708 THE ANIMAL PARASITES OF MAN 



To give an account in detail of the drugs and methods old and 

 new used in the treatment of scabies would far outrun the limits of 

 this work. 



Demodex folliculorum. 



It is not yet certain whether the Demodex folliculorum is capable 

 of developing pathological conditions in man. Veiel 1 assumes that 

 the hair follicle mite has no connection either with the formation 

 of comedones or even with sebaceous gland disease. Kaposi 2 con- 

 siders that they cause no disease in man and cannot be regarded as 

 a cause of acne. Saalfeld 3 clearly adheres to the same standpoint, 

 similarly so Jessner, 4 who, when discussing comedones, makes no 

 mention of acne of hair follicle mites. Weyl 5 and Geber 6 adhere to 

 the opinion that the presence of a Demodex in man in contradis- 

 tinction to its presence in animals possesses absolutely no pathogenic 

 influence. On the other hand de Amicis, 7 Majochi, 8 and Dubreuilh (> 

 report single cases of pronounced circumscribed clear brown 

 pigmentations which they attribute to Demodex folliculorum. In all 

 these cases, moreover, as regards localization the affection had a 

 certain resemblance to pityriasis versicolor ; nevertheless, in the scales 

 separated off with the scalpel no fungi were found, but on the other 

 hand Demodices in moderate quantity. In his earlier cases Majochi 

 has seen the Demodex in the secretion from meibomian glands and 

 had claimed it to be the excitant of chalazion and, as Mibelli 10 did,. 

 considered it to be the cause of some diseases of the eyelids. Ivers 11 

 found the parasite in 69 per cent, of normal borders of the eyelids, 

 and attributes a pathological signification to it. Hiinsche 12 and 

 Mulder 13 arrive at the same conclusions ; in the light of their investiga- 

 tions the Demodex is found as a constant accessory certainly not in 

 the meibomian glands, as it is limited only to the internal part of the 

 hair follicle. Lewandowsky 14 considers that it can hardly be demon- 

 strated at present that the same parasite which in individual specimens 

 causes no symptoms is capable of producing pathological conditions 

 when markedly increased in numbers. 



Treatment is by the removal of the comedones, above all, by their 

 mechanical removal by pressure with a watch-key and with the 



1 Veiel, v. Ziemssen's " Handb. d. spez. Path. u. Therap.," 1884, xiv. 



2 Kaposi, " Path. u. Therap. d. Hautkrankh.," 1899. 



3 Saalfeld, Lesser's " Encyclop. d. Haut- u. Geschlechtskrankh.," 1900. 



4 Jessner, " Kompend. d. Hautkrankh.," 1906, 3rd ed. 



5 , 6 Weyl and Geber, v. Ziemssen's " Handb. d. spez. Path. u. Therap.," 1884, xiv. 

 7 de Amicis, quoted by Lewandowsky. 8 Majochi, Centralbl. f. Bakt., xxv. 



9 Dubreuilh, La Prat. Derm., Paris, 1901. 

 10 Mibelli, quoted by Lewandowsky. M Ivers, ibid. 



12 Hiinsche, Munch, med. Wochemchr., 1900, xiv. 



13 Mulder, Weekbl. v. het Nederl. Itjdschr. v. Geneesk., 1889. 



14 Lewandowsky, Deutsch. med. Wochenschr., 1907, xx. 



