Tuberculosis experts have a keen interest in newcomers to Canada.
Immigrants are more likely to get sick with TB than others. In recent years, they’ve accounted for two-thirds of active cases in the country.
That’s why health researchers in B.C. and other provinces are looking for ways to enhance detection of newcomers in danger of becoming ill with the sometimes fatal disease that typically affects the lungs.
“What we’re trying to do is figure out who would be the most high-risk populations and high-yield populations to screen,” Dr. James Johnston told the Georgia Straight in a phone interview.
Johnston is a TB physician with the B.C. Centre for Disease Control. He is leading a team of health experts who are studying ways to improve testing of foreign-born residents in the province.
People with active TB infection aren’t allowed into Canada. They have to get well before they’re given a visa. Immigration applicants with a history of treated TB, or whose chest X-ray shows abnormalities, can come in but are placed under medical surveillance. “The problem is, that process only highlights about two percent of people who arrive to Canada,” Johnston said.
Medical tests prior to departure aren’t designed to detect the disease in its latent form, which could develop into active TB later on.
The need for additional screening programs was underscored in the latest edition of the Canadian Tuberculosis Standards, released in February 2014.
“Only a small proportion of all cases of active TB diagnosed in the foreign-born after arrival in Canada are detected during the immigration post-landing surveillance program,” stated the document, produced jointly by the Public Health Agency of Canada and the Canadian Thoracic Society, the medical arm of the Canadian Lung Association.
The paper noted that 66 percent of the 1,577 reported cases of active TB in 2010 occurred among immigrants. It also noted that newcomers have a 13-fold greater incidence of TB than nonaboriginal Canadian-born residents. In certain subgroups of immigrants, the rates are 500 times greater.
Johnston’s research team includes Jennifer Gardy, an assistant professor at the UBC school of population and public health.
According to Gardy, about 300 people in B.C. are diagnosed with active TB each year; about 200 of them are immigrants.
“Typically, these are individuals who arrive in Canada with the latent infection and then, for some reason, their infection wakes up,” Gardy told the Straight in a phone interview.
Gardy noted that pressures on the immune system caused by stress associated with moving to a new country, as well as diseases such as diabetes, render immigrants vulnerable to active infection.
According to the B.C. Strategic Plan for Tuberculosis Prevention, Treatment, and Control, African countries have the highest incidence rates of TB. First released in 2012, the document also indicates that the majority of cases worldwide are found in Asia, with China, India, Philippines, Indonesia, Bangladesh, and Pakistan accounting for almost half.
The province’s plan seeks to halve the number of active TB cases within a decade. It also aims to cut by half TB’s prevalence in three high-risk populations: immigrants, aboriginal people, and marginalized individuals such as the homeless.
Until TB is eliminated globally, it will remain a concern for Canada.
“TB anywhere is TB everywhere,” Gardy said. “It’s only a matter of time before the very scary [drug-]resistant infections arrive on our doorstep. So even though it’s not a huge burden in British Columbia, it is something that we should all be thinking about.”