Abstract
Free-ranging wildlife are increasingly recognized as potential reservoirs of disease-causing Campylobacter species such as C. jejuni and C. coli. Raccoons (Procyon lotor), which live at the interface of rural, urban, and more natural environments, are ideal subjects for exploring the potential role that wildlife play in the epidemiology of campylobacteriosis. We studied the prevalence and genetic diversity of Campylobacter from live-captured raccoons on five swine farms and five conservation areas in southwest Ontario. From 2011 to 2013, we collected fecal swabs (n = 1,096) from raccoons, and (n = 50) manure pit samples from the swine farm environment. We subtyped the resulting Campylobacter isolates (n = 581) using Comparative Genomic Fingerprinting (CGF) and 114 distinct subtypes were observed, including 96 and 18 subtypes among raccoon and manure pit isolates, respectively. Campylobacter prevalence in raccoons was 46.3%, with 98.7% of isolates recovered identified as C. jejuni. Novel raccoon-specific CGF subtypes (n = 40/96) accounted for 24.6% (n = 143/581) of Campylobacter isolates collected in this study. Our results also show that C. jejuni is readily acquired and lost in this wild raccoon population and that a high Campylobacter prevalence is observed despite transient carriage typically lasting 30 days or fewer. Moreover, although raccoons appeared to be colonized by species-adapted subtypes, they also harbored agriculture-associated genotypes that accounted for the majority of isolates observed (66.4%) and that are strongly associated with human infections. This suggests that raccoons may act as vectors in the transmission of clinically-relevant C. jejuni subtypes at the interface of rural, urban, and more natural environments.
Highlights
Campylobacter species are the second most reported bacterial foodborne pathogen in Canada [1], and campylobacteriosis remains one of the most common enteric illnesses worldwide [2]
The objectives of this study were to: [1] determine the prevalence of Campylobacter in raccoons captured on swine farms and conservation areas; [2] assess the genetic diversity, population structure, and ecology of Campylobacter subtypes observed in raccoons; [3] assess the dynamics of Campylobacter acquisition/loss in individual animals; and [4] compare the subtypes observed in raccoons and human clinical cases to assess the potential role of raccoons in the epidemiology of campylobacteriosis
Prevalence of Campylobacter in the raccoon population under study, which is native to the Grand River Watershed in southwestern Ontario, Canada, was found to be much higher than what has been previously reported for other populations of small to medium-sized wild mammals
Summary
Campylobacter species are the second most reported bacterial foodborne pathogen in Canada [1], and campylobacteriosis remains one of the most common enteric illnesses worldwide [2]. Human infections are primarily caused by two thermophilic species, C. jejuni and C. coli, several additional species have been reported to cause illness [3]. Given that Campylobacter is actively shed in animal feces, environmental sources such as surface waters may become contaminated through use by animals or due to surface runoff [9]. This may lead to increased environmental transmission and dissemination of Campylobacter across different ecological niches, thereby creating additional routes of exposure to humans or other potential hosts [10]
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