stomach-worm Disease of Sheep and Goats. 457 



(b) Stomach- worm Disease of Sheep and Goats. Strongylosis ven- 

 triculi ovum et caprarum. 



Occurrence. The disease occurs in marshy territories, ex- 

 posed to frequent rains and inundations, and it sometimes 

 causes great losses. Animals of all ages are affected, but pref- 

 erably only lambs, kids and yearlings. The affection is fre- 

 quently seen simultaneously with the lung-worm-, or the liver- 

 fluke disease. 



Etiology. The disease is caused by strongylidae, most com- 

 monly by Strongylus contortus, more rarely by Strongylus fili- 

 collis, Strongylus vicarius, Strongylus circumcinctus, Strongy- 

 lus retortseformis, Strongylus Ostertagi or by other species of 

 strongylus. 



strongylus contortus is a filiform worm one to two cm. long (females two to 

 three cm.) ; its red color is believed by the majority of authors to be due to blood 

 coloring matter obtained from the stomach; others, however, including Lignieres, 

 think that the coloring matter is not hemoglobin. 



The embryology of the stomach strongylidce has not been definitely 

 settled; the investigations of Ransom, Plana and Stodter have shown, 

 however, that the ova of Strongylus contortus, Strongylus Ostertagi and 

 Strongylus retortfeformis, voided with the feces of infected animals, un- 

 der favorable conditions of temperature, discharge embryos which obtain 

 their nutrition from the excreta in which they were set free and grow 

 up to the size of about one mm. If the larva are then taken up by 

 sheep they attain their full length after a sojourn of two to three weeks 

 in the abomasum of these animals. 



The resistance of the larvae is very great. According to Eansom they can 

 stand desiccation for thirty-five days, and according to Piana up to ten months. 

 They become immobile in much water; can, however, revive later on. They can 

 stand the cold of winter without any harm and remain alive on pastures for seven 

 or eight months. 



Natural infection occurs during pasturing by the ingestion 

 of plants contaminated with Strongylus larvae, possibly also with 

 the drinking water. Lambs are said sometimes to become in- 

 fected during barn feeding (Michalik). Eggs as well as em- 

 bryos up to their fourth to fourteenth day of embryonic life are 

 not infective (Ransom). 



Pathogenesis. The strongylidae bore into the gastric mu- 

 cosa and suck blood from it ; in this manner they disturb the nu- 

 trition of the hosts in a degree proportionate to their number. 

 More detrimental than the loss of blood is, however, probably 

 the absorption of toxic metabolic products (according to Grrosso 

 hemolysins) of the parasites. 



The injuries produced by the parasites afford an opportunity for bacterial in- 

 vasion. Lignieres showed that a disease prevalent in Argentine and known under the 



