Wednesday, 17 November 2004 - 10:24 AM
1005

Spatial analysis of Aedes vexans at two locations with high incidence of West Nile virus

Russell Barbour, russell.barbour@yale.edu1, Charles Palmisano, chuck_palmisano@yahoo.com2, Michael Doyle, mdoyle@comosquitocontrol.com3, and Durland Fish, durland.fish@yale.edu1. (1) Yale University, Dept. of Epidemiology and Public Health, 60 College Street, New Haven, CT, (2) St. Tammany Parish Mosquito Abatement District, P.O. Box 696, Slidell, LA, (3) Colorado Mosquito Control, Inc, 695 N. 7th Ave, Brighton, CO

Aedes vexans transmission of West Nile Virus(WNV) to humans is not well studied. Persistent positive pools and aggressive human biting habit suggest a possible role in human WNV risk. We modeled spatial density of Ae. vexans in St. Tammany Parish, LA and Ft. Collins, CO for 2002 and 2003 years of high human WNV incidence at the respective sites. Remotely sensed Moderate Resolution (MODIS) Infra-Red Precipitable Water Column data, suggested high humidity promoted migration of female mosquitoes at both sites. Enhanced Vegetation Index data from MODIS correlated with breeding sites, but not adult clusters. 52 NJ Light traps and 19 CDC Light traps provided data for the Louisiana spatial model. Significant clusters of Ae. vexans correlated (p<.01) with populated areas and human WNV cases. Ae. vexans catches correlated with human landing rates ( p< .01). From April - June 2002, preceding the first human WNV cases in St. Tammany, Ae. vexans was the most abundant species observed in human landing observations. Statistically significant landing clusters were not spatially associated with presumed breeding areas. Spatial autocorrelation for Ae. vexans varied from 3155 meters in Colorado to 18000 meters in Louisiana. Applying spatial statistics and Artificial Neural Networks (ANN), dispersal of females from breeding sites to human hosts near Ft. Collins were modeled from 71 light traps. High humidity promoted Ae. vexans clustering more weakly than at the Louisiana site. This analysis suggests a possible role for Ae. vexans as a vector of WNV to humans.


Species 1: Diptera Culicidae Aedes Aedes vexans (Inland Floodwater Mosquito)
Keywords: spatial statistics, artificial neural networks

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