Etiology. Pathogenesis. 477 



and they sonietiines xjermaiiently infect the floor of certain barns ; 

 from these phxces they may be taken np by healthy animals 

 or by animals already infected, or they may further spread 

 and contaminate feed, water or other objects in the neig-hbor- 

 hood of the animals. Railliet saw an epizootic of ascaris infec- 

 tion in 250 horses, due to the ingestion of infected turf straw. 

 Gasteiger found ova of ascaris in large numbers in the manure 

 and outside of the barn in leaf bedding, where they had been 

 transported by the shoes of attendants and small animals (the 

 infection of the leaves miglit have occurred in the woods 

 by free living wild animals). Sucking animals usually infect 

 themselves, swallowing ova which have been transported from 

 the bedding straw to the udder or by licking, in a playful man- 

 ner, straw or manure infected with ova. This may explain the 

 enzootic occurrence of ascaris infection among the calves of 

 Miesbach-Tegernsee, where calves have a strong desire to lick 

 soon after birth (Gasteiger). This mode of infection explains 

 how young animals, wliicli aside from mothers' milk receive no 

 food or water, may become infected with ascaris (Grassi, Froh- 

 ner, Penperthy, Albrecht, Leibenger, Gasteiger). If newborn 

 calves suffer from diarrhea (dysentery), the ingested ova are 

 expelled and cannot become parasitic in the intestinal tract 

 (Gasteiger). 



Jammes & Martin call attention to the fact that the susceptibility of the 

 individual animals depend upon the chemical composition of the gastric juice, and 

 this again varies according to the condition of the digestive organs, the species, 

 age and general health of the animals. According to the authors named, acid 

 gastric juice, as found in the stomach and possibly in the first portion of the 

 small intestines, favors segmentation, while the alkaline intestinal juice favors 

 the escape of the embryo out of the egg shell. 



Pathogenesis. Aside from mechanical injury (irritation of 

 the intestinal mucosa, stenosis of the intestinal lumen, possibly 

 rupture) one must, according to Gasteiger, consider the effect 

 of poisonous metabolic products formed by certain enzymes of 

 Ascaridae. These products preferably cause nervous disturb- 

 ances and inflammatory changes. Mingazzini succeeded in pro- 

 ducing convulsions with extracts of Ascaridae, also paralysis, 

 sometimes even fatal affections. Inflammation of the conjunc- 

 tiva, due to contact of the latter with ascaris, has repeatedly 

 been seen in man (Kitt, Gasteiger). Aside from metabolic prod- 

 ucts, other matters due to decomposition of the dead worms 

 may, according to Gasteiger, play a certain role; this is, per- 

 haps, indicated by the observation that the administration of 

 vermifuges is followed by a short period of increase of the symp- 

 toms of ascaris infection. It is also claimed that ascaris ex- 

 crete fatty acids which impart a peculiar smell to the organs 

 of the host. Nutritive disturbances which occur in the course of 

 ascaris infection are probably mostly due to the abstraction of 

 nutritive material, and to the fact that the mature w^orms suck 

 blood from the intestinal wall (Schimmelpfennig). 



