PARASITES AND PARASITIC DISEASES OF SWINE 
ll 
pork products is necessary to prevent infestations with the tape- 
worm in man. 
OTHER INTERNAL PARASITES 
Several other worm parasites occ ur in the pig. As far as is known 
they are of relatively Less importance in Puerto Rico than those 
already described in this bulletin. Usually the common worms of 
the pi<j: can be identified from their gross appearance and precise loca- 
tion in the intestinal tract or elsewhere in the body. The morpho- 
logical differences between two closely allied species, Mich as the 
lungwormsor nodular worms, are unimportant from a practical view- 
point. Any unusual parasites that are encountered in livestock should 
be Bent to the experiment station at Mayaguez for identification. 
The red stomach worm, Hyo&trongylus rubidus (fig. '2. Z/), is a 
small, hairlike, reddish worm. Close examination is necessary to 
discern these worms in mucus scraped from the lining of the stomach. 
Heavy infestations may produce a catarrhal condition. The mainte- 
nance' of clean, dry quarters for swine is the indicated control measure. 
The strongyline stomach worm, Ascarops strongylina (fig. 2, G), 
is a small white worm somewhat larger than the red stomach worm. 
It varies from 1 to 2.2 cm (approximately M> *° 1 inch) in length. 
These worms may be embedded in the lining membrane of the stomach 
or are sometimes unattached and entangled in a mass in the lumen 
of the stomach. Because of the habit of burrowing, they may cause 
considerable injury to the stomach. As dung-frequenting beetles are 
intermediate h<»ts of this worm, prevention depends on the frequent 
and thorough cleaning out of manure in order to prevent the beetles 
from feeding on it. The giant toad might be useful in controlling 
these beetles. About 50 percent of pigs slaughtered at Mayaguez 
are infested with one or the other or both species of stomach worms. 
The roundworm or ascarid, Ascan's lumhricoides (fig. 2, is 
a thick yellow or pink worm varying from 6 up to 10 or more inches 
in length. It is unattached and is usually found in the lumen of the 
small intestine. If numerous, these worms are very serious, causing 
digestive disturbances, malnutrition, and stunting in young pigs. 
In Puerto Rico infestations are uncommon and usually consist of only 
a few worms. 
The American swine hookworm, Necatw striHus (fig. 2, D). located 
in the. small intestine, is somewhat longer and more robust than the 
common hookworm (p. 8). A few pigs lightly infested with this 
worm have been found at Mayaguez but further information as to 
the economic importance of this worm is lacking. This worm is 
common in Trinidad. 
The nodular worms, Oesophagostomv. m dentatvm and 0-. longi- 
caudum (fig. 2, /). are roundworms found as adults in the large 
intestine. They vary from 8 to 14 mm (approximately % to y 2 inch) 
in length. Some of these worms are white but the majorit}^ are of 
a grayish-brown color. Heavy infestations of this worm are com- 
mon in the wet coastal areas. These worms are not as serious in 
pigs as the nodular worms in calves. Control measures depend on 
-.•miration, proper manure disposal, and general cleanliness about 
yards or buildings occupied by swine. 
