Rapid detection of Haemophilus parasuis using cross-priming amplification and vertical flow visualization

Haemophilus parasuis infection is of considerable economic importance in the swine industry due to high morbidity and mortality in naive swine populations. Accurate detection and identification of the causative agent are difficult, yet necessary, for disease control. In this study, a simple and rapid method of cross-priming amplification (CPA) with a vertical flow (VF) visualization strip was established to detect H. parasuis. The reaction can specifically identify 15 serovar reference strains and 57 clinically isolated strains of H. parasuis, with a detection limit of 14 CFU. The performance of the CPA-VF assay was evaluated and compared with that of species-specific PCR by testing 62 clinical culture-positive specimens of H. parasuis. The entire process, from specimen processing to analysis of the results, can be completed in 2 h without a complicated apparatus. The convenience and speed of the CPA-VF assay in this study make it a suitable choice for epidemiological investigation and point-of-care testing (POCT) for H. parasuis infection.