INFLUENZA A VIRUSES OF SWINE IN WESTERN CANADIAN PIGS AND PEOPLE

Influenza A viruses (IAV) are well-known for their zoonotic potential, and the health and economic threats they pose to humans and pigs. The complexity of influenza virus ecology involving genetically variant viral strains and several natural hosts means that the virus continuously challenges the host-species barrier. Surveillance of IAV is essential as it provides helpful information that can lead to a better understanding of the behavior of the virus at the animal-human interface, the risk factors and the key genetic changes that allow the virus to cross the species barrier. The research aimed to compare the suitability of samples collected for the detection of IAV in swine and to identify the epidemiological and viral factors that might play a fundamental role in the human-swine interface of transmission. The suitability of three types of samples for the detection of IAV in pigs, nasal swabs (NS), oral fluids (OF) and oral swabs (OS), was compared. IAV Matrix gene PCR results showed NS were the most effective method of IAV detection in swine. Compared to NS, OS had a relative sensitivity of 43.6% to 43.8% and relative specificity of 99.3% to 100%. The relative sensitivity and specificity of OF was 57.1% and 95.5%, respectively. Furthermore, the degree of agreement between NS and the other two samples was moderate (k = 0.531-0.583, p < 0.001). Human-swine transmission was evaluated through a pilot project consisting of active surveillance in both swine workers and pigs from 11 farms in Western Canada. Nasal swabs, OS, and surveys assessing flu-like symptoms were collected from 26 swine workers and results were compared with Matrix real-time reverse transcriptase PCR (RT-qPCR) results from swine nasal swabs. There was no statistically significant correlation between the clinical symptoms in humans and the RT-qPCR results from swine samples. However, the IAV Matrix gene PCR results from the NS and OS of the swine workers had a very weak correlation with the results found in swine (r = 0.182-0.200, p = 0.024- 0.040). Transmission among species was not confirmed, but samples with suspect results from human samples coincided with positive swine pool results and the presence of an Alpha H1N2 virus in 4 farms, which is suggestive of a common link between humans and pigs for IAV