From Wikipedia, the free encyclopedia
Pediculosis 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 (i.e., mammals and birds), including humans. 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.
Pediculosis may be divided into the following types::446-8
Pediculosis capitis (Head lice infestation)
Pediculosis corporis (Pediculosis vestimenti, Vagabond's disease)
Pediculosis pubis (Crabs)
Main article: Pediculosis capitis
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
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.
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
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.
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
The United Kingdom's National Health Service, and many American health
agencies , 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).
Main article: Pediculosis corporis
This condition, is caused by body louse (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.
Main article: Pediculosis pubis
The pubic or crab louse (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
louse[Damalinia (Bovicola) bovis], the shortnosed cattle louse (Haematopinus
eurysternus), the longnosed cattle louse (Linognathus vituli), and the little blue
cattle louse (Solenopotes capillatus).
Cattle infested with bovine pediculosis are generally treated chemically, by drugs
like ivermectin and cypermethrin.