418 PARASITISM AND DISEASE IN RUFFED GROUSE 



ported ill chickens, bobwhitc quail, turkeys, pheasants, peafowl, red grouse, sparrows, thrushes, 

 crows and a number of other birds as well as in ruffed grouse. It has been considered as asso- 

 ciated with pheasants and domestic birds for so long that it was surprising to find it occurring 

 in areas in the deep Adiroiidacks where poultry has never been raised. It has been found in 

 several widely separated localities in New York but its incidence is so low that its absence in 

 specimens from other regions is no indication that it is non-existent there. 



Description. This worm, sometimes called the "Y" worm, because the male and the female 

 are joined together in the form of a Y, is found attached to the mucous membrane of the 

 windpipe. The worms are blood-red in color. The males measure up to ' i incli long, and 

 the females up to 'J^ inch in length. Cram"" has given a complete description. 



Life Cycle and Dissemination. The eggs are deposited in the windpipe by the female, are 

 coughed up, swallowed and passed out with the feces. Under optimum conditions of tempera- 

 ture and moisture, development to the infective stage takes |)lace in about seven (ia\s. Infec- 

 tion results when a susceptible bird eats either the embryonated eggs or certain invertebrates, 

 such as earthworms and snails, in which the infective larvae are loosely encysted"-*". Within 

 a day after ingestion, the larvae migrate to the lungs. According to W'ehr'" this migration 

 takes place by way of the blood stream. The males and females jjair as young adults in the 

 lung and then move up the bronchi to the trachea where attachment occurs. The worms ma- 

 lure within 1 7 to 20 days after infection. 



The spread and maintenance of this infection in any one species is influenced by the follow- 

 ing considerations: 



1. Gape worm larvae encysted in earthworms mav remain viable and produce infection for 

 longer than four years as demonstrated by Taylor*". 



2. Man> species of small wild birds are found to be infected with the same species of worm. 

 .■^. In some species of gallinaceous birds there is a definite age resistance to infection. Adult 



chickens, for instance, are rarely infected, while very young fowl become infected with 

 comparative ease. I iirkc\s on the other hand retain the infection at all ages. It is in- 

 teresting to note that the incidence of gape worm infection in grouse chicks (0.0 per- 

 cent) is more lluiii four times the incidence in adults. 

 It is possible that the extreincK low incidence of the iiifc( tion in \ew York groii>c i> due to 

 the fact that the ex|)osure to infection may be very light and scattered. Gape worm infection in 

 domestic chickens and turkeys in this State is seldom encountered by the diagnostic laboratory 

 at the New York Slate Veterinary College. 



Serious reservoirs of infection may exist on pheasant farms. Here the gape worm disease has 

 been known to lake a lieavv toll of pheasant chicks unless the young birds are raised on soil on 

 which pheasants have not hccii prc\iip|isl\ reared for a period of at least three \ears. 



Pathonenieity. The abilitv of ga])e worms to produce disease in pheasants and domestic 

 poultry is well known. The blood .-iucking activities of the worm and the nu'chanical block- 

 ing of the windpipe are serious enough to cause the death of heavily infected birds. In native 

 wild grouse, however, the number of parasites encountered has never been more than eight 

 pair and in none of these birds was there evidence of serious injury. The onl\ evidence that 

 S. trachea can be serious for grouse was observed in 1932. A wild trapped female grouse 

 shipped to New York was found to have died as the result of suffocation by 35 worms packed 

 in the lower end of the windpipe. This bird was being used as a breeder and was confined in 

 a large pen on ground where n<i galliiKi<<'ous birds had previously been raised. It could not be 



