Tuberculosis is on the rise in Canada

On World Tuberculosis Day, March 24, Professor Simon Grandjean Lapierre discusses the new molecular tools to improve treatment and halt transmission being developed at his Université de Montréal lab. For many, tuberculosis evokes images of 19th-century sanatoriums, including many in Quebec. Yet the disease is far from eradicated. In fact, there has been a resurgence since the COVID-19 pandemic.

"We've seen a significant increase in cases on the Island of Montreal since 2023," said Prof. Grandjean Lapierre, a clinical professor in the Department of Microbiology, Infectious Diseases and Immunology at University de Montréal and a researcher at the UdeM-affiliated CHUM Research Center.

Prof. Grandjean Lapierre leads a translational research program focused on tuberculosis control in Canada and abroad, particularly in Madagascar, where the disease is a major public health concern. The program's goal is to ensure that clinical research addresses the real-world needs of clinicians and public health experts by developing new diagnostic tools that enable faster, more effective delivery of treatments and public health interventions.

Still a threat

Tuberculosis is an infectious disease caused by the bacterium Mycobacterium tuberculosis that manifests in two forms: latent infection and active disease. While the latent form causes no symptoms, the active form is highly contagious and can be fatal if left untreated. People who are immunocompromised or living with HIV are particularly at risk of developing the active form.

"Most of the time, the bacterium lies dormant in the body, but it can reactivate even decades later," explained Prof. Grandjean Lapierre. "When this happens, the person typically develops a respiratory illness, although any organ can be affected. It is therefore essential to break the chain of transmission."

Canada saw a steady decrease in the incidence of tuberculosis starting in the 1950s, but recently it has been making a comeback. Not only do communities in the Far North continue to experience outbreaks, but urban centers are not immune.

"It's what we call a 're-emerging' disease," said Prof. Grandjean Lapierre. "At the CHUM, we diagnose between 20 and 40 cases per year."

The increase is linked to a variety of factors: population mobility after borders reopened following the pandemic, precarious living conditions and overcrowding resulting from weakened social safety nets, and rising homelessness. In addition, inadequate screening allows latent infections to go undetected, further fueling the resurgence.

Antibiotic resistance

In his lab, Prof. Grandjean Lapierre and his team are working to design and validate new diagnostic tools. "We're optimizing bacterial DNA sequencing protocols, describing new mutations and validating bioinformatics tools to simplify analysis," he explained.

One avenue of research focuses on the antibiotic resistance tests used to select the appropriate treatment. Currently, these tests are based on bacterial culturing, a slow method that costs precious time before targeted treatment can begin.

Prof. Grandjean Lapierre and his team are therefore developing tests that analyze the bacteria's genetic code to identify mutations that affect antibiotic resistance. This will enable clinicians to quickly select the most effective drug for the specific bacterial strain.

It's an ongoing challenge that has student interns in his lab learning a range of both conventional methods and cutting-edge molecular tools. "Our work is never done because as new drugs are brought to market, new resistance mechanisms emerge," noted Prof. Grandjean Lapierre.

Testing in the field

To evaluate efficacy for tuberculosis control, Prof. Grandjean Lapierre and his team—including Emmanuelle Ametepe, a doctoral student in public health—deployed some of these new molecular tests across communities in Madagascar. After a three-year study involving nearly 46,000 participants, the tests proved superior to microscopy and culturing in accurately diagnosing the disease.

On this side of the Atlantic, where transmission is less active, the team is using whole-genome sequencing of the bacterium to gain a more detailed understanding of transmission dynamics.

"In an environment such as ours, where there is less community transmission, these tools help us identify outbreaks and respond appropriately," explained Prof. Grandjean Lapierre.

Comparing the mutations found in a bacterium isolated in a patient with those of other bacterial strains allows public health teams to better understand transmission chains, accelerate contact tracing, and manage contacts before individuals become ill.

These new tools are not yet in routine use, but Prof. Grandjean Lapierre's team is collaborating with the CHUM, its partner hospitals and the Laboratoire de santé publique du Québec to assess their effectiveness before they are rolled out across Quebec's health care system.

"The challenge lies not only in designing new tools, but also in ensuring they are properly implemented in partnership with clinical settings and public health authorities, so they can support personalized interventions in both clinical and public health contexts," explained Prof. Grandjean Lapierre.

Unfortunately, tuberculosis remains a pressing issue. "If we don't take appropriate public health actions, everyone remains at risk," he concluded.

Provided by University of Montreal