Abstract
BackgroundMontreal is Canada's second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000. The objectives of this study were to describe the epidemiology of TB among homeless persons in Montreal and assess patterns of transmission and sharing of key locations.MethodsWe reviewed demographic, clinical, and microbiologic data for all active TB cases reported in Montreal from 1996 to 2007 and identified persons who were homeless in the year prior to TB diagnosis. We genotyped all available Mycobacterium tuberculosis isolates by IS6110 restriction fragment length polymorphism (IS6110-RFLP) and spoligotyping, and used a geographic information system to identify potential locations for transmission between persons with matching isolates.ResultsThere were 20 cases of TB in homeless persons, out of 1823 total reported from 1996-2007. 17/20 were Canadian-born, including 5 Aboriginals. Homeless persons were more likely than non-homeless persons to have pulmonary TB (20/20), smear-positive disease (17/20, odds ratio (OR) = 5.7, 95% confidence interval (CI): 1.7-20), HIV co-infection (12/20, OR = 14, 95%CI: 4.8-40), and a history of substance use. The median duration from symptom onset to diagnosis was 61 days for homeless persons vs. 28 days for non-homeless persons (P = 0.022). Eleven homeless persons with TB belonged to genotype-defined clusters (OR = 5.4, 95%CI: 2.2-13), and ten potential locations for transmission were identified, including health care facilities, homeless shelters/drop-in centres, and an Aboriginal community centre.ConclusionsTB cases among homeless persons in Montreal raise concerns about delayed diagnosis and ongoing local transmission.
Highlights
Montreal is Canada’s second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000
Any physician who makes a diagnosis of active TB and any laboratory that identifies Mycobacterium tuberculosis (M. tuberculosis) from a clinical specimen must report the case in nominal form to the public health department
Incidence of TB We identified 20 cases of TB in homeless persons, out of a total of 1823 cases of active TB reported in Montreal from January 1, 1996 to September 11, 2007
Summary
Montreal is Canada’s second-largest city, where mean annual tuberculosis (TB) incidence from 1996 to 2007 was 8.9/100,000. Homeless persons are an important risk group for TB, even in low incidence settings. Outbreaks among homeless persons have been documented in many North American cities over the past two decades [3,4,5,6]. There have been anecdotal reports of TB among homeless persons in Montreal[11,12]. As this can have significant consequences for the wider community, we sought to describe the epidemiology of TB among homeless persons in Montreal from 1996 to 2007, including the extent of transmission within this group, and to and/or from the non-homeless population
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