92 



NEMATHELMINTHES 



Family 3. Strongylidae. — This family is of especial interest to us 

 since it includes the hookworm of man, the gapeworm of fowls, and 

 many other internal parasites infesting domestic animals. While 

 these parasites are ordinarily found in the digestive tract, strongylosis 

 may be bronchial or pulmonic, intestinal, vascular or renal. Young 

 animals suffer more than adults. Larvae of the hookworm cause 

 profound irritation as they bore through the skin of the feet into 



lymph spaces. 



Dictophyme renale {Eustro7Jgylus visceralis) 

 {S. gigas, Rud) is the largest of the Nema- 

 thelminths. The females may reach a length 

 of 39 inches. It infests the kidneys of Carni- 

 vora (dog), Ungulata (horses, cattle) and 

 even man. 



Strongyloidea {Dictyocaulus viviparus) 

 {Strongylus tnicrurus) infests the bronchi and 

 air cells of cattle and causes verminous bron- 

 chitis. Dictyocaulus filaria infests sheep, 

 goats and camels, attacking the bronchi and 

 lungs. Metastrongylus elongatus attacks the 

 bronchi and lungs of hogs. Strongylus elon- 

 gatus paradoxus infests the fourth stomach 

 (abomasum) of sheep, goats and cattle. 

 Strongylus equinus bores through the gut into 

 the blood vessels and causes aneurisms in the 

 mesenteric vessels of the horse. Numerous 

 other forms infest the domestic animals. A 

 (After Jordan and Kel- very common parasite of the fowls is Syn- 

 logg, Animal Life. ^^^^Z^J trachealis (Figure 37), the " gape- 

 Courtesy of D. Appleton >> T L ^ • 1 r 

 ^ r- . worm. In the tropics several cases or 



human mrestation by gapeworms nave been 

 reported this year (1931). 



Oesophagostoma radiatum forms cysts in the mucous membrane of 

 the intestines of cattle. 0. columbianum, the nodular worm of sheep 

 and cattle, produces nodules in the large intestine which have been 

 mistaken for intestinal tuberculosis. 



Necator americanus., the hookworm of man (Figure 50, A., 5, C 

 and D), causes tibial ulcer and dirt eating, besides weakness from 

 loss of blood. The symptoms of hookworm include paleness, thin- 

 ness, dull skin and eyes, dry hair, weakness, a depraved appetite for 



Fig. 37. Syngamus 

 trachealis, the^ape-worm 



