ABSTRACT
Environmental Effects on Lyme Disease Incidence in the State of
Virginia [3]
Author:Tam Tran, MAVirginia Commonwealth University, School of Medicine
Background: Lyme disease is the most common nationally reported vector-borne
disease and has increased in incidence and geographic range. Physical conditions
influence the biological conditions, affecting Lyme disease transmission dynamics.
Previous studies have demonstrated that the incidence of Lyme disease correlates to
landscape ecology and climate in the Northeast but such studies are limited in the
Southeast. We determined the strength of association between climatic factors and the
geographical incidence of Lyme disease in Virginia.
Methods: Monthly station and/or satellite climate data (temperature, precipitation, soil
moisture) in the International Research Institute (IRI) Data Library was obtained from
1999-2013. Time series were created for the six climate division in Virginia. Climate
data was gridded over each county and independent city. Time lags were performed to
determine the effects of climatic variables on the nymph and larval stages. Pearson
correlation was used to study the significance of the disease and climate relationships,
which were spatially mapped in ArcGIS.
Results: When examining the relationship between temperature anomalies during the
larval stage and Lyme disease incidence, four of the climate divisions had significant
Pearson correlation values (p <.01): Eastern Piedmont (.631), Northern (.624), Central
Mountain (.566), and Southwest Mountain (.576). When studying temperature
anomalies during the nymph stage and Lyme disease incidence, Eastern Piedmont
(.406), Western Piedmont (.399) had p< .1, and Northern (.543) and Central Mountain
(.582) had p<.01. The relationship between precipitation and soil moisture was nonconclusive for VA.
Conclusions: There is a strong association between temperature and Lyme disease
incidence in VA, suggesting warmer temperatures are linked to higher incidence of
Lyme disease. This has not been established in other regions of the US.
Public Health Implications: With a predicted regional increase of 4-8 °C by 2100, this
study has broader implications for managing disease outbreaks in a changing future
climate.
Data Source Utilized: NOAA-NCEP CPC.VDH.US Census Bureau