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ACCESSION NO: 0406863 SUBFILE: CRIS 

PROJ NO: 5410-32000-014-15S AGENCY: ARS 5410 

PROJ TYPE: USDA COOPERATIVE AGREEMENT PROJ STATUS: TERMINATED 

START: 06 JUL 2004 TERM: 30 APR 2009

INVESTIGATOR: REEVES W K; MILLER S N

PERFORMING INSTITUTION:

UNIVERSITY OF WYOMING 

207 ARTS AND SCIENCES BUILDING 

LARAMIE, WYOMING 82071

USE OF GEOGRAPHIC INFORMATION SYSTEM (GIS) METHODS TO UNDERSTAND SPATIAL

PATTERNS OF MOSQUITO VECTORS OF WEST NILE VIRUS

OBJECTIVES: The objective of this cooperative research project is to conduct geo-spatial analyses of

climatic and bio-geographic factors that influence the distribution and vector competence of Culex

tarsalis in the inter-mountain West. This mosquito species is a very competent vector of WNV, and

using GIS to analyze and interpret climatic and bio-geographic factors that support mosquito

populations will define spatial patterns where risk for exposure to WNV is high for humans, livestock,

and wildlife populations. The same methods will be applied to assess risk of a potential Rift Valley

fever virus introduction.

APPROACH: The goal is to be able to predict areas and conditions of high and low risk for WNV. This

will focus mosquito control programs and call attention to the need for use of personal protection

methods (insect repellents). Vector-borne diseases are the product of habitats that support vector

populations, ambient temperatures that enhance rates of larval development and virus amplification,

and wildlife species that serve as donors of virus ingested during vector blood feeding. Using GIS, it

will be possible to predict geographic areas and seasonal patterns that are necessary for outbreaks of

arbovirus to occur. GIS methods provide powerful tools for spatial analysis of climatic and

biogeographic factors that promote vector competence among mosquito populations. We will use

satellite imagery and ground-based data to define environmental profiles for habitats and areas that

support populations of C. tarsalis. These data will define most suitable habitats and best conditions for

the species and serve as a basis for predictions of where and when this mosquito is most abundant on

a larger spatial scale. Climatic data superposed on the spatial abundance of C. tarsalis will enable

predictions of maximum risk for WNV transmission, and potentially, Rift Valley fever virus.

PROGRESS: 2004/07 TO 2009/04

Progress Report Objectives (from AD-416) The objective of this cooperative research project is to

conduct geo- spatial analyses of climatic and bio-geographic factors that influence the distribution and

vector competence of Culex tarsalis in the inter- mountain West. This mosquito species is a very

competent vector of WNV, and using GIS to analyze and interpret climatic and bio-geographic factors

that support mosquito populations will define spatial patterns where risk for exposure to WNV is high

for humans, livestock, and wildlife populations. The same methods will be applied to assess risk of a

potential Rift Valley fever virus introduction. Approach (from AD-416) The goal is to be able to predict

areas and conditions of high and low risk for WNV. This will focus mosquito control programs and call

attention to the need for use of personal protection methods (insect repellents). Vector-borne diseases

are the product of habitats that support vector populations, ambient temperatures that enhance rates
11/20/2019 More

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of larval development and virus amplification, and wildlife species that serve as donors of virus

ingested during vector blood feeding. Using GIS, it will be possible to predict geographic areas and

seasonal patterns that are necessary for outbreaks of arbovirus to occur. GIS methods provide

powerful tools for spatial analysis of climatic and biogeographic factors that promote vector

competence among mosquito populations. We will use satellite imagery and ground-based data to

define environmental profiles for habitats and areas that support populations of C. tarsalis. These data

will define most suitable habitats and best conditions for the species and serve as a basis for

predictions of where and when this mosquito is most abundant on a larger spatial scale. Climatic data

superposed on the spatial abundance of C. tarsalis will enable predictions of maximum risk for WNV

transmission, and potentially, Rift Valley fever virus. Significant Activities that Support Special Target

Populations Research in this project centered on the development of habitat and temperature-based

models that can be used for risk assessment in mosquito- borne illness, specifically West Nile and Rift

Valley fever viruses. Geographic Information System (GIS) technologies were developed to create

point-based and spatially explicit models of both mosquito habitat and risk of virus transmission. Case

studies were performed in Wyoming and California for West Nile Virus using a retrospective approach.

Theoretical models for future risk based on global climate change were developed for both West Nile

Virus and Rift Valley fever. The WNV degree day modeling project was field tested in California in

2007-2008, and was modified to include new data on virus replication rates and host susceptibility.

These changes were incorporated into a new model along with modifications to match additional field

conditions and the inclusion of a higher resolution thermal profile. This new model had an excellent

match to field data in CA. Data for additional states are being added to the model to further validate its

use. The computer model has now been published. The degree day model was also used to

determine the most at-risk areas for RVF becoming established in the continental US. It focused on

five states, four of which (Minnesota, California, Texas, and New York) were chosen because of their

identification as high risk for RVF introduction by pathways analysis and the fifth (Nebraska) chosen

for its central location and large livestock industry. Highest levels of risk were found in parts of

California and Texas. Locations where RVF introduction would have the greatest potential impact to

the livestock industry were in California, Texas, and Nebraska. This analysis is currently in

preparation. ADODR monitoring activities to evaluate research progress were through meetings, email

and phone calls.

PUBLICATIONS (not previously reported): 2004/07 TO 2009/04

No publications reported this period.