The similar slope of the regression lines indicates that
ecologic data on the incidence of TB in the country of
birth can provide useful information on the risks of
TB in migrant groups, and that this does not vary significantly
between two migration receiving countries.
Although the rate of TB in migrants in Australia and
Canada is predominantly lower than the estimated
incidence of TB in their respective countries of birth,
the risk of TB among migrants in Australia and Canada
is highly correlated at an ecologic level. The
importance of the incidence of TB in the country of
birth to the incidence of TB among migrants at an
individual level has been described previously,4,9 and
our findings suggest that there is unlikely to be an
additional group-level risk factor for TB among
migrants as important as the incidence of TB in the
country of birth.
The association betwe