| West Nile Virus (WNV) has recently appeared in the Unites States in the New York City area in 1999. In 2002, a significant outbreak occurred in Ohio. Cuyahoga County recorded nearly half the deaths in the state. Consequently, important public health resources have been focused on the surveillance, study, and prevention of this vector-borne disease. Like many states, Ohio has suitable vector species, such as those in the genus Culex, capable of transmitting the infection and maintaining the mosquito-bird life cycle of West Nile Virus. Surveillance relative to arboviruses in mosquitoes involves dipping for larva and trapping adults to determine the frequency of WNV infection in order to target control measures to prevent disease. These activities are expensive and labor intensive.;This study demonstrates the utility of geographic information system (GIS) analysis as an adjunct in disease surveillance activities. It examines environmental factors using an 'ecological niche' model. Various risk maps were generated and map analyses conducted to establish endemic levels, direction of spread, risk areas, possible relationships with environmental factors, and implications for human disease in Cuyahoga County, Ohio. Over a five year period (2003-2007), environmental variables in half mile trap buffer areas were compared to MIR positivity using logistic regression analysis. Soil type, slope, land use, catch basins, wetlands, and one and two month average precipitation and one month average temperature were not found to be significant contributors to WNV positivity at this scale. Two month average temperature was significant (p<0.0001). Old type catch basins that hold water seems to be associated with MIR positivity when mapped, and this may explain the lack of significance in the natural environmental factors studied. Catch basin type was not significant however in this study (p<0.182) in logistic regression models that used the first NCLD land use categorization; although continuing work is demonstrating the significance of catch basin type when land use is appropriately categorized. Differences between mosquito breeding in urban/suburban communities with extensive catch basin systems and in rural areas are discussed in reference to the findings of this study... |
