Pandemic influenza 2009 on Réunion Island: A mild wave linked to a low reproduction number.

We studied the epidemic trend following the introduction of the pandemic A(H1N1) 2009 in the subtropical Réunion Island. There, the pandemic wave started from week 30 and lasted until week 38, with an estimated attack rate of 12.85 % for symptomatic infections. The best estimate for the initial reproduction number was Ri = 1.26 [1.08; 1.49]. It results that the herd immunity necessary to stop the epidemic growth is of the same magnitude than the attack rate. Thus, a second wave before the 2010 austral winter seems unlikely, unless a viral mutation.

[Electronic transmission of epidemiologic data and monitoring of the chikungunya virus epidemic in Reunion Island, 2006]. / Transmission télématique de données épidémiologiques et surveillance de l'épidémie de chikungunya à la Réunion en 2006.

INTRODUCTION: When the first cases of the 2005-2006 chikungunya epidemic struck Reunion Island, local health authorities set up an island-wide operational epidemiologic surveillance system for these infections. This system relied on vector control teams, which conducted active case-finding around the reported cases, and on a sentinel physician network. In addition, in March 2006, the Sephira and Reunion-Telecom companies, in partnership with the Reunion-Mayotte interregional epidemiology bureau (CIRE), developed an innovative system of epidemiologic monitoring by electronic data transmission. METHODS: This system relied on the participation of volunteer physicians who transmitted epidemiologic data through the data terminals used for the transmission of electronic treatment forms to the health insurance funds. Using the patient's insurance identification card, each physician provided information about consultations related to chikungunya. This information was transmitted, via the Sephira server in France to Reunion-Telecom, which processed, aggregated and transmitted these data weekly to the CIRE. This network was separate from and independent of the sentinel physician network, RESULTS: In all, 44 physicians, accounting for 6% of the general practitioners in Reunion, participated in this system, which went into operation during week 14 of 2006. The data collected allowed an assessment of the trends in the epidemic incidence rate by calculating the percentage of consultations related to chikungunya among all consultations (office visits and house calls). For weeks 14-26 of 2006, when the epidemic transmission had spread across the entire island, the Reunion-Telecom health network data proved to be closely correlated with the results of the sentinel physician network surveillance system used to monitor the epidemic trends (correlation coefficient=0.97). CONCLUSION: The system provided very encouraging results in monitoring disease time trends in a period of massive epidemic. Its simplicity of use and the speed of data transmission are undeniable assets for its future development. Because it offers the possibility of monitoring other diseases with epidemic potential, such as dengue and influenza, it opens new prospects for infectious disease surveillance.