Exploring Food Insecurity as a Risk Factor for Eight Enteric Infections in Ontario, Canada, 2019-2022: Multilevel Ecological Study

Abstract

Food insecurity and foodborne illness are significant public health issues in Canada, associated with poor health, direct healthcare costs, and lost productivity. While previous ecological studies in higher-resource countries have explored the relationship between broad socioeconomic determinants and foodborne infections, none have explored food insecurity as a risk factor for enteric infections. Food insecurity is recognized as a potential intermediary determinant that can influence an individual’s vulnerability and exposure to foodborne illness. This study aimed to identify the magnitude, distribution, and spatial patterns of reported Campylobacter spp., Salmonella spp., Shiga toxin-producing E. coli (STEC), Listeria monocytogenes., Shigella spp., Cyclospora cayetanensis, Giardia duodenalis spp., and hepatitis A virus infections across Ontario, Canada, from January 2019 to December 2022. Additionally, it explored whether age- and sex-adjusted annual pathogen-specific incidence rates were associated with the prevalence of household food insecurity at the Public Health Unit (PHU) level during 2021.

Public Health Ontario’s publicly available surveillance tools were used to collect data on household food insecurity and reported case counts of eight enteric infections for 34 Ontario PHUs. Annual age- and sex-adjusted pathogen-specific incidence rates were calculated for each PHU using direct standardization and were visualized using choropleth maps. Purely spatial, temporal, and space-time high infection rate clusters were identified using retrospective scan statistics, with a Poisson model. Global and local spatial autocorrelation patterns of annual pathogen-specific incidence rates were examined using the Moran’s I spatial statistical method. Fixed and random effects Poisson and Negative Binomial regression analyses were conducted to estimate incidence rate ratios (IRR) for each enteric pathogen and the prevalence of household food insecurity, while controlling for demographic and socioeconomic covariates. A geographically weighted Poisson regression analysis was used to explore whether the association between pathogen-specific incidence rates and household food insecurity differed spatially across PHUs.

Reported cases of all enteric pathogens, except for Listeria monocytogenes, had a noticeable decline after 2019. Campylobacter spp., Salmonella spp., and Giardia duodenalis consistently had the highest incidence rates across PHUs from 2019-2022. Spatial and spacetime analyses showed that Salmonella spp. and STEC high-infection rates mainly clustered in Central- and South-West regions of Ontario. Campylobacter spp., Listeria monocytogenes, Shigella spp., Cyclospora cayetanensis, Giardia duodenalis, and hepatitis A infections were widely distributed across the province. Campylobacter spp., STEC, Listeria monocytogenes, and Cyclospora cayetanensis were the only pathogens to exhibit a temporal pattern, with infections clustering in the warmer months. Two significant space-time clusters of Salmonella spp. and hepatitis A were associated with confirmed outbreaks in Lambton Public Health and Middlesex London Health Unit. In 2021, the prevalence household food insecurity had an inverse association with the incidence rates of Campylobacter spp., STEC, and Giardia duodenalis, with minimal spatial variability of the IRRs across PHUs. No significant associations were observed between household food insecurity and the other enteric pathogens.

Food insecurity may influence the incidence of foodborne illness at an aggregate level. Spatial and temporal clustering of enteric pathogens suggests local and seasonal risk factors could be associated with foodborne illness. Future research should investigate whether the incidence rates of foodborne illness differ among populations experiencing marginal, moderate, and severe levels of food insecurity. The findings from this study could help PHUs develop public health interventions that simultaneously address food insecurity and food safety.