[Outbreak of influenza pandemic virus A(H1N1) 2009 infections in the Emergency Department, Saint-Pierre, Réunion Island, July-September 2009].

A new H1N1 virus originating from swine recently emerged as the first influenza pandemic of the 21st century. On July 3, 2009, this new influenza A(H1N1) virus (S-OIV) of swine origins was identified in Réunion Island, a French overseas department located in the southern hemisphere. The present study describes the characteristics of the epidemic from July 3 to September 30, 2009. Among the 479 patients included in our study (236 males, 37.3 ± 19.0 years), 255 (53.2%) were reported to have comorbidities or risk factors (RF) for complications. Complications occurred in 160 patients (33.4%). The most common complications were bronchial hyperreactivity (52.7%), pneumonia (32.1%), and decompensation caused by comorbidity (17.9%). 111 patients (23.2%) required hospitalization. Patients aged 65 and over, accounted for 11.9% of all patients, 32.4% of hospitalized patients and 22.5% of complicated S-OIV infections. Regardless of age, comorbidity and/or RF were reported in 80.0% of complicated S-OIV infections and 91.0% of hospitalized patients. Recommendations for surveillance, prevention and policy for persons with RF, particularly respiratory disease, are justified. However, the absence of risk factors did not prevent the occurrence of complications, present in 14.3% of the cases.