SPECIFIC EPIDEMIOLOGIC SURVEY OF DENGUE-FEVER - METHODOLOGY AND ITS SIGNIFICANCE DURING THE 1996 DENGUE TYPE-2 EPIDEMIC IN FRENCH-POLYNESIA

Dengue fever is present in tropical and subtropical regions and its ge ographical extension and the simultaneous increase of its mortality ar e worrisome. In endemic or epidemic countries, the aim of dengue-speci fic epidemiological surveillance is to confirm as soon as possible the circulation of a nsw viral dengue serotype, i.e. the beginning of an epidemic. The efficiency of the control strategy is improved by an ear lier epidemic alert. In French Polynesia, dengue-3 virus circulated si nce 1989 at low level and, in May 1996, a specific epidemiological sur veillance was undertaken because of the threat of a dengue-4 epidemic. From each suspected dengue case reported by 18 Polynesian physicians located in the Societe Islands, a blood sample was taken for virologic al assay and clinical data were reported. Between May and November 199 6, the virology unit of the Institut Malarde isolated 21 viruses (2 de ngue-3 and 19 dengue-2) from 302 suspected cases. The dengue-specific epidemiological surveillance confirmed that dengue-2 virus was circula ting and reduced the time of the epidemiological alert by 2 or 3 month s compared to previous epidemics. Taking inter account the day of illn ess, a logistic regression undertaken on the clinical data showed that the absence of cough was the only predictive sign of dengue diagnosis . The performance of this dengue-specific epidemiological surveillance system led us to consider its implementation in all concerned countri es. A collaboration with international reference laboratories could be a solution fur the developing countries.