A population-based study on incidence and economic burden of influenza-like illness in south China, 2007

Objectives: The disease burden of influenza-like illness (ILI) in most tropical and subtropical countries has not been described adequately to date. The aim of this study was to determine the epidemiology and incidence of ILI, and to assess the economic burden in south China. Study design: Prospective study. Methods: A population-based household survey was conducted quarterly in 2007 in Guangdong Province. Results: The average number of subjects in each quarterly survey was 13,687. In total, 1002 cases of self-reported ILI were identified in all four surveys, indicating an annual incidence of 7.23 cases of ILI per 100 persons. The second quarter had the highest incidence of ILI (2.83 cases per 100 persons). Children aged 1-4 years, <1 year and 5-9 years had the highest annual incidence rates of ILI (49.87, 35.19 and 21.24 cases per 100 persons, respectively). The incidence of ILI was significantly higher in males than females (P < 0.001), and significantly higher in rural residents than urban residents (P < 0.001). The individual cost per episode of ILI represented approximately 20% of monthly per-capita income of residents. Conclusions: The results of this large-scale household study confirm that ILI places a substantial health and economic burden on south China. Ultimately, the results of this study will provide further information for understanding the disease burden of influenza in subtropical areas. (C) 2011 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.