairs of legs of a crab louse are much thicker than the front legs and have large claws.[5]
The eggs of the crab louse are laid usually on the coarse hairs of the genital and perianal regions of the human body. The female lays about three eggs a day. The eggs take 6–8 days to hatch, and there are three nymphal stages which together take 10–17 days before the adult develops, making a total life cycle from egg to adult of 16–25 days. Adults live for up to 30 days.[5] Crab lice feed exclusively on blood, and take a blood meal 4–5 times daily. Outside the host they can survive for 24–48 hours. Crab lice are transmitted from person to person most commonly via sexual contact, although fomites (bedding, clothing) may play a minor role in their transmission.[6]
Infestation of the eyelashes is referred to as pediculosis ciliaris or phthiriasis palpebrarum.[7]
The main symptom of infestation with crab lice is itching, 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 appears (maculae caeruleae) at the feeding site, which may last for several days.
Current worldwide prevalence has been estimated at 2% of the human population, but accurate numbers are difficult to gauge because crab louse infestations are not considered a reportable condition by many health authorities, and many cases are self-treated or treated discreetly by physicians.[8]
It has been suggested that an increasing percentage of humans removing their pubic hair, especially in women, has led to reduced crab louse populations in some parts of the world.[9][10]
Crab lice are not known to transmit disease. In infested individuals an average of a dozen lice can be found. Although they are typically found attached to hair in the pubic area, sometimes they are also found on coarse hair elsewhere on the body (for example, eyebrows, eyelashes, beard, moustache, chest, armpits, etc.). They do not generally occur on the finer hair of the scalp.[5][11] Crab lice attach to pubic hair that is thicker than other body hair because their claws are adapted to the specific diameter of pubic hair and other thick hairs of the body.[12] Crab louse infestations (pthiriasis) are usually spread through sexual contact and are most common in adults.[12][2][3] The crab louse can travel up to 25 cm (10 in) on the body. Crab louse infestation is found worldwide and occurs in all races and ethnic groups and in all socio-economic levels. Occasionally they may be also transmitted by close personal contact or contact with articles such as clothing, bed linen, and towels that have been used by an infested person.[6][13]
Crab lice found on the head or eyelashes of children may be an indication of sexual exposure or abuse.[14] Symptoms of crab louse infestation in the pubic area include itching, redness and inflammation. Crab lice are not known to transmit disease; however, secondary bacterial infection can occur from scratching of the skin.
Crab louse infestation can be diagnosed by identifying the presence of active stages of the louse, as well as of eggs (nits) on the pubic hair and other hairs of the body. When infestation is diagnosed, other family members and contact persons should also be examined. A magnifying glass or dermoscope could be used for better identification.[12]
This article incorporates text from this source, which is in the public domain. This article incorporates text from this source, which is in the public domain. This article incorporates text from this source, which is in the public domain. This article incorporates text from this source, which is in the public domain. The crab louse or pubic louse (Pthirus pubis) 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 (in men), and the eyelashes (in children).
Humans are the only known hosts of the crab louse, although a closely related species, Pthirus gorillae, infects gorillas. The human parasite is thought to have diverged from Pthirus gorillae approximately 3.3 million years ago. It is more distantly related to the genus Pediculus, which contains the human head and body lice and lice that affect chimpanzees and bonobos.
