Background: In October 2020, an investigation began in Canada on an outbreak of Salmonella Typhimurium infections of the same strain as a concomitant outbreak in the United States (US) that was linked to pet hedgehogs. The objective of this article is to identify the source of the outbreak, determine if there was a link between the Canadian and US outbreaks and identify risk factors for infection to inform public health interventions.
Methods: Cases were identified through whole genome sequencing of S. Typhimurium isolates. Information was collected on case exposures, including animal contact. Hedgehog and environmental specimens were tested for S. Typhimurium and a trace back investigation was conducted.
Results: There were 31 cases in six provinces, with illness onset dates from June 1, 2017, to October 15, 2020. Median case age was 20 years and 52% were female. Isolates grouped together between 0-46 whole genome multi locus sequence typing allele differences. Of 23 cases with available exposure information, 19 (83%) reported contact with hedgehogs in the seven days prior to symptoms; 15/18 (83%) reported direct contact and 3/18 (17%) reported indirect contact. Trace back investigation did not identify a common source of hedgehogs but uncovered an industry with a complex distribution network. The outbreak strain was detected in samples collected from a hedgehog in one case's home and from a hedgehog in a Québec zoo.
Conclusion: Direct and indirect contact with hedgehogs was identified as the source of this S. Typhimurium outbreak. Public health communications aimed to increase awareness about the risks of zoonoses from hedgehogs and shared key hygienic practices to reduce disease transmission.
Keywords: S. Typhimurium; enteric; hedgehog; outbreak; salmonella; zoonotic.
Public Health Agency of Canada, 2022.