[Human leptospirosis in French Polynesia. Epidemiological, clinical and bacteriological features]

Leptospirosis is a severe zoonotic disease that constitutes a major public health problem for the island populations of French Polynesia. Due to protean clinical manifestations and the risk of misdiagnosis with dengue fever, endemic viral disease, laboratory studies are necessary to confirm diagnosis of leptospirosis. At the request of the Pacific Public Health Surveillance Network, a prospective study was conducted in the population of Raieatea in the Windward Islands and the Marquis Islands to determine the epidemiological features of the disease and to define appropriate control measures. A total of 113 patients were enrolled in study between March 2004 and March 2005. Thirty-three cases were confirmed based on demonstration of serum DNA or seroconversion. The estimated annual incidence of leptospirosis was 1.7 per 1000 inhabitants. Cases involved mainly (75%) young men (mean age, 30.5 years) and occurred predominantly during the rainy season. Swimming in fresh water was the only factor showing significant correlation (p < 0.02) with positive diagnosis of leptospirosis. The most frequently identified serotype was Leptospira icterohemorrahgiae (43% of strains), thus suggesting that the rat was the most common human transmission vector. However other serotypes were found, underlining the presence of diverse reservoirs and casting doubt on the efficacy of immunization using a monovalent vaccine. These findings also indicate that enhancement of prevention and control measures for leptospirosis is needed.