Introduction: On January 18, 2011, a pediatrician at the Gabriel Martin Hospital Center (CHGM) reported to the Indian Ocean Health Agency (ARS-OI) an unusually high number of hospitalizations for viral meningitis during the period from November 15, 2011, to January 15, 2012. The report was forwarded to the InVS Unit for the Indian Ocean Region (Cire OI) for validation and to initiate an epidemiological investigation if necessary. Materials and methods: To validate the signal, Cire OI relied on data from the OSCOUR® network, which collects activity data from the emergency departments of the four hospitals in Réunion. A "viral meningitis" syndrome cluster was constructed, and a spatio-temporal analysis was performed. Concurrently, microbiological and epidemiological investigations were conducted. Results: The spatio-temporal analysis detected an abnormal increase in visits for viral meningitis at the CHGM emergency department and identified a cluster of cases across three municipalities in the west. During the investigations, no epidemiological link could be established between the patients. Laboratory data revealed an increase in the number of requests for viral testing, 5.7% of which were positive for enteroviruses. Discussion and conclusion: Due to their responsiveness and effectiveness, the data from the OSCOUR® network demonstrated the relevance of such a network for verifying and validating reports of a public health event. (R.A.)