CYSTICERCUS OVIS, THE CAUSE OF TAPEWORM CYSTS 
IN MUTTON 
By B. H. Ransom, 
Chief , Zoological Division, Bureau of Animal Industry 
INTRODUCTION 
It has been known for nearly half a century that cysticerci occur in 
mutton, but they have generally been looked upon as zoological curi¬ 
osities rather than parasites of real economic importance; in fact, it 
seems that this opinion has been so commonly accepted as an established 
truth that a systematic examination of sheep for such cysticerci, or 
measles, like that given cattle and hogs, has been considered unnecessary 
by meat-inspection authorities. So far as this country is concerned, 
however, the belief that sheep measles are rare has been lately discovered 
to be quite erroneous. Instead of being rare, sheep measles have been 
found to be of much the same order of frequency as beef measles and far 
more common than pork measles, which are almost unknown in the 
United States. Where the presence of measles has been carefully looked 
for, the percentage of affected sheep has run 2 per cent and over, and 
during the calendar year 1912 approximately 20,000 sheep carcasses were 
retained under Federal inspection at various abattoirs on account of 
measles, most of them during the last few months of the year. 
In the light of these figures it is quite evident that the mutton cysti- 
cercus is far from being the unimportant parasite it is commonly assumed 
to be, and it is furthermore quite certain that as inspectors become gen¬ 
erally more familiar with this parasite and with the proper methods of 
inspecting for its presence the percentage and gross number of cases 
found will materially increase. 
As yet sufficient data are not at hand to indicate the extent of direct 
injury to sheep by the measles parasite, so that the chief practical impor¬ 
tance of sheep measles recognized at the present time is in their relation to 
meat inspection and public health. Like beef and pork cysticerci, the 
mutton cysticercus is of special interest in meat inspection because it 
affects the musculature, that part of the animal which is at once the most 
valuable for food purposes and the most difficult to inspect thoroughly. 
The beef and pork cysticerci are well known to be the intermediate 
stages of two species of tapeworms occurring in man. The question 
naturally arises, Is the mutton cysticercus likewise the intermediate stage 
of a human tapeworm ? The leading foreign meat-inspection authorities 
have held that the mutton cysticercus is simply Cysticercus cellulosae , 
the pork cysticercus, in an unusual host, and have laid down identical 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
( r s) 
7954 °—13-2 
Vol. I, No. 1 
Oct. 10,1913 
A—1. 
