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APHA Scientific Session and Event Listing

Recorded presentation

Eric Lofgren¹, Nina Fefferman, Ph D², Jack Gorski, Pd D³, and Elena Naumova, PhD². (1) Department of Biology, Tufts University, 163 Packard Ave., Medford, MA 02155, 303-912-2595, Eric.Lofgren@tufts.edu, (2) Department of Public Health and Family Medicine, Tufts University, 136 Harrison Ave, Boston, MA 02111, (3) Blood Research Institute, BloodCenter of Wisconsin, P.O. Box 2178, Milwaukee, WI 53201

Influenza seasonality is one of the best characterized, and least understood, aspects of the dynamics of non-pandemic influenza infection. One factor frequently cited, but rarely rigorously examined in existing literature is the association of seasonal infection rates with ambient temperature and temperature-related factors.

An extensive data set of 2619 laboratory confirmed cases of influenza in Milwaukee, Wisconsin, adjusted for population, was analyzed against an array of climatological variables obtained from NOAA for the period between January 1967 and June 2005. Using regression modeling adapted for time series studies and contour mapping techniques, the relationship between influenza incidence and temperature related indicators was elucidated.

Influenza A infection was found to be strongly associated with a decrease in monthly temperature (r=0.418, p <.0001). More refined examination of these relationships revealed that incidence was greatest in the month subsequent to the coldest month of the year (18.1 ± 3.7 cases/million persons/month), and during relatively warm winters. The typical two-year cycle of seasonality was not observed in this data, and Influenza B had a two month delay in occurrence when compared to Influenza A.

These preliminary results suggest a far more complex relationship between virus, host and environment than had been previously been considered in the context of seasonality. We are supplementing the analysis with influenza mortality and hospitalization data to further explore the full nature of Influenza seasonality, on an epidemiological, mathematical, and virological level.

Learning Objectives: Following this session, the participants will be able to

• Identify seasonal trends in non-pandemic influenza.
• Describe the impact of a wide range of factors on influenza seasonality.
• Recognize the need for multidisciplinary collaboration to further understand the topic.
• Apply the concept of the seasonal incidence of infectious disease in surveillance, prevention and research.

Keywords: Infectious Diseases, Biostatistics

Presenting author's disclosure statement:

Any relevant financial relationships? No

Recorded presentation