Lyme Disease Emergence in Virginia: An Examination of the Demographic and Environmental Variables Correlated to the Spatial Pattern of Disease Incidence

Since its initial identification in 1975, Lyme disease has become a public health concern in the U.S.  Increased concern is sparked by the rapid rate at which the disease is emerging into new areas.  One area of disease emergence is the state of Virginia which has been experiencing exponentially increasing rates of the disease.  This research studies Virginia's landscape-level habitats to explore demographic and environmental variables related to the spread of Lyme disease.

The land cover data came from the National Land Cover Database (2006), demographic data came from the U.S. census (2010), and Lyme disease case data came from the Virginia Department of Health (2006-2010).  Key variables examined in this statewide study include the percentages of landscape types measured inside each census tract, measures of forest fragmentation, and measures of land cover interspersion inside state census tracts.

Analysis was carried out using a spatial Poisson regression model.  Of the original 15 variables, 10 were significantly correlated to Lyme disease.  The six that were positively correlated with disease incidence include percent herbaceous land, percent water, two edge contrast measurements of herbaceous-forest land, median age, and average income.  The four that were negatively correlated were percent developed, population density, and two edge contrast measurements of developed-herbaceous land.

Overall results indicate that specific environmental and demographic variables are associated with increased disease incidence as Lyme disease emerges in Virginia.  Results from this study could help create a predictive statewide map for Lyme disease incidence and aid in disease awareness and resource allocation.