Influenza outbreak--Madagascar,July-August 2002

In mid-July 2002, Madagascar health authorities were notified of a substantial number of deaths attributed to acute respiratory illness (ARI) in the village of Sahafata (population: 2,160), located in the rural highlands of Fianarantsoa Province, southeastern Madagascar (Figure 1). This region is approximately 450 km (280 miles) south of the capital Antananarivo. The Madagascar Ministry of Health (MOH) and the Institut Pasteur, Madagascar (IPM) initiated an investigation, which found an attack rate of 70% for ARI, with 27 deaths in Sahafata. Pharyngeal swab specimens were collected from ill persons for viral culture. Of the four influenza A viruses that were isolated at IPM, two were identified as type A (H3N2) viruses. In late July, health authorities investigated a similar outbreak in Ikongo District, Fianarantsoa Province. In August, MOH requested assistance from the World Health Organization (WHO) and CDC in investigating the outbreak. In response, an international team of experts from CDC; Institut de Veille Sanitaire, France; Institut Pasteur, France; and WHO was mobilized from the Global Outbreak Alert and Response Network; the team arrived in Madagascar on August 14. This report summarizes the preliminary epidemiologic and virologic findings, which suggest that the outbreak was attributable to influenza A (H3N2) viruses. Further surveillance and research about the epidemiology of influenza in Madagascar is planned.