Progress towards tuberculosis elimination: secular trend, immigration and transmission

This study aimed to determine to what extent tuberculosis trends in the Netherlands depend on secular trend, immigration and recent transmission. Data on patients in the Netherlands Tuberculosis Register in the period 1993-2007 were matched with restriction fragment length polymorphism (RFLP) patterns of Mycobacterium tuberculosis isolates. Index patients were defined as patients with pulmonary tuberculosis whose isolates had RFLP patterns not observed in another patient in the previous 2 yrs. Among 8,330 patients with pulmonary tuberculosis the isolates of 56% of native and 50% of foreign-born patients were clustered. Of these, 5,185 were included in detailed analysis: 1,376 native index patients, 2,822 foreign-born index patients and 987 secondary cases within 2 yrs of diagnosis of the index case. The incidence of native and foreign-born index patients declined by 6% and 2% per year, respectively. The number of secondary cases per index case was 0.24. The decline of native cases contributed most to the overall decline of tuberculosis rates and was largely explained by a declining prevalence of latent infection. Tuberculosis among immigrants was associated with immigration figures. Progress towards elimination of tuberculosis would benefit from intensifying diagnosis and treatment of latent infection among immigrants and global tuberculosis control.