INFLUENZA A VIRUSES OF SWINE IN WESTERN CANADIAN PIGS AND PEOPLE
Date
2018-08-30
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
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.
Description
Keywords
Influenza A virus, swine, human, surveillance
Citation
Degree
Master of Science (M.Sc.)
Department
Veterinary Pathology
Program
Veterinary Pathology