Head Lice (Pediculosis)
Pediculosis is an infestation of lice -- blood-feeding ectoparasitic insects of the order Phthiraptera.[1][2] The condition can occur in almost any species of warm-blooded animal (i.e., mammals and birds), including humans.[1][2] 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.
Classification
Pediculosis may be divided into the following types:[3]:446-8
- Pediculosis capitis
- Pediculosis corporis (Pediculosis vestimenti, Vagabond's disease)
- Pediculosis pubis (Crabs)
Pediculosis due to human head lice
Presentation
- Head-louse infestation is most frequent on children aged 3-10 and their families. Approximately 3% of school children in the United States contract head lice.[4]
- Females get head lice more often than males, and infestation in the black ethinicity is rare.[5]
- 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.[4]
- Lice cannot burrow into the skin.
Diagnosis and symptoms
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.[6]
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.
Treatment and prevention
Main article: Treatment of human head lice
The number of diagnosed cases of human louse infestations (or pediculosis) has increased worldwide since the mid-1960s, reaching hundreds of millions annually.[7] 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.
Examination of the child’s head at regular intervals using a louse comb allows the diagnosis of louse infestation at an early stage. Early diagnosis makes treatment easier and reduces the possibility of infesting others. In times and areas when louse infestations are common, weekly examinations of children, especially those 4–13 yrs old, carried out by their parents will aid control.