Is BULLETIN 36, PUERTO RICO EXPERIMENT STATION 
iriant grasses and provided with clean, dry pens. In the dry areas 
and mountain regions, calves should be pastured ou the hillsides 
and should n<»t have access t<> wei <»r marshy land. 
UVEH FLIKK. - UNGUA " OR " ( l( ARACHA " 
The liver fluke {FascMa hepatica) (tin-. :;. // i \s found usually in 
the canals and duct- of the liver, although the flukes may occur as 
wandering parasites in the lungs and elsewhere. This fluke is a 
flattened, leaflike, brown animal about 1 inch long. 
Lifi history. — The eggs pa— out in the feces ;md. if they get to 
water, they develop in about 3 weeks and release a motile embryo. 
This embryo swims about and enters a snail (Lymnaea oube\ 
in which another stage of development take- place. A small fluke- 
like cercaria with a tail is produced in the snail, and this cercaria 
emerges and swims about and in a short time encysts. This en- 
cysted form may float on water or it may become attached to grass. 
When these are swallowed by cattle or other suitable h<>.-t animals. 
the larval flukes escape into the digestive tract and bore their way 
through the intestinal walls to the body cavity. A> a rule, they per- 
forate the capsule of the liver and enter the bile ducts, while a lew 
may perforate the diaphragm, getting into the lungs. 
Importance. — The liver fluke is a common and serious pest of 
cattle in the wet coastal and lower mountain areas. This parasite 
also infests the goat, pig. horse, and man. Mature animal- as well 
as the young may suffer serious injury or die from infestation. In 
daiiy cows there is a loss in milk production and breeding efficiency. 
Work bulls are weakened and made unfit for service. There is 
another loss in that all infested livers are condemned at the 
abattoirs. 
Symptoms end lesions. — Loss of condition, anemia, and edema are 
associated with this parasite. The fluke causes considerable dam- 
age to the liver, which in cattle especially is of a permanent nature. 
since heavy infestation in cattle is followed by a calcification of the 
bile ducts. Complete recovery is hardly possible because of the 
permanent injury to the liver tissue. 
Treatment. — Xo treatment is recommended for flukes in cattle. 
The permanent injury to the liver cannot he relieved or improved 
by treatment. Infections in cattle may be controlled by destruction 
of the snails responsible for carrying the young fluke-. 
Prevention. — The snail which is essential to complete the life cy- 
cle of this fluke can be destroyed by proper drainage or by treating 
the water and mud with copper sulphate. This snail lives in the 
mud. in stagnant fresh water, and in sluggish streams and drai] 
ditches hut not in swift -running water or in gravelly stream beds. 
A mixture of 1 part powdered copper sulphate to 4 or v part- of 
dry -and may he broadcast by hand over the snail-infested areas at 
the rate of :> to 6 pounds of copper sulphate to the acre. 
The snails in streams and ditches may he destroyed by putting 
a gunny sack containing crystals of copper sulphate in the head 
water-. Damming the stream- at intervals aids in destroying snails 
along the hanks. The copper sulphate is capable of destroying the 
-nails in a stream as far down a- the water retain- a bluish color. 
