14 BULLETIN 260, U. S. DEPARTMENT OF AGRICULTURE. 



so that neglect on the part of sheep owners is a leading reason for 

 its prevalence. 



The prophylactic measures against " sheep measles " are essen- 

 tially the same as those against gid and hydatid. Diseased portions 

 of slaughtered sheep and dead sheep which have not been slaughtered 

 should be cooked before being fed to dogs or else disposed of so that 

 dogs can not eat them. Ownerless dogs should be destroyed and other 

 dogs properly fed and kept free from tapeworm. 



Muscular cysticercosis (" measles ") in reindeer. — This parasite 

 deserves special mention in view of the possibility that the Alaskan 

 reindeer may become important in connection with the meat supply 

 of this country. A large percentage of these animals, which are 

 rapidly increasing in numbers, are infested with a measle parasite 

 apparently the same as the form known to be the 

 intermediate stage of a dog tapeworm {Tcenia 

 krabbei). This is not only serious so far as con- 

 cerns the reindeer industry, but the possibility that 

 the parasite may become established in other food 

 animals is not altogether excluded, though prob- 

 ably remote. Tcenia hrabbei occurs in Europe and 

 Asia and was likely introduced with the reindeer 

 or dogs imported into Alaska, though the Alaskan 

 form may be a native parasite already present in fig. 8.—cysticercus 



. . . n -, . i p ii • tenuicollis, the 



American reindeer and carnivores before the lm- thin -necked biaa- 



portation of the Old World animals. tfer worm from 



Cysticercosis of livers and mesenteries. — Cysti- cattle 7 ^h'eep 



cercosis, or the presence of cysticerci, or bladder swine, etc Natu- 



ji v , -i , ral size (after 



worms, m the livers, mesenteries, and omentum' or gtiies) 

 " fat caul," is very common in cattle, sheep, and hogs 

 throughout the United States. These bladder worms, Cysticercus 

 tenuicollis (fig. 8), are usually 1 or 2 inches in diameter, and the 

 cyst contains a single tapeworm head. The life history follows 

 the same general plan that has been outlined for the preceding tape- 

 worms. When such bladder worms, or viscera containing them, are 

 eaten by dogs, the head contained in each cyst passes to the intestine 

 and develops a tapeworm {Tcenia hydatigena or Tcenia marginata) 

 (fig. 9) in the dog; the eggs produced by the tapeworm pass in the 

 feces of the dog onto the vegetation or into the drinking water of 

 cattle, sheep, and hogs ; the eggs ingested by these animals in feeding 

 or drinking release an embryo which makes its way, via the portal 

 system, from the digestive tract to the liver ; in the liver the embryo 

 develops into a small bladder worm (Cysticercus tenuicollis) which 

 after some time slips from the liver into the body cavity and lodges 

 in the omentum or mesenteries, where it attains its final growth ; the 

 bladder worm may then be eaten by a dog, on the death of the host 



