Evaluation of commercial rapid tests for fast and on-site detection of high-pathogenicity avian influenza H5 virus in poultry.

Since 2016, numerous outbreaks of high-pathogenicity avian influenza (HPAI) have occurred on poultry farms in Europe. Samples from suspected outbreaks are investigated using PCR at the national reference laboratories (NRLs) to detect the presence of the influenza virus. In the Netherlands, on occasion, multiple poultry farms needed to be investigated, sampled, and prioritized for testing at the NRL. For these and other situations, on-site pre-screening with rapid diagnostic tools could, in addition to visual inspections, provide additional information to support decisions on prioritization. This study focuses on lateral flow tests as rapid on-site diagnostic tools. Upon a review of available tests, five were selected and evaluated. Rapid tests from Anigen, Biopanda, and Clungene had the best limit of detection and could detect all hemagglutinin subtypes (H1-16). Testing respiratory and cloaca swabs from chickens and ducks experimentally infected with HPAI H5 virus revealed a relationship between the results of rapid tests and the sample's viral load (Ct value of PCR). The Clungene rapid test had a diagnostic sensitivity (DSe) > 71% when Ct values were < 25, whereas the DSe was compromised when Ct values were > 28. A statistical model was built to describe this relationship and was applied to historic PCR data of samples from recent HPAI H5 outbreaks in the Netherlands. The predicted DSe of the Clungene rapid test was > 81% for respiratory and cloaca samples from ducks, turkeys, and chickens. These results indicate that rapid tests may serve as additional diagnostic tools for pre-screening samples suspected of avian influenza.IMPORTANCEThis study was performed to investigate whether rapid tests could serve as additional diagnostic tools for pre-screening samples suspected of avian influenza. Several rapid tests were acquired and tested for their analytical sensitivity. With a subset of these, swabs from chickens and ducks experimentally infected with avian influenza were investigated. A relationship of the test results with the viral load was modeled, and by using historic data from recent H5N1 outbreaks in The Netherlands, the predicted diagnostic sensitivity of a rapid test was > 81%. This suggests that rapid tests could have potential as supportive diagnostic tools in outbreak situations with avian influenza, but PCR by the national reference labs remains essential and obligatory for detection of avian influenza.