Enumeration and speciation of coccidia affecting turkeys using flow cytometry method

Abstract

Enumeration of Eimeria oocysts is a common practice in monitoring coccidiosis in turkeys; however, the conventional method of manual microscopic examination of Eimeria oocysts is time-consuming. Previously, we used flow cytometry ( FCM ) to enumerate and speciate coccidia affecting chickens and here, we extended those findings to turkey coccidia species, E. adenoides and E. meleagrimitis . Using FCM, a commercial vaccine containing these species was used to optimize the scatter-plot parameters, including Forward-(size) and Side-(shape/granularity) scatter Area, Height, and Width patterns for Eimeria . The two Eimeria species populations in the vaccine were accurately phenotyped and the gated populations were then sorted using a Cell sorter instrument to obtain pure oocyst suspensions. The individual Eimeria species identity of sorted oocysts was confirmed by PCR using species-specific primers. A significant ( P = 0.0466) correlation (R = 0.9893) in the total oocyst count between FCM and manual methods were observed. Furthermore, when FCM was employed to analyze farm fecal samples, the close similarities in the oocyst morphologies coupled with organic debris particulate interference prevented a precise separation of these 2 species resulting in a lack of oocyst count ( OPG ) correlation between the 2 methods. The OPG counts by FCM were much lower than the manual method; however, a partial OPG trend between the two methods was observed only at the early timepoint collections during a period of 35 d. Collectively, our findings showed that FCM can be used in the enumeration of turkey Eimeria oocysts with a potential scope for a more precise enumeration and speciation in field samples.