Re-evaluating the host specificity of thirteen Eimeria species that infect galliform birds: Cross-infection experiments in chukar partridges (Alectoris chukar), Northern bobwhites (Colinus virginianus) and Turkeys (Meleagris gallopavo)

The commercial poultry industry has expanded and profited from intensively rearing birds, but it is not without consequences. Coccidiosis is an intestinal disease caused by Eimeria species that is well recognized by poultry producers because of the resulting health implications that often contribute to reduced welfare of birds, meat production and profitability. Strict host specificity of these parasites (infection of one host species only) is often assumed; however, examples of Eimeria spp. capable of infecting multiple galliform hosts have been described. Despite the relevance of coccidiosis in commercial poultry production, the number and extent of such cross-infections remain poorly understood, potentially limiting the species considered during diagnoses. In the present study, the host specificity of Eimeria spp. isolated from chukar partridges, turkeys and chickens were assessed by cross-infecting the coccidia of each host in chukar partridges, Northern bobwhites or turkeys. While the coccidia from chickens and chukar partridges demonstrated strict host specificity, some Eimeria spp. from turkeys infected multiple hosts: Eimeria dispersa and E. innocua were shed by both chukar partridges and Northern bobwhites; and, oocysts of E. adenoeides were recovered from chukar partridges only. Turkeys infected with E. dispersa or E. innocua shed more oocysts in each case than Northern bobwhites that received the same inoculation dose. Despite being less productive in Northern bobwhites, infections of these Eimeria spp. could potentially contribute to cases of coccidiosis in captive populations of susceptible gamebirds reared at high densities and in close proximity to domestic or wild turkeys.