Wastewater-based surveillance of hepatitis A virus across municipalities and neighbourhoods in Alberta, Canada

BACKGROUND: Hepatitis A virus (HAV) infection is infrequently diagnosed in Canada, and little data are available regarding its epidemiology. Transmitted fecal-orally, HAV is an ideal candidate for wastewater-based surveillance (WBS). We set out to characterize HAV using WBS in a low-prevalence setting. METHODS: This observational study was conducted in the province of Alberta, Canada. Weekly composite wastewater samples were collected from eight municipalities (populations 7909-1,306,784), and eight neighbourhoods within Calgary, the largest city. HAV genomic material was quantified using RT-qPCR targeted on VP1 and sequenced at the VP1/2A junction. HAV case data from Alberta's Public Health Laboratory and population demographics from census data were correlated with wastewater HAV burden. RESULTS: Between July and December 2023, low levels of HAV were detected in wastewater from 50% of the municipalities and 50% of urban neighbourhoods (with 15.4% and 8.3% of samples testing positive, respectively). Wastewater HAV levels correlated with clinical HAV prevalence in larger communities. For genotyped clinical cases, wastewater with a matching VP1/2A sequence within a two-week period was observed for 8/9 episodes (median 6.42 days). Wastewater-measured HAV associated with population size, population density, and immigration from HAV endemic areas. CONCLUSION: HAV was detectable in wastewater of both municipalities and neighbourhoods within a low prevalence setting. Wastewater HAV was associated with population metrics and socioeconomic factors, including immigration. WBS data correlated strongly with clinical disease revealing a minimal burden of undiagnosed infections. This demonstrates the feasibility of HAV WBS and its potential as a public health tool in non-endemic settings.