ITCH MITES. 297 



CASE who are sound by actual contact. In some instances, it may be 

 conveyed to the person in its adult state ; while in others, ova, 

 or embryos suspended in the fluid of the vesicles, may be the 

 mode of transmission. Certain it is, that the application of one 

 of the mites to the skin of a sound person will give rise to the 

 disease. The precise mode of its transmission, however, was for 

 a time a puzzle. Its contagious nature could not be disputed, 

 but it was remarked with surprise that infection among doctors 

 and hospital attendants was comparatively rare. Dr. Aube set 

 himself to find out the cause of this, and he learned from a great 

 number of inquiries at patients as to the manner in which they 

 had contracted the disease, that it was almost always by having 

 slept in the same bed with an infected person. He found that 

 the number of those who had so contracted it was to those who 

 had acquired it by manual contact as 100 to 5. Dr. Aub6 

 inferred from this, that the mite was a nocturnal animal, and his 

 other observations and an experiment made upon himself con- 

 firmed this view. The animal hides under the skin during the day, 

 but walks about at night, perhaps excited by the greater warmth 

 of the body in bed, and pricks the skin in various places. This 

 explains the rarity of contagion during the day and the small 

 number of burrows that may be remarked on the skin even where 

 there are a great number of pustules, and also why the violent 

 itching only occurs during the night. In confirmation of what we 

 have said, we may quote the statement (Amer. Ent. ii. 118) that 

 in the great hospital at Vienna, 1500 cases are treated yearly, and 

 no attempt at diisinfecting the clothing is found necessary. The 

 under clothing should be washed thoroughly, but outside garments, 

 contrary to the general opinion, do not need anything to be done 

 to them. 



The best mode of treatment for getting rid of the parasite is 

 very simple. So long as it was supposed to be some mysterious 

 disease whose cause was unknown, it was not, to be expected that 

 it could be successfully treated, but now that we know all the 



