ANALYSIS OF TUBERCULOSIS TRANSMISSION BETWEEN NATIONALITIES IN THE NETHERLANDS IN THE PERIOD 1993-1995 USING DNA-FINGERPRINTING

Immigration from high prevalence areas may contribute to an increased risk of tuberculosis in Europe. This study aimed at quantifying transm ission of tuberculosis between and within nationalities among resident s of the Netherlands, DNA ''fingerprints,'' on the basis of restrictio n fragment length polymorphism using marker IS6110, were made of all M ycobacterium tuberculosis isolates in the Netherlands from January 199 3 through June 1995, Clusters were defined as groups of patients that had isolates with identical fingerprints. It was assumed that the prob ability of a patient being the source of a cluster was proportional to the incidence rate of potential sources times the probability that a potential source would give rise to a cluster, The transmission index was defined as the average number of secondary cases of infectious tub erculosis caused directly or indirectly through recent transmission by a single potential source case and was used to estimate the effective reproductive rate associated with recent transmission, R-e(FAST). Amo ng a total of 623 Dutch tuberculosis cases, 17% (95% confidence interv al 9-25%) of cases were attributable to recent transmission from a non -Dutch source. The transmission index varied strongly by nationality, and was highest among the Surinamese (1.3), Moroccan (0.8), and Turkis h (0.8) populations; R-e(FAST) was 0.26, Aggregation of tuberculosis c ases of given nationalities within clusters was most pronounced among recent immigrants from Somalia and (ex-) Yugoslavia, The authors concl ude that differences in transmission between subpopulations can be qua ntified and may be used to evaluate and direct tuberculosis control.