Use of DNA fingerprinting in international source case finding during a large outbreak of tuberculosis in The Netherlands.

SETTING: Tuberculosis outbreak in a low prevalence country. OBJECTIVE: Description of an international source tracing process in which restriction fragment length polymorphism (RFLP) analysis played an essential role. DESIGN: In 1993 a large scale source tracing process was initiated in Harlingen, a harbour town in the north of The Netherlands, after a child with tuberculous meningitis was reported for which no source could be identified. Traditional contact tracing followed the detection of sources of infection. RFLP was used to map the tuberculosis transmission and identify the source case. RESULTS: The investigation extended from the north to several places in the west of The Netherlands. In total 6519 persons were screened; there were 276 infections, among which 49 cases of active tuberculosis were identified. RFLP analysis of Mycobacterium tuberculosis isolates from all 28 culture positive patients showed the 'Harlingen' type DNA fingerprint. After 5 months source tracing led to the identification of the source case in the United Kingdom. Up to June 1996 altogether 37 patients (The Netherlands 28; the UK 7; Surinam 1; Morocco 1) were found to have isolates with the Harlingen type DNA pattern. Despite a thorough evaluation, in 5 of the 37 patients no relation to the source case or the outbreak in Harlingen could be established. CONCLUSION: RFLP typing proved a very useful instrument in guiding the process of international source tracing and contact investigation.

[Border-crossing source tracing in tuberculosis via DNA fingerprint technique]. / Grensoverschrijdende bronopsporing bij tuberculose door DNA-'fingerprint'-techniek.

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.