Event-based biosurveillance of respiratory disease in Mexico, 2007–2009: connection to the 2009 influenza A(H1N1) pandemic?

N P Nelson; J S Brownstein; D M Hartley

doi:10.2807/ese.15.30.19626-en

Surveillance and outbreak reports Open Access

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Event-based biosurveillance of respiratory disease in Mexico, 2007–2009: connection to the 2009 influenza A(H1N1) pandemic?

N P Nelson¹, J S Brownstein², D M Hartley³
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Affiliations: ¹ Georgetown University School of Medicine, Department of Paediatrics, Washington, DC, United States ² Children's Hospital Boston and Harvard University Medical School, Boston, MA, United States ³ Georgetown University School of Medicine, Department of Microbiology and Immunology and Department of Radiology, Washington, DC, United States

Correspondence:
N Nelson
nelson isis.georgetown.edu
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Citation style for this article: Nelson N P, Brownstein J S, Hartley D M. Event-based biosurveillance of respiratory disease in Mexico, 2007–2009: connection to the 2009 influenza A(H1N1) pandemic?. Euro Surveill. 2010;15(30):pii=19626. https://doi.org/10.2807/ese.15.30.19626-en Received: 07 Dec 2009

Abstract

The emergence of the 2009 pandemic influenza A(H1N1) virus in North America and its subsequent global spread highlights the public health need for early warning of infectious disease outbreaks. Event-based biosurveillance, based on local- and regional-level Internet media reports, is one approach to early warning as well as to situational awareness. This study analyses media reports in Mexico collected by the Argus biosurveillance system between 1 October 2007 and 31 May 2009. Results from Mexico are compared with the United States and Canadian media reports obtained from the HealthMap system. A significant increase in reporting frequency of respiratory disease in Mexico during the 2008-9 influenza season relative to that of 2007-8 was observed (p<0.0001). The timing of events, based on media reports, suggests that respiratory disease was prevalent in parts of Mexico, and was reported as unusual, much earlier than the microbiological identification of the pandemic virus. Such observations suggest that abnormal respiratory disease frequency and severity was occurring in Mexico throughout the winter of 2008-2009, though its connection to the emergence of the 2009 pandemic influenza A(H1N1) virus remains unclear. .