Comparison of post-mortem examination, faecal sedimentation, antibody ELISA, and real-time PCR methods in the detection of Fasciola spp. in naturally infected dairy cattle.

Fasciolosis is a food-borne disease affecting livestock worldwide. Improved diagnostic methods for detecting fasciolosis have been introduced; however, limited research has compared these methods. The current study aimed to compare the detection of Fasciola in naturally infected slaughtered dairy cattle using four methods. Blood and faecal samples were collected from slaughtered cattle in three high-throughput abattoirs in the Eastern Cape Province, South Africa, from 2020 through 2021. Post-mortem liver examination was conducted to detect and identify Fasciola spp. Blood from slaughtered carcasses was analyzed using an antibody ELISA to detect Fasciola antibodies, while faecal sedimentation and quantitative real-time PCR (qPCR) were used to detect Fasciola eggs and Fasciola DNA, respectively, in faeces. A binomial Generalized Linear Model (GLM) and Cohen's Kappa test were used to compare the detection rate and determine the level of agreement across the four diagnostic methods. Significant differences (P = 0.0001) across the four diagnostic methods were observed. The highest detection rate was observed using the post-mortem liver examination (94.5%), followed by qPCR (90.4%), ELISA (22.6%), and faecal sedimentation (3.53%) in that order. There was a poor agreement between sedimentation and Ab-ELISA (kappa = -0.105, p = 0.128), sedimentation and post-mortem liver examination (kappa = -0.054, p = 0.163), and qPCR and liver examination (kappa = -0.076, p = 0.341). In conclusion, results from the current study revealed significant differences among the four methods in the detection of Fasciola spp. post-mortem liver examination and qPCR were more reliable, sensitive, and accurate than ELISA and sedimentation methods.