Pediculosis
Encyclopedia
Pediculosis is an infestation of lice — blood-feeding ectoparasitic insect
s of the order Phthiraptera. The condition can occur in almost any species of warm-blooded animal (i.e., mammal
s and bird
s), including human
s. 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
.
Females are more frequently infested than males. Those of African descent rarely suffer infestation due to differences in hair texture.
Head lice are spread through direct head-to-head contact with an infested person. From each egg or "nit" may hatch one nymph that will grow and develop to the adult louse.
Lice feed on blood once or more often each day by piercing the skin with their tiny needle-like mouthparts. While feeding they excrete saliva, which irritates the skin and causes itching.
Lice cannot burrow into the skin.
The most characteristic symptom of infestation is pruritus (itching) on the head which normally intensifies 3 to 4 weeks after the initial infestation. The bite reaction is very mild and it can be rarely seen between the hairs.
The most common symptom of lice infestation is itching. Excessive scratching of the infested areas can cause sores, which may become infected. In addition, body lice can be a vector for louse-borne typhus, louse-borne relapsing fever or trench fever
.
Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.
The United Kingdom's National Health Service, and many American health agencies http://www.nyc.gov/html/doh/html/cd/cdped.shtmlhttp://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=186&PrintPage=1http://www.worsleyschool.net/science/files/lice/page.html, report that lice "prefer" clean hair, because it's easier to attach eggs and to cling to the strands.
Head lice (Pediculus humanus capitis) are not known to be vectors of diseases, unlike body lice (Pediculus humanus humanus), which are known vectors of epidemic or louse-borne typhus (Rickettsia prowazeki), trench fever (Rochalimaea quintana) and louse-borne relapsing fever (Borrellia recurrentis).
(Pediculus humanus humanus, sometimes called Pediculus humanus corporis) is a louse
which infests humans and is adapted to lay eggs in clothing, rather than at the base of hairs, and is thus of recent evolutionary origin. Pediculosis is a more serious threat due to possible contagion of diseases such as typhus
. Epidemiology and treatment of human body lice is described in the article on body lice.
(Pthirus pubis) is a parasitic insect which spends its entire life on human hair and feeds exclusively on blood. Humans are the only known host of this parasite, although it is more closely related to the louse parasites in other primate species, than are human head or body lice which probably evolved from it as the "original" louse infestation of humans. Epidemiology and treatment of pubic lice is discussed in the article on pubic lice.
[ Damalinia (Bovicola) bovis] , the shortnosed cattle louse (Haematopinus eurysternus), the longnosed cattle louse (Linognathus vituli), and the little blue cattle louse (Solenopotes capillatus).
.
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...
s of the order Phthiraptera. The condition can occur in almost any species of warm-blooded animal (i.e., mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s and bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s), including human
Human
Humans are the only living species in the Homo genus...
s. 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
Head louse
The head louse is an obligate ectoparasite of humans. Head lice are wingless insects spending their entire life on human scalp and feeding exclusively on human blood...
.
Classification
Pediculosis may be divided into the following types:- Pediculosis capitis (Head lice infestation)
- Pediculosis corporisPediculosis corporisPediculosis corporis is a cutaneous condition caused by body lice that lay their eggs in the seams of clothing.- See also :* Pediculosis* Skin lesion...
(Pediculosis vestimenti, Vagabond's disease) - Pediculosis pubisPediculosis pubisPediculosis 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 eyelashes causing pediculosis ciliaris. Infestation usually lead to intense itching in the pubic area...
(Crabs)
Presentation
Head-lice infestation is most frequent on children aged 3–10 and their families. Approximately 3% of school children in the United States contract head lice.Females are more frequently infested than males. Those of African descent rarely suffer infestation due to differences in hair texture.
Head lice are spread through direct head-to-head contact with an infested person. From each egg or "nit" may hatch one nymph that will grow and develop to the adult louse.
Lice feed on blood once or more often each day by piercing the skin with their tiny needle-like mouthparts. While feeding they excrete saliva, which irritates the skin and causes itching.
Lice cannot burrow into the skin.
Diagnosis
To diagnose infestation, the entire scalp should be combed thoroughly with a louse comb and the teeth of the comb should be examined for the presence of living lice after each time the comb passes through the hair. The use of a louse comb is the most effective way to detect living lice.The most characteristic symptom of infestation is pruritus (itching) on the head which normally intensifies 3 to 4 weeks after the initial infestation. The bite reaction is very mild and it can be rarely seen between the hairs.
The most common symptom of lice infestation is itching. Excessive scratching of the infested areas can cause sores, which may become infected. In addition, body lice can be a vector for louse-borne typhus, louse-borne relapsing fever or trench fever
Trench fever
Trench fever is a moderately serious disease transmitted by body lice. It infected armies in Flanders, France, Poland, Galicia, Italy, Salonika, Macedonia, Mesopotamia, and Egypt in World War I Trench fever (also known as "Five day fever", "Quintan fever" (febris Quintana in Latin), "Urban trench...
.
Treatment
The number of diagnosed cases of human louse infestations (or pediculosis) has increased worldwide since the mid-1960s, reaching hundreds of millions annually. There is no product or method which 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.Epidemiology
About 6-12 million people, mainly children, are treated annually for head lice in the United States alone. High levels of louse infestations have also been reported from all over the world including Denmark, Sweden, U.K., France and Australia.Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent child interactions more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head-to-head contact is by far the most common route of lice transmission.
The United Kingdom's National Health Service, and many American health agencies http://www.nyc.gov/html/doh/html/cd/cdped.shtmlhttp://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=186&PrintPage=1http://www.worsleyschool.net/science/files/lice/page.html, report that lice "prefer" clean hair, because it's easier to attach eggs and to cling to the strands.
Head lice (Pediculus humanus capitis) are not known to be vectors of diseases, unlike body lice (Pediculus humanus humanus), which are known vectors of epidemic or louse-borne typhus (Rickettsia prowazeki), trench fever (Rochalimaea quintana) and louse-borne relapsing fever (Borrellia recurrentis).
Body lice
This condition, is caused by body louseBody louse
The body louse is a louse which infests humans. The condition of being infested with head lice, body lice, or pubic lice is known as pediculosis.-Origins:...
(Pediculus humanus humanus, sometimes called Pediculus humanus corporis) is a louse
Louse
Lice is the common name for over 3,000 species of wingless insects of the order Phthiraptera; three of which are classified as human disease agents...
which infests humans and is adapted to lay eggs in clothing, rather than at the base of hairs, and is thus of recent evolutionary origin. Pediculosis is a more serious threat due to possible contagion of diseases such as typhus
Typhus
Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters...
. Epidemiology and treatment of human body lice is described in the article on body lice.
Pubic lice
The pubic or crab louseCrab 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...
(Pthirus pubis) is a parasitic insect which spends its entire life on human hair and feeds exclusively on blood. Humans are the only known host of this parasite, although it is more closely related to the louse parasites in other primate species, than are human head or body lice which probably evolved from it as the "original" louse infestation of humans. Epidemiology and treatment of pubic lice is discussed in the article on pubic lice.
In other animals
Pediculosis is more common in cattle than any other type of domesticated animal. This is a significant problem, as it can cause weight loss of 55 to 75 pounds per animal. Some species of lice infesting cattle include the cattle biting louseTreatment
Cattle infested with bovine pediculosis are generally treated chemically, by drugs like ivermectin and cypermethrinCypermethrin
Cypermethrin is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as in consumer products for domestic purposes. It behaves as a fast-acting neurotoxin in insects. It is easily degraded on soil and plants but can be effective for weeks when...
.
External links
- Head Lice Information, Harvard School of Public Health
- National Pediculosis Association
- Pediculus humanus facts, life cycle and head lice treatment overview at MetaPathogen