3 82 



THE ANIMAL PARASITES OF MAN 



in length) of the parasite ; the males are rarely met with as they 

 die off after copulation, the females die after depositing their 

 eggs. The six-legged larvae hatch out after four to eight days, 

 and after about a fortnight, during which time they change their 

 skins three times and undergo metamorphosis, they begin to 

 burrow themselves. Transmission from person to person rarely is 

 effected through linen, but by direct contact (as in coitus) ; trans- 

 mission can be artificially effected on horses, dogs, and monkeys, 

 but not on cats. 



The smaller Sarcoptes scabiei crustosce, Fiirstenberg, is the cause 



of the scabby itch that occurs 

 chiefly in Norway ; it is not 

 yet certain whether this is a 

 distinct species of itch-mite. 

 The following forms may be 

 transmitted from DOMESTIC 



ANIMALS to MAN : 



(1) Sarcoptes scabiei, var. equi. 

 Male, 0*2 0*23 mm. long ; 0*16 

 0*17 mm. broad. Female, 0-40 

 0*42 mm. long, 0*28 0^32 mm. 

 broad. The horse is the normal 

 host. 



(2) Sarcoptes scabiei, var. ovis. 

 Male, 0*22 mm. long; 0*16 mm. 

 broad. Females, 0-32 0-44 mm. 

 long -0*24 0*36 mm. broad. This 

 mite lives on sheep, and passes 

 over to goats and human beings ; 

 it may also be artificially trans- 

 ferred to horses, oxen, and dogs. 



(3) Sarcoptes scabiei, var. caprce. 



FIG. 2 4 4.-Sarcoptes scabiei, male, ventral. Male > ' 2 4 mm. long, 0*188 mm. 

 aspect. 200 i; (After Fiirstenberg.) broad. Female, 0*345 mm. long, 



0x342 mm. broad. On goats, 



passing from them to horse, ox, sheep, pig and man. In the latter, in con- 

 tradistinction to the varieties i and 2, it produces a severe affection. 



(4) Sarcoptes scabiei, var. cameli. Frequently observed in man, chiefly in 

 Africa. A few cases have been observed in Europe ; the affection induced 

 by it is severe. 



(5) Sarcoptes scabiei, var. auchenice. Male, 0*245 mm. long, 0*182 mm. 

 broad. Female, 0*34 mm. long, 0*264 mm. broad. It lives on the Llama, 

 and may be transmitted to man. 



(6) Sarcoptes . scabiei, var. suis. Male, 0*25 0*35 mm. long, 0*19 0*3 



[This mite produces the so-called " Black muzzle " of sheep. F. V. T. 



