For example, the 1991 outbreak originated in the Alabama-Louisiana region and then spread north. By contrast, the 1997 the epidemic started in central Tennessee. The 1999 epidemic started in western Minnesota while the 2003 epidemic spread from the gulf region of Texas and Louisiana, according to Naumova. Three of the epidemics peaked in the first week of January while a fourth peaked in the last week of December. Nationally, the average peak occurred during the third week of January.
Naumova points out that the four seasons reveal the diversity exhibited by seasonal outbreaks. "In these years we see that the outbreaks points of origin shifted, as did its geographic spread," she says.
Naumova's ongoing research involves developing mathematical models for analysis of large databases to study infectious diseases and exposure assessment. In an earlier study, researchers analyzed a larger data set from 1991 to 2004. They found that over the 13 seasons, seasonal flus generally peaked earliest in the west and spread east.
While mapping reveals variations in peak timing, intensity, and geography, the factors that influence these parameters are unknown and require further investigation. In the larger picture, Naumova says dynamic mapping could potentially help fill a gap in influenza research.
"It would help give us insight into what kinds of questions to ask. This can lead to a framework from which we are able to develop new research questions," says Naumova, who adds that mapping is only one part of the puzzle. "We also must establish methodologies that use science-based definitions, reliable data and standard methods for presenting data and assessing statistics."
|Contact: Alex Reid|