[Laboratory based human leptospirosis surveillance in New Caledonia (2001-2005)]

The Pasteur Institute in New Caledonia performs for this territory the biological diagnosis of human leptospirosis; therefore its activity locally gives a rather exhaustive description of this pathology. The results presented here cover the 2001-2005 period and describe the principal epidemiological and biological features of human leptospirosis in New Caledonia. The investigated patients were recruited by the main medical structures: territorial and provincial hospitals, public dispensaries, clinics and general practitioners. The laboratory used the microagglutination test for serological investigations and PCR methods for the early detection of Leptospira genome in clinical samples. 239 cases of leptospirosis were biologically confirmed among 6690 tested patients, giving an average incidence of 21 cases per 100000/year, and a lethality rate of 5.4%. The sex-ratio was 1.8 male/female, patients were predominantly belonging to the 20-50 year age group and were inhabitants from the Northern Province. The circulating serogroups were mainly Icterohaemorrhagiae (69%), Australis (8%) and Pyrogenes (6%). The annual incidence peak occurred in April at the end of the warm season, and the importance of annual outbreaks could be linked with El Ninõ, the main regional climatic phenomenon.