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National audience; Leptospirosis is a neglected disease which affects all tropical regions, particularly South America and the Caribbean. Its incidence and case-fatality rates are poorly known, and probably highly underestimated. In order to estimate the real incidence of leptospirosis in the French West Indies, an incidence study was performed in 2011 using the three prevailing available biological tests for diagnosis: Microscopic Agglutination Test (MAT), IgM ELISA and PCR. The study investigated inpatients as well as outpatients, and used active case ascertainment from data provided by a general practitioners’ sentinel network.The incidence of leptospirosis was estimated respectively at 69 and 61 annual cases per 100,000 inhabitants respectively in Guadeloupe and Martinique, representing an incidence 100 times higher than in Mainland France for the study period. The results also show that using PCR-real time for diagnosis has allowed identifying cases many more cases than that would not have been detected without having recourse to this test. It also contributes to early detection of the disease, reducing the risk of complications due to leptospirosis through the prescription of an antibiotic therapy.It has also been possible to describe the epidemiology of the disease in terms of severity, demographic characteristics and seasonal patterns. Besides, these results support the relevance of developing an integrated management strategy for surveillance, prevention and control of the disease in the French West Indies.; La leptospirose est l'une des maladies dites négligées des pays du Sud, en particulier en Amérique latine et dans la Caraïbe. Son incidence réelle et sa létalité sont incertaines, cette dernière étant probablement élevée. Afin d'estimer l'impact sanitaire réel de la maladie aux Antilles françaises, une étude d'incidence a été conduite en 2011, en mettant en oeuvre l'ensemble des outils diagnostiques aujourd'hui disponibles : le test de micro-agglutination (MAT), la sérologie Elisa IgM et la PCR. Cette étude a pris en compte non seulement les patients hospitalisés mais également, grâce aux réseaux de médecins généralistes sentinelles, les patients ambulatoires pris en charge par leur médecin traitant. L'incidence de la leptospirose a été estimée à 69 et 61 cas annuels pour 100 000 habitants, respectivement en Guadeloupe continentale et en Martinique, soit une incidence plus de 100 fois supérieure à celle de la métropole à la période de l'étude. Les résultats montrent également que l'accès au diagnostic par PCR conduit à un nombre de cas aux Antilles très largement supérieur à celui dénombré antérieurement ; il permet en outre de diagnostiquer la maladie en phase précoce, limitant le risque de complications de la leptospirose par la prescription d'un traitement antibiotique. L'épidémiologie de la maladie a pu être également décrite en termes de sévérité, de caractéristiques démographiques et de saisonnalité. Les résultats confirment la pertinence de la mise en place d'un système de surveillance épidémiologique à visée d'alerte, étroitement articulé avec une stratégie de prévention et de contrôle de la maladie.

BACKGROUND:Leptospirosis is a neglected zoonosis affecting mainly tropical and subtropical regions worldwide, particularly South America and the Caribbean. As in many other countries, under-reporting of cases was suspected in the French West Indies because of inadequate access to diagnostic tests for the general population. METHODOLOGY/PRINCIPAL FINDINGS:In order to estimate the real incidence of leptospirosis in Guadeloupe and Martinique, a study was performed in 2011 using the three prevailing available biological tests for diagnosis: Microscopic Agglutination Test (MAT), IgM ELISA and PCR. The study investigated inpatients and outpatients and used active case ascertainment from data provided by a general practitioners' sentinel network. The epidemiology of the disease was also described in terms of severity and demographic characteristics. Leptospirosis incidence was estimated at 69.4 (95%CI 47.6-91.1) and 60.6 (95%CI 36.3-85.0) annual cases per 100,000 inhabitants in Guadeloupe and Martinique, respectively, which was 3 and 4 times higher than previous estimations. CONCLUSION/SIGNIFICANCE:Inclusion of PCR and IgM ELISA tests for diagnosis of leptospirosis resulted in improved sensitivity in comparison with MAT alone. Our results highlighted the substantial health burden of the disease in these two territories and the importance of access to appropriate laboratory tests. Based on our results, PCR and IgM ELISA tests have now been included in the list of tests reimbursed by the national system of social security insurance in France. Our results also underline the relevance of implementing an integrated strategy for the surveillance, prevention and control of leptospirosis in the French West Indies.