SeminarScabies and pediculosis
Section snippets
Aetiology and epidemiolog
Scabies has been known for over 2500 years. It is caused by a mite, Sarcoptes scabiei var hominis, an obligate human parasite that burrows tunnels downwards into the epidermis (not deeper than the stratum granulosum). Mites of all developmental stages tunnel into the stratum corneum and deposit faeces behind them; the female also lays eggs in the tunnels. Scabies occurs in both sexes and all age-groups. Since it is transmitted by skin-to-skin contact, sexual transmission is common, as is
Topical scabicides
The choice of scabicide must be based on effectiveness and potential toxicity, extent of secondary eczematisation, and the patient's age. Panel 1 lists agents used as scabicides worldwide; the recommended drugs vary from one country to another. For most, there have been no controlled studies documenting that two applications are better than one.
Benzyl benzoate is used alone or in combination with sulfiram. Different treatment regimens have been proposed (swabbing only once, two applications
Aetiology and epidemiology
Pediculosis has been known for over 10 000 years. The oldest eggs (6900–6300 BC) were found in the Nahal Herman Cave in the Judean Desert.32 A louse egg was discovered attached to a hair of a pregnant woman buried under the ashes of Herculaneum (Aug 24, 79 AD).33
Lice are blood-sucking insects and specific parasites of human beings. Pediculus humanus var capitis lives on the head (head lice); P humanus var corporis lives in the person's clothes, benefiting from the warmth and feeding on the body
Head lice
Many agents are available. The effectiveness of combs (plastic, aluminium, thermal, and electronic) remains to be established by rigorous randomised clinical trials. Head shaving should be avoided whenever possible because it is humiliating, especially in girls.
Most treatments are sold over the counter by pharmacists. In Glasgow, Scotland, 19 000–36 000 bottles of insecticide were bought by the public in 1991. Sales of all licensed products rose 3·7-fold between 1990 and 1995 in England and
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