[Monitoring of activity of influenza in Santa Fe, Argentina, 2005-2010]

Abstract

BACKGROUND: Influenza viruses have a relevant public health impact. OBJECTIVE: To describe the activity of influenza and assess the morbidity and mortality impact during 2005 to 2010 in Santa Fe, Argentina. METHODS: Epidemiological and virological indicators were calculated based on sentinel surveillance. Mortality data from patients over and under the age of 65 were analyzed using the integrated autoregressive moving average model and an excess of mortality attributable to influenza was determined. RESULTS: The viral circulation effect on morbidity was measured through the evolution in the proportion of influenza-like illness (ILI) patients. Peak incidence was observed between weeks 23 and 33. An excess of deaths was identified in 2007 among patients over 65 and among those under 65 in 2009, which was related with influenza A(H3N2) and A(H1N1)pandemic virus circulation respectively, associated with a higher proportion of virus recovery and a higher ILI percentage. CONCLUSIONS: The sentinel surveillance of influenza is a simple and efficient methodology that identifies influenza trends. Our study showed that the virus has caused a rise of mortality in patients > 65 in epidemic periods associated with the H3N2 subtype and in patients < 65 in the pandemic period with the circulation ofA(HIN1)pandemic virus.