Pathogenicity of Coccidia in Japanese Quail (Coturnix coturnix japonica)

Abstract

Coccidia were recovered from a field outbreak in commercially raised Japanese quail from South Carolina. After propagation in unmedicated quail, the culture was identified as a mixture of ∼65% Eimeria uzura, 33% E. tsunodai, and 2% E. taldykurganica. Several pure cultures of E. uzura were obtained by single oocyst isolation. A micropyle was not present in all oocysts; thus, it is not a reliable taxonomic characteristic for identification of E. uzura. Neither the mixed culture nor the E. uzura isolates were infective for Bobwhite quail, Chukar partridge, pheasants, chickens, or turkeys. Seventeen-day-old quail were inoculated with various doses of sporulated oocysts ranging from 5 × 102 to 5 × 105 of the mixed culture and 1 × 103 to 1 × 106 of E. uzura. The rate of weight gain was depressed at 3 or 4 days postinoculation (DPI) with as few as 5 × 102 oocysts/quail of the mixed culture. As few as 1 × 103 oocysts of E. uzura produced a weight loss. Some individual quail had depressed packed cell volume and plasma pigment compared with levels in the uninoculated controls. Plasma protein was not affected. Young quail (3 days old at inoculation) were more susceptible than 17-day-old quail. Infection did not adversely affect body weights of adult quail, although egg production was reduced. Mortality was seen only with the mixed culture (100 and 8% in 3- and 17-day-old quail given 5 × 105 oocysts, respectively). Gross lesions of the intestinal mucosa were generally absent, although slight ballooning and bleaching were sometimes seen. Oocyst production 4 to 7 DPI with the mixed culture was greatest at a dose of 5 × 103 oocysts/quail. With E. uzura, total oocyst production was relatively constant over a range of 1 × 103 to 1 × 106 oocysts/quail.