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.