710 THE ANIMAL PARASITES OF MAN 



boys. In families it is endemic, in schools epidemic, but it also 

 occurs in fair frequency in female adults (servant maids, waitresses) 

 who may pay little attention to bodily cleanliness. The puncture 

 of the parasites sets up a severe irritation, which leads to violent 

 scratching. The consequences of this are the formation of nodules 

 and pustules, crusts and "weeping " patches; the hairs become felted 

 and the final clinical picture is that of plica polonica. The conditions 

 of irritation which are produced by these parasites and then by the 

 scratchings of the impetiginous, and frequently the very severe 

 suppurative processes of the hair-bed, lead to swellings in the neck 

 and sometimes even to glandular suppurations. The eczematous 

 processes not infrequently extend over the face, the neck and the 

 thorax. Blepharitis and conjunctivitis may be due to Pediculus 

 capitis. 



The means of infection are often very remarkable. Transmission 

 from one individual to another certainly often occurs, but infection 

 may take place in railway carriages and in other ways. A case under 

 the observation of a colleague in Frankfort is a most remarkable one : 

 he diagnosed pediculosis as the cause of a head eczema occurring 

 among the children of one of the best families there. The infection 

 took place through dolls adorned with human hair, in which the 

 presence of nits could be demonstrated. 



The diagnosis of Pediculus capitis is not difficult to make when 

 the hairs and hairy scalp are carefully examined for nits and living 

 parasites. In better families it is a good plan to point out the 

 corpora delicti to their possessors and to make them aware of the 

 possible sources of infection. 



As regards treatment, lotions of sabadill vinegar are recom- 

 mended ; in slighter cases these are^ quite sufficient. In severe cases 

 cure will not result unless dressings of petroleum, naphthol ointment 

 (5 to 10 per cent.) and balsam of Peru be applied. In the case of 

 plica polonica, the hair must be cut quite short (even in adults) so 

 as to control matting of the hair. To get rid of nits from hair that 

 is not matted, careful combing and washing with strongly alkaline 

 fluids or with hot vinegar is suitable. 



Pediculus vestimenti (Clothes Louse). 



The clothes louse attacks adults by preference, and with especial 

 frequency old and emaciated persons. It lives in the clothes, but 

 derives its nourishment from the body. At the moment at which 

 the clothes louse inserts its proboscis into the skin the person experi- 

 ences a slight sting, which, however, at once ceases to hurt. If the 

 body of the louse is sucked full of blood it falls off and the individual 



