Dengue 1 epidemic in French Polynesia, 1988-1989: surveillance and clinical, epidemiological, virological and serological findings in 1752 documented clinical cases.

An epidemic of dengue 1 occurred in French Polynesia in December 1988 and June 1989. This paper records (i) the trend of the outbreak and its surveillance and (ii) the clinical, epidemiological and virological data obtained from 1752 documented cases. The epidemic reached its peak in February in Tahiti Island, 7 weeks after its recognition. Among 6034 suspect cases reported by sentinel physicians, 60.3% were < 20 years old. The illness was classical dengue. No fatality or case of dengue haemorrhagic fever/dengue with shock syndrome was reported. Of 4792 patients subjected to laboratory testing, 41% were confirmed as positive. The serological attack rate was c. 40%. The estimated number of dengue infections in the Windward Islands was about 20,000. Transmission was associated with Aedes aegypti. Study of documented cases showed a higher confirmation rate in both the civilian population < 15 years old (46.5%) and the susceptible French military population (47.6%) than in older civilians (31.1%, P < 0.05). Furthermore, primary dengue infections were predominant in both of the first 2 groups. The diagnosis was mostly confirmed (i) by virus isolation on day < 5 of illness and (ii) by detection of immunoglobulin (Ig) M on day > or = 5 of illness. The study showed that adequate surveillance of an epidemic requires both clinically and laboratory-based systems.