Pediculosis - louse, lice infestation
Pediculosis — louse infestation — can be traced to prehistory, with the oldest known fossils of louse eggs dating back approximately 10,000 years
Lice are ectoparasites that live on the body, feeding on blood after piercing the skin and injecting saliva, which causes pruritus. The three types of human lice are:
• Head lice — Pediculosis capitis
• Body lice — Pediculosis corporis
• Pubic or crab lice — Pediculosis pubis or Pthirus pubis
The head louse(Pediculosis capitis) has an elongated body and narrow anterior mouthparts, and lays eggs at the base of hair fibres. Body lice (Pediculosis corporis) look similar but are larger and lay their eggs on clothing fibres, particularly in fabric seams. The pubic louse (Pediculosis pubis) has a wide, crab-like, body and also lays eggs at the base of hair fibres.
The body louse is a vector of typhus, trench fever, and relapsing fever.
Of the three species, head lice are the most common and the majority of infestations involve between 10 and 20 adult lice. An adult head louse measures 2-3mm, is wingless, white to grey in colour and has three pairs of clawed legs. A mature female louse lays 3-6 white eggs a day, each less than 1 mm long. These hatch in around 7 days, with the lice reaching maturity in 12-15 days, and living as adults for about another 10. Empty egg shells are called nits.
Head lice spread from person to person only by head-to-head contact. Detecting live head lice is difficult as nymphs and mature lice can move rapidly through dry hair, so diagnosis often rests on identifying the presence of eggs or nits. There is a wide range of treatment options, the majority of which include the use of specialised head lice detection and removal combs.
Louse infestation remains a major problem worldwide. The incidence of pediculosis has risen steadily in the United States over the last three decades, and head lice infestation among school children has reached epidemic proportions in many parts of the US and Australia. As the incidence grows, so too does the importance of regular diagnosis and treatment including the use of specialist head lice combs for effective detection and removal.
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