Multicentre survey of incidence and public health impact of leptospirosis in the Western Pacific.

The objectives of the study were to describe the mode of circulation (endemic or epidemic) of human leptospirosis in various Pacific island states and territories by identifying predominant Leptospira serogroups and the most probable routes of human exposure, and to recommend a feasible laboratory strategy for leptospirosis in the Pacific. From September 2003 to December 2005, 263 leptospirosis suspect patients were recruited by public practitioners on 11 Pacific islands, using the WHO case definition. Diagnosis was confirmed using a three-level serology algorithm and a regional laboratory network. Sixty-nine leptospirosis cases were identified from seven islands: Futuna, Raiatea and the Marquesas Islands where outbreaks were apparent, and Vanuatu, Fiji, Palau and Wallis where sporadic cases indicated at least the presence of the disease. Most patients were men aged 17-40 years. The infection appeared to occur during the course of normal daily activities more often than following specific professional exposure. The dominant presumptive serogroups were Icterohaemorrhagiae and Australis, highly suggestive of a rodent reservoir. This study confirms the widespread presence of leptospirosis in the Pacific region. It should help in the implementation of local leptospirosis control plans and highlights the role of on-site laboratory confirmation.