Selected zoonotic pathogens and diseases from Ontario identified at the AHL in 2023
Tanya Rossi
Animal Health Laboratory, University of Guelph, Guelph, ON.
AHL Newsletter 2024;28(1):12
The term ‘One Health’, “an integrated, unifying approach to balance and optimize the health of people, animals and the environment”1, is a relatively new one in medicine, however the contribution of veterinarians to public health dates back 100s of years. This contribution has taken many forms, including using comparative physiology and anatomy to further human health, informing policies involving food safety and ecosystem health, and detection of zoonotic pathogens, among others. AHL participates in many of these initiatives, but our primary contribution is in the surveillance and annual reporting of zoonotic pathogens identified at our laboratory (Tables 1 and 2).
Case numbers for most zoonotic pathogens isolated or identified by the AHL in 2023 are relatively unchanged from the previous year, however some changes were identified. After a 4-fold increase from 2021 to 2022 Blastomyces dermatitdis cases have decreased again in canines from 13 in 2022 to 3 in 2023. Avian West Nile virus positives have increased again this year, rising from 11 in 2021 and 26 in 2022 to 50 in 2023. This increase is primarily in wild avian species. Similar increases occurred in Eastern Equine Encephalitis virus positives in equines, and in positive serology submissions for Borrelia burgdorferi in canines and equines. These changes in vector-borne disease may reflect changes in vector populations and distribution that should be investigated further2,3. Isolation of Methicillin-resistant S. pseudintermedius (MRSP) in canines has also increased in 2023.
The percentage of animals identified as positive for leptospirosis was roughly unchanged in 2023 in cattle, equines, and dogs, and the total number of submissions tested was about the same as 2022. The percentage of positive leptospirosis cases and total submissions tested decreased in swine. These are numerator data reliant upon submission biases to the diagnostic laboratory and cannot be regarded as population prevalence estimates. They do not take into account vaccination status, as all except horses may be routinely vaccinated for leptospirosis. Monitoring programs are not included. Brucella canis results shown are positive on the 2ME-RSAT.
Table 1. Number of cases for selected zoonotic pathogens isolated and/or identified at the AHL, 2023.
*Cases may include research samples
Table 2. Leptospira spp. seropositive, IHC-positive, or PCR-positive cases identified at the AHL, 2023.
References
1. Adisasmito WB, Almuhairi S, Behravesh CB, Bilivogui P, Bukachi SA, et al. One Health: A new definition for a sustainable and healthy future. PLoS Pathog 2022;18(6):e1010537.
2. Levy S. Northern trek: The spread of Ixodes scapularis into Canada. Environ Health Perspect 2017;125(7):074002.
3.Paz S. Climate change impacts on West Nile virus transmission in a global context. Philos Trans R Soc Lond B Biol Sci 2015;370(1665):20130561.