One graduate student’s wild goose chase
It all started with an email to a former professor of mine at the University of Guelph. Fast-forward to one year later, and I was standing in a local park in Guelph, ON, secretly hoping that the Canada goose standing in front of me would poop. Here I was, collecting samples for a Master’s project examining the carriage of various bacteria in the feces of these birds.
Canada geese have become quite the fixture in many of our local parks here in Ontario, and also across Canada. Love them or hate them, the geese are here to stay. Most geese are resident birds, meaning that they no longer migrate south for the winter. This is probably related to an increase in food sources, in combination with milder winters. Many of these resident birds can be seen feeding on leftover grain on agricultural land. Migratory birds, however, travel as far south as Mexico for the winter months. With some geese travelling long distances, and their close contact with humans and livestock, there are a number of questions surrounding the role of Canada geese as a potential source of harmful microorganisms to other animals, including humans.
Our research examined the potential for Canada geese to harbor and potentially transmit microorganisms such as Salmonella and Campylobacter, which are major causes of foodborne illness in Canada. In addition, we examined antimicrobial resistance, a major threat to human health across the globe, using E. coli as an indicator species (i.e., not necessarily harmful in and of itself).
To explore the issue, we collected samples from diagnostic birds submitted to the CWHC, hunted birds harvested by a local hunting group, and fecal swabs from live birds in parks and agricultural areas in southern Ontario. Overall, we found low levels of these microorganisms, with 11.2% of birds positive for Campylobacter, and 0% of birds positive for Salmonella. Antimicrobial resistance in E. coli was identified in 7.9% of birds (at least one class of antimicrobials from the testing panel used by the Canadian Integrated Program for Antimicrobial Resistance Surveillance). Only 5.6% of all E. coli were resistant to multiple classes of antimicrobials. Compared to a handful of studies looking at Canada geese in the United States, we have identified relatively low proportions of geese carrying these microorganisms.
Unfortunately, we cannot rule these birds out as a potential source of harmful microorganisms for humans and livestock. The environmental transmission cycles of these microorganisms are extremely complex. This is, however, an important first step to better our understanding of the role of Canada geese in the transmission of these bacteria in the environment. Moving forward, our next step will be to investigate the potential transmission of Campylobacter between Canada geese and other animals, by comparing Campylobacter subtypes isolated from geese to those identified in human and livestock Campylobacter infections. And so the wild goose chase continues…