Factors associated with the high tuberculosis case rate in an urban area

The Rotterdam region, the Netherlands, 1995-2006.

To identify factors associated with the high tuberculosis (TB) case rate in an urban area.

Municipalities were divided into urban and semi-urban/rural municipalities. We compared the characteristics of TB cases and stratified case rates according to age group, immigrant status and place and time of infection between the two areas.

The TB case rate in urban municipalities was 3.8-fold higher than in semi-urban/rural municipalities. After stratification for country of birth, the rate ratios were lower (1.7 for immigrants and 2.8 for non-immigrants). Immigrants had most frequently acquired their infection abroad (47% of urban and 62% of semi-urban/rural immigrant cases). In 40% of urban cases and 27% of semi-urban/rural cases, the infection was recently acquired in the Netherlands, translating into a 5.7-fold higher recent transmission case rate for the urban population.

The high urban TB case rate was related to the high proportion of urban immigrants who frequently reactivated an infection acquired abroad. Recent transmission also contributed to a substantial part of the TB caseload in urban municipalities among both urban immigrants and non-immigrants. The authors propose a package of targeted interventions to address the identified factors associated with the high urban TB case rate.