566 THE ANIMAL PARASITES OF MAN 



occasionally becomes parasitic in man, and produces very intense itching, 

 erythema and eczema. The acarus which is found in swallows, dermanyssus 

 hirudinis, Hermann, 1804, also occasionally becomes parasitic in man. 



Of the ticks the Ixodes ricinus Linne, 1758, is parasitic in man. The para- 

 site lives upon low bushes and generally attacks sheep, cattle, dogs, cats, and, 

 not rarely, also man. The female bores with its proboscis deeply into the 

 skin to suck blood. It is necessary to exercise caution in removing the insect, 

 as the proboscis tears readily, and if left in the wound causes inflammation. 

 The application of benzine, petroleum, or oil of turpentine readily removes the 

 parasite. 



Not quite so harmless is the bite of the argas reflexus, Fabricius, 1794. 

 It lives in woodwork or masonry, and in some regions attacks pigeons. It 

 occasionally becomes parasitic in man. The parasite produces local inflamma- 

 tion and also certain general symptoms, among which are nausea, pyrosis, diar- 

 rhea, irregular heart action and dyspnea. The poison is said to be contained 

 in the powerfully developed salivary glands. The bite of the argas persicus, 

 Fischer de Waldheim, 1824, and of the argas tholozani, Laboulbene et Meg- 

 nin, 1882, which live in Persia, is said to be dangerous. In the tropics still 

 other members of the family of argas are known (such as the argas turicata 

 Duges, argas chincha, Gervais, etc.), which occasionally attack man and pro- 

 duce disagreeable symptoms. Of the family of the tyroglyphides only the 

 tyroglyphus farinse, de Geer, and the tyroglyphus siro, Linne, the tyroglyphus 

 longior, Gervais, are to be mentioned as occasionally parasitic in man. More 

 important, on account of the extent of its distribution, is the family of sar- 

 coptes : 



Bar copies scabiei, Linne, 1748. 



The knowledge of scabies dates back to antiquity. Aristotle was appar- 

 ently acquainted with the organism. But although the insect was familiarly 

 known for centuries, its natural history having been correctly described and 

 depicted, its parasitic character was not recognized, and the itch was looked 

 upon as a disease produced by an acrimonia sanguinis. This opinion became 

 the prevalent one. It was not until 1834, when the completely forgotten art 

 of catching the acarus was revived, that the pathology of the itch was recon- 

 structed, and .the acarus generally recognized as the cause of the affection. It 

 is hardly necessary to give here a description of the acarus. A microscopic 

 preparation of the acarus may readily be obtained ; in a patient with the itch 

 we look for a large pit which may frequently be seen with the naked eye. 

 This pit is seen upon the hands as a blackish line, and upon the trunk as a 

 whitish punctated line. At the end of this groove, where a whitish discolored 

 point may. be recognized, the epidermis should be carefully removed with a 

 cataract needle, and the insect, which has been laid bare, can be extracted and 

 put upon a slide. 



We can easily recognize upon the head the scissors-Uke jaw feelers with 

 which the impregnated female cuts or bores its way into the epidermis. Grad- 

 ually It penetrates the deeper layers of the rete Malpighii. The bite is fol- 

 lowed by the deposit of an exudate between the cutis and the newest epidermis 



