(Head-lice; Head-lousiness; Phthiriasis capitis)
Head-lice produce no direct lesion, but the itching they excite cause such extensive excoriations that the eruption may become eczematous and show papules, vesicles, pustules, furuncles and abscesses. The occipital region, where the hair is thickest, is the favoirte seat and there marked crusting, pustular formations are found. The exudation of serum of pus, mingling with dust, scales and crusts may mat the hair to a pronounced degree (plica polonica). Pediculi may invade any or all parts of the the hairy scalp but never go beyond its limits, although eczematous lesions may be found outside the hair border. There is marked adenitis in cases of long duration but in the healthy or vigorous the condition may be so near normal that a few pediculi cause little disturbance beyond a slight itching. In some cases the live pediculi are hard to find but the ova or nits will be found as pin-head-sized, pear-shaped, whitish or grayish bodies, firmly glued to one side of the hair. When the pediculi are few in number, only one egg may be found on the hair, but as they multiply several will be seen at intervals on one shaft. The lice appear as small grayish bodies to the naked eye and on being disturbed move with great rapidity.
Etiology and Pathology. Uncleanliness, together with habitual lack f brushing and combing the hair predisposes to pediculosis of the scalp, which is usually conveyed through the medium of infested hats, caps, combs, pillow, etc. It is more common in the poor and neglected, in children than adults, and in girls than in boys. This disease is due to an invasion of the scalp by the pediculus capitis, or headlouse. The female outranks the male in size and number and is very prolific, laying upward of fifty eggs which hatch out in one week, and fully develop in one week more. Hence a single pregnant female unmolested might give origin to a family of five thousand in eight weeks.
Diagnosis. This may be made positive by discovery of the pediculi or their ova but any itching pustular eruption of the occiput is suspicions.
Treatment is causal and is aimed to kill the pediculi, devitalize the ova. And cure the resultant dermatitis.
In young children it is well to cut the hair, but this is not necessary with older children or with women. In public practice it is my custom to saturate the scalp for two or three nights with kerosene oil; the patient wearing a closely fitting cap, and care being taken not to allow the oil to run down and irritate the adjacent skin. The danger of setting on fire such an oil-soaked head should be remembered. Other prescriptions which kill the pediculi and sterilize the nits are as follows: ammoniated mercury, sulphur or betanaphthol, from 20 to 60 grains to the ounce of petrolatum; balsam Peru 1 ounce to 4 each of vaseline and olive oil; or carbolic acid 15 to 25 grains to the ounce of vaseline. Creolin, corrosive sublimate or sulphur-naphthol soaps may be used in the daily shampoo.
In the case of adults soap and water or tincture of green soap may be used a shampoo and a solution substituted for the ointment, such as fluid extract of staphisagria, crude petroleum, tincture of cocculus indicus 1 part to 3 of water, or mercuric chlorid 1 or 2 grains to the ounce. To remove the dead nits ordinary vinegar, dilute acetic acid, or I per cent. potassium hydroxid solution should be frequently applied, together with me combing.