Amid Canada’s largest measles outbreak in more than a decade, experts say this COVID-era tool could help

Canada is currently facing its largest measles outbreak in more than a decade, with over 500 cases reported. Health experts are now suggesting that a COVID-era tool, wastewater surveillance, could help in containing the spread of the virus.

Wastewater surveillance involves testing sewage samples for viral pathogens and was widely used during the COVID-19 pandemic to track the spread of the virus. The data gathered from wastewater surveillance helped health officials map out COVID-19’s path and predict the trajectory of cases, making it a critical public health tool.

Experts believe that leveraging regional wastewater surveillance could be instrumental in containing the current measles outbreak in Canada. However, public health officials are not actively utilizing this tool to test for measles. Ontario, a current hotspot for measles cases, even scaled back its wastewater surveillance program last summer.

The Public Health Agency of Canada (PHAC) has a wastewater monitoring dashboard that compiles data from multiple sites across the country, but it currently does not track the measles virus. PHAC tracks weekly measles case counts and publishes them online but has no plans for additional monitoring through wastewater.

Measles, like COVID-19, can be spread by asymptomatic individuals, making reported cases likely an underestimate. Wastewater surveillance could detect areas where the measles virus is spreading and enable public health officials to implement targeted measures such as increased vaccination or education campaigns.

Mike McKay, director of the Great Lakes Institute for Environmental Research in Windsor, Ontario, has been testing wastewater for COVID-19 and other viruses. His team has been asked to test for measles by health officials in Detroit and southwestern Ontario. However, PHAC has not requested measles testing from McKay.

One challenge with testing for measles in wastewater is the need for an additional step due to the live-attenuated vaccine used for measles. This requires further sequencing to differentiate between vaccine virus shedding and actual virus presence.

Despite the potential benefits of wastewater surveillance, there are few testing sites across Canada reporting information. More testing sites are needed to make this tool truly effective. The current measles outbreak in Ontario, linked to a large gathering with Mennonite communities from New Brunswick, highlights the importance of proactive measures like wastewater surveillance.

In conclusion, wastewater surveillance could be a valuable tool in combating measles outbreaks, especially in areas with under-immunized populations. Public health officials should consider expanding wastewater monitoring efforts to better track and contain infectious diseases like measles.