■ Pruritus and excoriations in the scalp area, nits on hairs, especially in the retroauricular area.
■ In some cases scalp dermatitis, especially at the nuchal hair line: small papules, moist exanthema, and crusting.
■ Occasionally also generalized dermatitis on other parts of the body caused by allergic reactions to louse antigens.
■ Both objective and subjective symptoms may be lacking in up to 20% of cases.
Diagnosis. Determination of symptoms and detection (direct or with magnifier) of lice and/or nits, especially around the temples, ears, and neck.
It is important to clarify the epidemiological background regarding all possible sources of infestation (e.g., in schools). Some countries have introduced regulations on control of outbreaks of louse infestation in schools and other community institutions.
Therapy. In group outbreaks, all contact persons must be treated concurrently, e.g., entire school classes and the families of infested children. A variety of different insecticides are available for therapy, for instance pyrethrum, permethrin, malathion, and y-hexachlorocyclohexane (y-HCH, lindane). (important: lice may show resistance to certain insecticides!) Follow the preparation application instructions and repeat application after seven to 10 days. Rinsing the hair with 5% vinegar in water followed by mechanical removal of the nits with a "louse comb" is a supportive measure.
Control. Clothing, pillows, etc. that have been in contact with lice must be decontaminated: wash laundry at 60 °C; keep clothes and other objects in plastic bags sealed with adhesive tape for four weeks or deep-freeze the bags for one day at -10 to -15 °C. Clean upholstered furniture, mattresses, etc. thoroughly with a vacuum cleaner and decontaminate as necessary (consult an expert for pest control).
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