Impact of the COVID-19 Pandemic on the Reported Incidence of Select Bacterial Enteric Diseases in Canada, 2020

The aim of this study was to describe the impact of the COVID-19 pandemic on reported cases and clusters of select enteric diseases in Canada, for the period of March 2020 to December 2020. Weekly counts of laboratory confirmed cases of Salmonella, Shigella, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes were obtained from laboratory surveillance data. These data were supplemented with epidemiological information on the suspected source of illness, collected for cases identified within whole genome sequencing clusters. Incidence rate ratios were calculated for each pathogen. All data were compared with a prepandemic reference period. Decreases in the number of reported cases in 2020 compared with the previous 5-year period were noted for Salmonella, Shigella, Escherichia coli O157, and non-O157 STEC. Reported number of cases for L. monocytogenes in 2020 remained similar to those of the previous 5-year period. There was a considerable decline (59.9%) in the number of cases associated with international travel compared with a 10% decline in the number of domestic cases. Comparison of reported incidence rates of clustered versus sporadic cases for each pathogen showed little variation. This study represents the first formal assessment of the impact of COVID-19 on reported enteric diseases in Canada. Reported case counts across several pathogens saw notable declines in 2020 compared with prepandemic levels, with restrictions on international travel playing a key role. Additional research is needed to understand how limitations on social gatherings, lock downs, and other public health measures have impacted enteric diseases.