THE DOG AS A CARRIER OF PARASITES AND DISEASE. 5 
and deaths. In 1911, according to Stimson, 1 there were 94 fatal 
cases in man, a decrease from the figures for 1908, which is probably 
due largely to the fact that in 1911 there were 4,625 persons treated 
for rabies in this country. Mohler 2 states that there are only three 
States in the Union — Idaho, Utah, and Nevada — from which it has 
been impossible to obtain positive information to the effect that cases 
of rabies have been found in them. The disease has since been 
reported from Idaho and Nevada. 
Rabies is an easily preventable disease. In the present state of our 
knowledge as to its mode of transmission, there is no reason for its 
continued existence. It may be prevented and in time eradicated by 
simply muzzling dogs. for a sufficient period to allow the disease to die 
out. Such a minor restraint on the dog as muzzling was sufficient to 
eradicate rabies from England. The first case since 1902 has just been 
reported in the spring of 1915, and this case occurred in a dog that was 
being held in the six months' quarantine which is enforced on ail dogs 
brought into that country to prevent the disease being reintroduced. 
Australia and New Zealand have never had any cases of rabies, and 
a system of quarantine and inspection is provided to prevent its intro- 
duction. It has been practically or completely eradicated from 
Sweden, Norway, and Denmark by rigid enforcement of muzzling 
ordinances. 
HYDATID. 
Hydatid disease occurs in man, cattle, sheep, horses, hogs, and 
numerous other animals. It is caused by the presence of the so- 
called hydatid (technically known as Echinococcus polymorphus, 
Echinococcus granulosus, Echinococcus multilocularis, etc.) in such 
tissues as the liver, kidney, muscles, brain, lungs, etc. The hydatid 
is a bladder worm or larval tapeworm (fig. 2), and is characterized 
by its thick laminated cyst wall. The original bladder frequently 
develops daughter bladders on the inside or on the outside, and in 
these or the original bladder there develop brood capsules containing 
tapeworm heads. There are probably two species of hydatid, though 
they are commonly considered a single species. The bladder worms 
are often as large as an orange and may be as large as a child's head. 
Growth and the formation of daughter bladders may go on for an 
indefinite period. There have been cases in which hydatids have 
existed in man as long as 30 years before the death of the patient 
finally ensued. Their presence in the body causes various forms of 
1 Rabies in the United States during the year 1911. By A. M. Stimson. Public Health 
Reports, vol. 27 (28), July 12, 1912, pp. 1098-1101. 
2 Rabies or hydrophobia. By John R. Mohler. Farmers' Bulletin 449. Washington, 
1911. 
