428 PARASITISM AND DISEASE IN RUFFED GROUSE 



Life Cycle and Dissemination. The life cycle of the closely related cecal worm of chickens 

 has been worked out and is essentially the same as that of the intestinal roundworm, the 

 ascarid. Eggs of the worm pass out in the feces and develop to the infective stage in about 

 seven to twelve days. Upon ingestion, the worm larvae are liberated and quickly find their way 

 to the ceca where development to sexual maturity is completed in 56 days. Undoubtedly the 

 cecal worm of grouse undergoes a very similar development. 



Pathogenicity. No evidence of injury to rutled grouse by cecal worms has been uncovered. 

 Usually the number found are very few. 



It is interesting to note that in chickens and turkeys, the cecal worm egg is capable of trans- 

 mitting blackhead. No case of this disease in wild ruffed grouse has been encountered by the 

 Investigation, though it is occasionally found in grouse reared in captivity*. 



Incidence and Importance. The Ughtness of tlie infection and the lack of demonstrable 

 damage done by H. bonasae make it a comparatively unimportant parasite of grouse. Only 1.8 

 per cent of grouse over three months of age were found to be infected. Of the chicks, only 0.1 

 per cent were infected. 



Coccidia (Eimeria species) 



Distribution. One species, Eimeria angusta was described from the ceca of ruffed grouse 

 in Labrador and Alaska'". It has also been found in the spruce grouse. Another species, Eim- 

 eria bonasae was found in the cecum, rarely in the small intestine, of the ruffed grouse in 

 Massachusetts, Labrador, Quebec and Alaska'". This form was also encountered in ptarmigan 

 and later in sharp-tailed grouse. A third species, Eimeria dispersa, has been reported from 

 the bobwhite quail, ruffed grouse, domestic fowl, turkey, pheasant and sharptail. The species 

 encountered in New York are probably the Eimeria bonasae and Eimeria dispersa. 



Description. Coccidia are microscopic protozoan parasites which, in birds, infect the lin- 

 ing cells of the intestine. The mature forms of this parasite, the oocysts, are spherical or oval 

 cysts with distinct cell walls. Coccidia are distinguished from each other by the size and 

 shape of the oocysts and the number of included sporozoites. Eimeria angusta is an elongate 

 form measuring from 16.5 to 17.5 microns^ in width and 27 to 33 microns in length. E. 

 bonasae, almost spherical in shape, measures 21 microns in diameter and is found in the caeca 

 and rarely in the small intestine. The oocysts of E. dispersa are about 19.8 x 17.7 microns. 



Life Cycle and Dissemination. Detailed accounts of the life cycle of coccidia are available 

 elsewhere". Very briefly, the hfe cycle may be outlined as follows. The microscopic oocyst, 

 when discharged with the feces, undergoes internal growth. There develops, within a period 

 of from 24 to 72 hours, four spores, each of which in turn divides into two elongate sporozo- 

 ites. When the oocysts containing the sporozoites are eaten by a bird, the cyst wall is dissolved 

 by digestive enzymes and the sproozoites are liberated. They inunediately proceed to penetrate 

 tile lining cells of the intestine. Ntiw begins a sequence of events characterized chiefly by the 

 growth of the parasites and their tremendous multiplication at the expense of the intestinal Un- 

 ing cells of the host. The cycle of growth terminates in the (le\olii]nneiit of another crop of 

 oocysts. 



Most of the work on avian coccidiosis has been carried out with domestic chickens. In gen- 

 eral the following factors with regard to the spread of coccidiosis would apply to all species 

 of birds: 



* Se« ditruMJon of Diipair in Hanil-rt-arrd Griiuflr, p. 438. 



A A microo it • uoil of microicopic meaiuremenl which «quaU about 1/25,000 of an inch. 



