70 Lungworin Disease. 



filaria is found preferably in bronchi of medium and small size ; 

 Str. commutatns is found in the smaller bronchi and penetrates into 

 the pulmonary tissue after having deposited its eggs ; the same is true 

 of Str. capiliaris, which is found in the small bronchi and alveoli. 

 Str. micrurus is found preferably in the medium-sized bronchi (Jost). 

 The usual habitat of Str. paradoxus is in the medium and smaller 

 bronchi ; but occasionally it is found in the large bronchi and even 

 in the trachea. Otlicr lungworms inlial)it the medium and small bronchi. 

 Trichosoma aerophilum is a parasite of the trachea and of the large 

 bronchi, while the sexually mature individuals of Str. vasorum are 

 found in the right side of the heart and the pulmonary artery ; those 

 ofOllulanus tricuspis in the gastric mucosa. 



The j)ower of resistaiu-e of the woriiis appeais to l)e very poor directly after 

 the embryos are set free out of the egg shell; especially embryos of Str. filaria 

 and of Str. micrurus perish within a short time under unfavorable conditions 

 (putrefactive i^rocesrses, desiccation), while otiierwise they remain alive for weeks 

 and go through one moulting in pure water. After the first moulting, the brood, 

 probai)ly now in a rhalxlitis-iike intermediary form, attains great resisting power, 

 so that it may live in water for months (Eailliet, Baillet, Colin), and may revive 

 after a long period of desiccation. Larvee of Str. filaria were found alive after 

 sixty-three hours of desiccation (Railliet), after a year (Ercolani, Plana), and 

 those of Str. commutatus after fourteen months. Sexually mature worms and their 

 larva; are not very resistant if brought in contact with antiparasitic substances. 

 Plana 's investigations have shown that the larva; are killed at once by an iodine- 

 io<lide of i)otash solution (1:10:100) and by a i'/( cori-osive sublimate solution; 

 by vapors of iodine in one minute; by 15% solution of common salt iu ten minutes; 

 by a 10'// solution of potassium iodide in fifteen minutes. Oil of turpentine, 

 creosote and calomel apparently do not influence the larvie, which, however, do not 

 revive after desiccation followed by soaking in water. Absolute alcohol immolnlixed 

 them for awhile, but they became motile again after some time. 



The natural infection usually takes i)lace with feed and 

 water in pastures Avhich have been contaminated by sick animals 

 and which are sufficiently moist to favor the development 

 of brood. The biologic properties of lungworms bring it about 

 that pastures, once contaminated, remain dangerous for a long- 

 time, because tlie subsequently affected animals keep on furnish- 

 ing the infectious material. Hence the disease becomes sta- 

 tionary in many parts. Other parts which are free from epi- 

 zootics of domestic animals may become infected by wild ani- 

 mals. 



Primarily dangerous are low, marshy pastures and those 

 exposed to repeated inundations, while pastures which are situ- 

 ated favorably are dangerous only during permanent wet 

 weather, even after contamination has occurred. The disease oc- 

 curs under the latter conditions only in occasional outbreaks and 

 at prolonged intervals which may extend to several years. Long 

 lasting rainy weather naturally increases the danger, even in 

 lowlands, and during very wet years the disease sometimes 

 assumes an epizootic character over a larger territory. The 

 disease is observed exceptionally in dry years. Under such 

 circumstances the infection may occur by the inhalation of 

 worm larva? which may get into the air M^ith dried and pulver- 

 ized swamp material, or with material which by rain and winrl 

 may have been deposited previously on feed plants. 



