Analysis of the Population Structure of Mycobacterium tuberculosis in Ethiopia, Tunisia, and the Netherlands: Usefulness of DNA Typing for Global Tuberculosis Epidemiology

The genetic heterogeneity among Mycobacterium tuberculosis isolates from 501 patients in Ethiopia, Tunisia, and the Netherlands was compared by analysis of DNA polymorphism driven by insertion element IS6110. The percentage of isolates displaying two or more identical patterns differed greatly in the three countries : It was highest among Tunisian isolates and lowest in Dutch isolates. In contrast to isolates from Dutch subjects infected with M. tuberculosis, the majority of strains from Ethiopia and Tunisia were from a few families of genetically highly related strains. Furthermore, little overlap was observed among isolates from the three countries, indicating strict isolation of the bacterial reservoirs in the countries. A few strains from the Netherlands matched strains from Ethiopia and Tunisia. Those strains were invariably isolated from refugees, immigrants, or persons who visited Ethiopia or Tunisia.