140 ANNUAL REPORT OF THE Off. Doc. 



{strongylus 7mcruS'Wi) has always been known in certain parts of 

 the State, but this past year it has caused more damage than usual. 

 It may be that the damp, cold season has some relation to this 

 unusual prevalence. At any rate, it has been observed that during 

 dry seasons lung worm disease of calves is less prevalent. The 

 parts of Pennsylvania that are most seriously afflicted with this dis- 

 ease are the northern counties, those adjacent to New York state, 

 and in a few of the valleys in the central part of the State. Ke- 

 cently, lung worm disease has appeared among cattle in the Schuyl- 

 kill Valley. 



In some parts of the districts mentioned above verminous bron- 

 chitis has proven to be a scourge and through its return from year 

 to year, it has seriously injured and discouraged breeders. The 

 cause of this disease is a thin, round, white worm. These worms 

 reach maturity in the air tubes of young cattle. They are ex- 

 pelled by coughing and afterwards they may continue to live for 

 some time in stagnant water or in damp places. It is not known 

 whether it is necessary for this parasite to pass a part of its exist- 

 ence in an intermediate host, but there is some reason to believe 

 that it is necessary that young parasites developing from the eggs 

 coming from the mature worms that have been coughed out, 

 must pass into some invertebrate animal in order to obtain develop- 

 ment. Cattle are usually infected with this disease in the spring 

 or early summer through taking up the parasites with water or 

 with vegetation growing in damp places. It has also been sug- 

 gested that it is possible that the larvae may be inhaled with dust 

 and dry matter upon the forage. The parasite requires for its 

 development from six to eight weeks. During this time it has 

 migrated to the lungs. Sometimes, the infestation of the lungs 

 is so great as to lead to the almost complete stoppage of the 

 larger bronchial tubes and some of their branches, for distances f 

 several inches. Usually, evidence of disease in the infested calves 

 does not occur until late summer or autumn. On some farms where 

 there is much marshy ground the disease occurs regularly each 

 year about the same time. The effect of the presence of the worms 

 is to cause a severe irritation in the membrane lining of the bron- 

 chial tubes, constituting bronchitis. In fatal cases the inflamma- 

 tion extends beyond the air tubes to the lung tissue proper and 

 jjroduces solidiflcation of the lung. The symptoms usually begin 

 with a severe cough that is repeated frequently and which, in 

 time, becomes very distressing. The animal usually continues to 

 eat well and does not decline in general condition until the cough 

 has become harassing and serious changes have occurred in the 

 lungs; then the appetite diminishes and loss of condition is rapid. 

 Generally, the course of the disease is slow, covering a period of 



