[Border-crossing source tracing in tuberculosis via DNA fingerprint technique].

Objective: Description of the value of modern DNA analysis ('restriction fragment length polymorphism'; RFLP) as a method for mapping tuberculosis transmission.

Design: Descriptive.

Setting: Social Health Service Noord-Friesland, the Netherlands.

Method: A large-scale tuberculosis investigation was conducted in Harlingen in 1993 when a 2,5 year old patient with tuberculous meningitis was reported. Source tracing and contact tracing extended from Harlingen to the west of the Netherlands and even abroad. Modern DNA analysis (RFLP) was used to map the tuberculosis transmission.

Results: A total of 6519 persons were screened and 276 infected people were identified, of whom 49 were suffering from active tuberculosis. RFLP analysis showed in 27 of them a 'Harlingen' type Mycobacterium tuberculosis DNA pattern identical to that of the index patient. The source patient was finally traced in England. By the end of 1994 3 more patients were found with the same DNA pattern; their relation with the source patient and the outbreak of tbc remained unrevealed.

Conclusion: The Harlingen outbreak was extensive and characterized by time-consuming source tracing. Modern DNA analysis proved to be a very useful instrument in identifying the source case.