10 BULLETIN 939, U. S. DEPARTMENT OF AGRICULTURE. 



SIGNIFICANCE OF TURKEYS IN RELATION TO GAPES FORMERLY 



UNRECOGNIZED. 



From the literature on gapes one may gather further evidence of 

 the importance of the turkey as a carrier of gapeworms, though the 

 peculiar significance of the turkey in relation to gapes has not been 

 recognized by former writers. In the first published record of gapes 

 Wiesenthal (1799) called attention to the frequent occurrence of the 

 disease in Maryland and stated that it was most prevalent among 

 young turkeys and chickens bred upon old-established farms. The 

 first published record of gapes in England is that of Montagu 

 (1811), who notes that it generally attacks chickens at the age of a 

 month to 6 weeks, and that it " seems to be peculiar to the young 

 of the common domestic fowl, since neither my turkeys nor ducks, 

 all of which are reared together upon the same spot, have even been 

 attacked." 



Von Pocci (1904), in discussing an outbreak of gapes among 

 young pheasants in Bavaria, which killed about 60 per cent of the 

 birds, incidentally remarks that turkeys were used as brood hens 

 for young pheasants. The first record of gapes in Norway (Home, 

 1910) is based upon the discovery of gapeworms in two young 

 turkey poults and two young chickens from the same poultry farm. 

 How frequently turkeys have been associated with the occurrence 

 of gapeworms among chickens, pheasants, and other birds in Europe 

 is not indicated in the published reports that have come to the 

 writer's attention other than those just mentioned. These, however, 

 are very suggestive and, together with the observations recorded in 

 the present paper, may be taken as an indication of the probability 

 that the turkey has been chiefly, if not entirely, responsible for the 

 spread of the gapeworm to various parts of the world. 



TURKEY THE PREFERRED HOST OF THE GAPEWORM. 



It would seem quite probable that the gapeworm, like the turkey, 

 was originally limited to America and that it has reached other 

 countries only as it has been carried by the turkey, which, because 

 of the tolerance it has to infestation with the gapeworm, may be 

 looked upon as the natural host of this parasite. 



The fact that the gapeworm in turkeys grows to a larger size than 

 it does in chickens may be taken as evidence, in addition to that 

 already given, that the turkey as compared with the chicken is the 

 preferred host of the parasite. The difference in the size of the 

 worms may be a simple correlation with the size of the trachea, but 

 it seems more likely that other conditions than the mere size of the 

 trachea play a part in bringing about the differences in the size of 

 gapeworms in chickens and turkeys. The maximum length of gape- 



