On reunion Island, in response to the threat of emergence of the pandemic influenza A(H1N1)2009 virus, we implemented an enhanced influenza surveillance from May 2009 onwards in order to detect the introduction of the pandemic H1N1 influenza and to monitor its spread and impact on public health. The first 2009 pandemic influenza A(H1N1) virus was identified on July 5, 2009 on a traveller returning from Australia, while the seasonal influenza B virus activity had already been detected. By the end of July, a sustained community pandemic virus transmission has been established. Pandemic H1N1 influenza activity peaked during week 35 (24 to 30 August), 4 weeks after the beginning of the epidemic. The epidemic ended on week 38 and lasted 9 weeks. During these 9 weeks, an estimation of 66,915 persons who consulted a physician could have been infected by the influenza A(H1N1)2009 virus giving a cumulative attack rate of 8.26%. Taking into account the people who didn't consult, the total number of infected persons reached 104,067 giving a cumulative attack rate of 12.85%. The crude fatality rate for influenza A(H1N1)2009 and the CFR for acute respiratory infection was of 0.7 / 10,000 cases. Our data show that influenza pandemic did not have a health impact on global mortality on Reunion Island. These findings demonstrate the value of using an integrated epidemiologic, virologic and hospital surveillance in order to monitor the scope of an epidemic, to identify circulating strains and to provide some guidance to public health control measures.
Auteur : D'Ortenzio E, Renault P, Jaffar Bandjee MC, Gauzere BA, Lagrange Xelot M, Fouillet A, Poubeau P, Winer A, Bourde A, Staikowsky F, Morbidelli P, Rachou E, Thouillot F, Michault A, Filleul L
Clinical microbiology and infection, 2010, vol. 16, n°. 4, p. 309-16