NVCC GIS 205
Spring 2009
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About 20,000 reported cases in the USA every
year
Causes symptoms ranging from rash and
fatigue to chronic neurologic problems and
arthritis
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Primarily
transmitted in the
East by the blacklegged or deer tick
(I. scapularis)
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Nymphs (the most
common stage to
transmit Lyme disease)
are about the size of a
poppy seed, inflict a
painless bite, and
transmit the illness
during a 3-5 day long
feeding.
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Age- children ages 5-19 and adults between 45
and 54 years old are at higher risk of
contracting Lyme disease
Gender- males are more likely to contract Lyme
disease than females across all age groups and
account for approximately 53-57% of cases
overall
Exposure- ticks do not travel far on their own,
relying on hosts to pass by close enough for
them to latch on from their questing site
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White-tailed deer- a key host for adult blacklegged ticks and several studies suggest a
direct correlation between the number of deer
and the number of ticks in an area
White-footed mice- important host for blacklegged ticks in the larval and nymph stages,
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White-footed mice are host competent and act as
disease concentrators
Temperature- black-legged ticks are only active
when the temperature is above 35 deg.
Fahrenheit
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Population maps- projected TIGER/LINE data,
then calculated the density of individuals 45-54
per area
Converted to raster and reclassed based on
standard deviations
Repeated the process for children and male
densities
Each layer was weighted according to the
proportion of cases that group represents
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Land cover data was classified by suitablity as
habitat for deer and for mice
Suitability grids were weighted according to
relative contribution to densities of infected ticks
Monthly high and low temperature grids were
combined to form monthly maps of low, medium,
and high tick activity potential
Used ___ to form a map of risk of presence of and
exposure to infected ticks
Used Map Algebra to amplify this by the temporal
risk from higher tick activity
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While my results fit with the research I saw
from Maryland, there is very little research on
the extent or population of I. scapularis or
Lyme disease in Virginia. Likewise, the lack of
information about the location of contraction
(as opposed to diagnosis) of Lyme limited my
ability to analyze the extent to which these
predictive factors actually affect Lyme risk.