Canadian Wastewater Surveillance Expands to Emerging Public Health Threats: Tam


Plans are underway to filter Canadian sewage to test and measure monkeypox, polio and other potential health threats, the country’s public health official said Friday.

During the COVID-19 pandemic, sewage testing has become a key way to track the spread of the virus, especially as free lab testing for individuals has been phased out for all but a few. in later waves.

Dr Theresa Tam said experts at the National Microbiology Laboratory have now discovered a promising approach to detecting monkeypox in sewage and will use the infrastructure developed during the pandemic to search for it.

“Going forward, this could be part of our monitoring of disease activity going up and down across the country,” Tam told a news conference.

Tam said the method is complicated, but they landed on something that can “probably” be used more widely. How this surveillance fits into the Public Health Agency of Canada’s surveillance efforts on monkeypox is not yet clear.

Monkeypox disease comes from the same family of viruses that cause smallpox, which the World Health Organization declared eradicated worldwide in 1980.

Cases of monkeypox began to appear worldwide in non-endemic countries in May.

This week alone, the number of Canadian cases topped 1,000, although there are early signs the virus may now be spreading at a slower rate, Tam said.

The Public Health Agency of Canada also intends to begin polio testing as soon as possible after US health officials discovered the polio virus in New York City sewage.

The devastating virus was eradicated from Canada in 1994 and until very recently had not been found in the United States since 1993. Cases have recently emerged in Western countries with traditionally high rates of vaccinated people .

A positive case was discovered in New York last month.

The presence of the polio virus in the city’s sewage suggests the virus is likely circulating locally, city, New York state and U.S. federal health officials said Friday.

“We’re already starting to look at what the options are,” Tam said of polio surveillance in Canada.

Polio testing has only just come online in Ontario, said Eric Arts, a professor of microbiology and immunology at Western University.

The COVID-19 pandemic has proven how useful waste can compare to individual testing, he said, especially when it comes to early detection.

“Instead of randomly testing hundreds of thousands of people to see if they’re infected with a specific pathogen, or a pathogen that we don’t even know is circulating, you can just get a sewage sample. and test 100,000 people with one test,” he said.

Wastewater monitoring can also be adapted for other things, she said. Even before the pandemic, Tam said the public health agency was looking for ways to look for antimicrobial-resistant organisms, or superbugs, as they’re often called.

Wastewater detection is still imperfect, however, Tam warned.

“You’re dealing with a mush of a lot of stuff with a lot of DNA, RNA, all kinds of stuff,” Tam said, putting it down politely.

This mush includes countless viruses and viral mutations. Some vaccines, like the oral polio vaccine given in some countries that includes live attenuated virus, can also be mistaken for the real thing in a sewage sample.

“It’s not very easy,” she said.

Different countries use different methods, Tam said, and even in Canada there’s a lot of innovation.

“I think one of the roles of our lab is to then look at the best methods and try to bring standardization and guidance to those tests,” she said.

Laura Osman, The Canadian Press



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