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. 2003 Aug 13:3:18.
doi: 10.1186/1471-2334-3-18.

Conventional and molecular epidemiology of tuberculosis in Manitoba

Kym S Blackwood  1 , Assaad Al-Azem, Lawrence J Elliott, Earl S Hershfield, Amin M Kabani
Affiliations

Conventional and molecular epidemiology of tuberculosis in Manitoba

Kym S Blackwood et al. BMC Infect Dis. .

Abstract

Background: To describe the demographic and geographic distribution of tuberculosis (TB) in Manitoba, thus determining risk factors associated with clustering and higher incidence rates in distinct subpopulations.

Methods: Data from the Manitoba TB Registry was compiled to generate a database on 855 patients with tuberculosis and their contacts from 1992-1999. Recovered isolates of M. tuberculosis were typed by IS6110 restriction fragment length polymorphisms. Bivariate and multivariate logistic regression models were used to identify risk factors involved in clustering.

Results: A trend to clustering was observed among the Canadian-born treaty Aboriginal subgroup in contrast to the foreign-born. The dominant type, designated fingerprint type 1, accounts for 25.8% of total cases and 75.3% of treaty Aboriginal cases. Among type 1 patients residing in urban areas, 98.9% lived in Winnipeg. In rural areas, 92.8% lived on Aboriginal reserves. Statistical models revealed that significant risk factors for acquiring clustered tuberculosis are gender, age, ethnic origin and residence. Those at increased risk are: males (p < 0.05); those under age 65 (p < 0.01 for each age subgroup); treaty Aboriginals (p < 0.001), and those living on reserve land (p < 0.001).

Conclusion: Molecular typing of isolates in conjunction with contact tracing data supports the notion of the largest ongoing transmission of a single strain of TB within the treaty-status population of Canada recorded to date. This data demonstrates the necessity of continued surveillance of countries with low prevalence of the disease in order to determine and target high-risk populations for concentrated prevention and control measures.

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Figures

Figure 3
Figure 3
Tuberculosis incidence rates by age group and origin, 1992–1999.
Figure 1
Figure 1
Geographic distribution of tuberculosis patients in Manitoba, 1992–1999. Top chart represents rural Manitoba, in contrast, the bottom depicts urban Manitoba.
Figure 5
Figure 5
Distribution of the top five prevalent fingerprint types by (a) population subgroup and (b) geographic subgroup, 1992–1999.
Figure 4
Figure 4
Clustering of fingerprint patterns for (a) population subgroups, (b) geographic subgroups, 1992–1999.
Figure 2
Figure 2
Reported new active and relapsed tuberculosis cases and incidence rate per 100,000 – Canada: 1928–1998.
See this image and copyright information in PMC

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