yi2 THE ANIMAL PARASITES OF MAN 



in, eczemas are set up at the points attacked, and these often spread 

 to the neighbouring parts not covered with hair. 



Of special interest is the onset of maculae caeruleae (taches bleues) 

 in some persons affected with crab lice (people disposed to sweating 

 seem to be peculiarly liable to these). They consist in pale blue 

 patches of various size and shape, varying from that of a hemp-seed 

 to that of a lentil, and again to that of a nail in size and form. These 

 are found over the cutaneous surface of the abdomen, thorax and 

 thigh, and are often only seen by a good lateral illumination. Duguet 1 

 considers that the condition is a toxic erythema, that it is set up, on 

 the occasion of the bite of the parasite penetrating the skin, by the 

 poisonous substance derived from it. Oppenheim 2 considers that it 

 is a colouring substance that is formed in the salivary glands of the 

 parasites, and which penetrates the skin when the insects bite, and 

 thus forms the maculae caeruleae. We have on several occasions 

 emulated the experiment of Duguet (trituration in a mortar of crab 

 lice freshly taken from the human body and inoculating the mass 

 thus obtained beneath the skin), and have similarly been enabled to 

 produce the maculae caeruleae experimentally, but we have certainly 

 been unable to determine which of the hypotheses is the correct 

 one, the toxic erythema or the colouring substance inhibition 

 theory. 



The diagnosis of phthirasis is very easy, for either the sexually 

 mature parasites or the nits are found on the hairs. 



As regards treatment, grey ointment is regarded as a generally 

 useful application ; it gives rise, however, to a slight eczema of the 

 genitals, espejially in males, when injudiciously used. Geber 3 

 recommends petroleum or balsam of Peru, Oppenheim 4 a i per cent, 

 sublimate solution for lotions, or a mixture of equal parts of petroleum 

 and benzine when the sublimate cannot be borne. The use of 

 a 5 per cent, ointment with hydrarg. oxid. flavum is worth consider- 

 ing in treatment of pediculosis of the eyebrows and eyelashes. The 

 simplest method of treatment, and one with a radical effect, is that by 

 sulphuric ether recommended by Thomer. 5 It certainly produces 

 a sharp burning sensation, but the living parasites and nits are 

 destroyed in one sitting. We prefer ether lotions as a rule, and we 

 thoroughly rub the affected parts with a pad of wadding well soaked 

 with the ether. The dead parasites and the nits fall on to what lies 



1 Duguet, AnnaL de Derm., II Ser., i. 



- Oppenheim, "Handb. d. Hauikrankh.," v. Mracek, 1907. 



3 Geber, see Seifert, Lesser's " Encyclop.," p. 387. 



4 Oppenheim, loc. cit. 



5 Thomer, see Seifert, Lesser's " Encyclop.," p. 387. 



