PARASITIC DISEASES OF CATTLE IN PUERTO RICO 21 
cooked beef containing the bladderworms may result in infestation 
with the tapeworm. A man infested with a tapeworm expels several 
hundred proglottids a month, each containing many thousands of 
eggs. Cattle are infested by eating human excrement or by swallow- 
ing the eggs in contaminated feed and water. All beef should be 
thoroughly cooked before it is eaten in order to destroy this inter- 
mediate stage or else subjected to adequate meat inspection by com- 
petent veterinarians. 
The threadworm (Setaria labiato-papillosa) is a slender, whitish 
worm from 2 to 5 inches in length. It usually occurs in the peri- 
toneal cavity. A few of these worms are often found in cattle. 
These worms do not appear to do much damage and are not known 
to cause any definite symptoms. 
The neck threadworm (Onchocerca gutturosa) is found in the 
large ligament of the neck. This is a slender, whitish worm from 
1 to 2 inches or more in length. Most of the cattle that are slaugh- 
tered for meat purposes are infested with this worm. As far as can 
be determined, this worm is not harmful to the animal aside from 
causing a slight local irritation. 
EXTERNAL PARASITES 
CATTLE TICK OR GARRAPATA 
The North American cattle tick (Boophilus annulatus) (fig. 2, D) 
and the Australian cattle tick (B. annulatus australis) are found 
attached to the skin of cattle and occasionally goats and horses. 
These are the common ticks found on cattle. At Mayaguez, the 
Australian variety is more common than the other. 
Life history. — Both ticks mature on cattle and horses and the 
Australian tick matures on goats as well. The engorged female 
drops from the animal to the ground where it may deposit from a 
few hundred to more than 3,000 eggs. The eggs hatch in 2 weeks 
or longer, depending on external conditions. The young seed ticks 
are capable of living 3 or 4 months on the ground, if they do not 
become attached to a suitable host. After attachment the tick may 
become mature within 1 month. The entire life cycle may be 
completed within 6 weeks. 
Importance. — These ticks are very abundant and are one of the 
most serious parasites of cattle. In addition to causing direct in- 
juries, they transmit the diseases piroplasmosis and anaplasmosis. 
Symptoms and lesions. — The direct injury by the cattle ticks is 
chiefly the drawing of blood from the host. As a result, growth is 
retarded, work animals are weakened, and milk production is 
reduced. 
Treatment. — The ticks are controlled by " tickicides " used as 
sprays or dips. At present concentrated proprietary arsenical solu- 
tions are used almost exclusively. As these preparations and infor- 
mation concerning their use are readily available to stockmen, details 
in regard to treatment are not given. 
Precautions should be used in the handling and dilution with 
water of the dips. Often animals are poisoned from too high a 
concentration of the arsenic in the solution. An animal mav ab- 
