Tuberculosis (TB) among migrants to Canada is limited to those from a small handful of countries, calling into question Canada's practice of screening all new arrivals, according to a recent study in the Canadian Medical Association Journal.
The study linked the Citizenship and Immigration Canada records of almost a million people who arrived in Ontario between 2002 and 2011 with the Ontario Ministry of Health and Long-Term Care's reportable disease database for the same time period (CMAJ, September 29, 2015).
Over the 10-year study period, physicians diagnosed more than 6,000 cases of TB in Ontario; of these patients, nearly 90% were born outside of Canada. This finding demonstrates the importance of having an effective system to track TB in new immigrants, said lead author Dr. Kamran Khan, an infectious disease specialist at St. Michael's Hospital in Toronto.
Even though Canada requires all new immigrants to undergo chest x-rays to screen for active tuberculosis, the researchers found that 87.3% of active cases came from just six countries: Afghanistan, China, India, Pakistan, the Philippines, and Vietnam. The x-rays didn't show a single case of active TB in immigrants from 179 other countries.
In an era when forms of TB are becoming virtually untreatable, it is essential to better direct healthcare resources and apply them where they are most needed, Khan said. This means checking immigrants' birth country, their immune system function, and whether they applied for residency from overseas or within Canada before requesting a TB test.
