Use of genotyping based clustering to quantify recent tuberculosis transmission in Guadeloupe during a seven years period: analysis of risk factors and access to health care

International audience ; Background:The present study aimed to characterizeMycobacterium tuberculosispopulation structure and toidentify transmission chains and risk factors by prospective molecular typing in conjunction with conventionalepidemiological investigations in the French overseas department of Guadeloupe.Methods:The study included all the culture-positive TB cases (1 clinical isolate per patient; n = 129) diagnosedbetween a seven year period (April 4th, 1999 to December 31st, 2005). Prospective molecular typing was performedusing spoligotyping and VNTRs, and a subset of 44M. tuberculosisisolates found to be clustered was retrospectivelytyped using 12-loci MIRUs. Data were compared using the SITVIT2 database, followed by analysis of risk factors infunction of clustering of the isolates and available demographic and socioeconomic data.Results:The study sample was characterized by a majority of new cases (87.4%); a moderate proportion of drug-resistance (7.8%); a high level of immigration (51.2% foreign-born) originating from high TB/HIV incidenceneighboring islands such as Haiti or Dominican Republic; lower socioeconomic conditions (70.7% of jobless,average income 824 EUR/month); and a significantly higher proportion of TB/HIV co-infected cases (38.2% vs. 8.5%;p < 0.001), and extrapulmonary disease (18.2% vs. 4.8%;p < 0.02) among migrants as compared to French patients.The study revealed an important delay in access to healthcare with a median delay of 74.5 days between the 1stsymptoms and clinical suspicion of TB. Prospective molecular typing based on spoligotyping and 5-loci VNTRsshowed that evolutionary recent Euro-American lineages predominated in Guadeloupe (91.5% of isolates). Inconjunction with epidemiological data, it allowed to estimate a recent transmission rate of 18.6%, which was closeto the rate of 16.7% estimated using retrospective 12-loci MIRU typing. Although a higher proportion of cases inolder age-group were apparently linked to reactivation; univariate analysis of risk factors ...