One may be interested in the causative factors behind the observed
correlations. One such factor is co-infection with HIV, a disease more
common in immigrants. Co-infection of HIV and TB is reported by
Brassard et al.4 They report that 5.2% of people with AIDS in the
Province of Quebec have had TB and 5.8% of those with active TB are
HIV positive. They conclude that immigrants from HIV-stricken countries
are significantly more likely to develop TB and that AIDS contributes
significantly to the number of TB cases in the Province of
Quebec. This is consistent with the fact that the most common country
of origin for immigrants with TB in Quebec is Haiti,2 which has the
third highest rate of HIV outside Africa.54 Another factor is poverty and
socioeconomic status. In British Colombia, it was observed that one’s
socioeconomic stratum was an important risk factor for the incidence
of TB.5 Poverty is known to be an issue among indigenous peoples in
Canada. In addition, there is evidence that tuberculosis epidemiology
is linked to vitamin D deficiency55 and thus it may be possible to reduce
the incidence of the disease in at-risk populations with a supplementation
program. Vitamin D deficiency may help explain the disparity
between men and women in Quebec: Selvaraj et al.56 found evidence
that tuberculosis susceptibility is related to a mutation of the vitamin
D receptor in men but not women. Among other factors, the increased
rate of tuberculosis among the Quebec Inuit may be due to vitamin D
insufficiency, due to both the greater latitude of their communities and
due to nutritional insufficiencies.57 This may be a factor explaining
why tuberculosis rates are so much greater in Quebec Inuit than other
Indigenous populations, such as Australian aborigines, who experience
more sunlight.