Background and objectives: Between 1998 and 2000, approximately 525 Tibetan people previously living in the United States claimed refugee status in Canada, many of whom were referred to our centers for completion of tuberculosis (TB) screening. We reviewed TB-related outcomes in this cohort, to compare our experience with previously published work, and to assess follow-up after a stay in a low-incidence region.
Methods: We performed a retrospective study of all patients of Tibetan origin assessed at our centers (St. Michael's Hospital and West Park Healthcare Centre, both in Toronto) for completion of TB screening, referred because of abnormal chest radiographic findings or positive tuberculin skin test (TST) result. We compared rates of active and drug-resistant TB in our cohort with local and national rates, as well as those previously published in similar groups.
Results: One hundred eighty-nine individuals were referred to us for assessment, and 181 records were available for review. The mean duration of stay in Canada prior to presentation was 2.6 months, after having spent a mean of 11 months in the United States. Thirty-two percent of patients gave a history of previous TB, and 97% were TST positive. Culture-positive TB was diagnosed in 24 patients (13%, 4,571 per 100,000), 12 patients had at least one drug resistance (50% of cases), and 4 patients were resistant to at least isoniazid and rifampin (multidrug resistant, 17% of cases).
Interpretation: People from highly TB endemic areas retain a very high risk of active TB and drug resistance, despite an intervening period in a low-prevalence country. It is important to maintain a high degree of suspicion for TB in all people from high-incidence areas. Treatment of all cases of latent TB infection or ongoing medical surveillance is likely justified in this population.