Field performance of a point-of-care PCR platform for the detection of influenza A virus in growing pigs

Point-of-care (POC) testing involves conducting diagnostic assays near patients to enable rapid decision-making and timely intervention. To date, evaluation of POC devices under field conditions in veterinary medicine has been limited. The objective of this study was to describe the use and performance of a POC system in the field and with varying sample conditions using influenza A virus in swine. Seventy oral fluid samples were collected from ten swine farms and aliquoted into five treatments: portable PCR performed on farm (FARM), while driving (RIDE), after 24 h incubation at room temperature (RT), on ice (ICE), and as a gold standard, samples were also submitted for testing at the Ohio Animal Disease Diagnostic Laboratory (LAB). Influenza A virus was detected at least in one oral fluid sample for six out of the ten farms sampled according to gold standard results; within-herd prevalence in positive farms varied from 16.7 to 100.0%. POC system's Ct values were statistically associated with the gold standard results. POC tests showed high specificity, with median estimates ranging from 0.954 to 0.958 and 95% credible intervals (CrIs) consistently above 0.91. Sensitivity of POC tests varied more substantially, with the lowest observed in the ICE setting (median 0.805; 95% CrI: 0.607-0.945) and the highest in the RT setting (median 0.926; 95% CrI: 0.766-0.995). Our study showed that the POC PCR system was a promising method for on-site diagnostic testing, providing results consistent with official laboratory results.