Image analysis for Eimeria oocyst counts and classification

The McMaster counting technique is the standard method used to enumerate coccidia oocysts in poultry flocks. It also allows for speciation of coccidia according to the size of their oocysts. The McMaster is a manual technique, which can be tedious and time-consuming. In this study, we present a method for quantification and classification of Eimeria using the image processing program, FIJI ImageJ (ImageJ). We compared 34 litter samples from different poultry houses. Oocysts were loaded and floated into a McMaster chamber, where they were counted manually and by ImageJ. When the software settings were used to count all oocysts without size consideration, statistical differences were found between the two techniques; however, when the parameters were set to identify specific oocyst size and cirularity, no significant statistical differences were found between results from McMaster counting technique and ImageJ. Taking the sum of the individual oocysts sizes (small, medium, and large) provided a total count that was similar to the total count obtained using the manual method. Furthermore, no statistical differences were found in the counts of Eimeria sp. oocysts by either method. However, a small but statistically significant difference was found between counts obtained using the two methods for the medium size oocysts (tentatively classified as E. necatrix, E. precox, and E. tenella together). Overall, automatic counting using ImageJ was demonstrated to be an accurate and rapid method for counting and speciating Eimeria.