MSU studying environmental causes of deadly West Nile virus

Contact: Phil Hearn

A Mississippi State researcher is taking a close look at environmental factors that might promote the spread of West Nile virus, a potentially life-threatening disease transmitted to humans by mosquitoes.

Bill Cooke, an assistant professor of geosciences, is utilizing a $15,000 grant from the National Institutes of Health to assess the dangers West Nile poses for individuals--particularly sportsmen, natural resources managers, recreation employees and others whose outdoor activities make them more vulnerable to mosquito attacks.

"West Nile virus can be fatal (to humans), depending on the seriousness of the infection," said Cooke, also an extension specialist with MSU's GeoResources Institute. "The elderly and people with immune system deficiencies are more at risk."

With expertise in remote sensing and GIS-Geographic Information Systems-Cooke is using automated computer software to model geographic and climatic conditions associated with the spread of vectored diseases, those passed from one host to another. Mosquitoes get West Nile from birds and pass it on to humans.

"We need to be looking at environmental causes in Mississippi," said Cooke, a Jackson native and 1970 graduate of the city's Wingfield High School.

The MSU project--supported by the geosciences department, GRI and MSU Extension Service--is part of a broader NIH research program administered by East Carolina University's Southern Coastal Agromedicine Center. Second-year funding is being sought, Cooke said.

"This is applied research that will benefit all Mississippians," said Mark Binkley, geosciences department head. "Our goal three years ago, when we created our new GIS program, was to be able to attract highly qualified members like Bill, who can use this cutting-edge technology to attack modern-day problems."

Cooke said a range of variables impact the spread of mosquito and tick-borne diseases. He also is assisting MSU's colleges of veterinary medicine and wildlife and fisheries in a separate, NASA-funded study of risks posed by ticks, which transmit Lyme Disease and Heartwater Fever. Lora Ballweber of the veterinary college leads that effort.

"We'll model bird habitats, climatic influences, vegetation, water sources and conditions that favor development of mosquito larvae," Cooke said of the West Nile project.

"There is a limited view of all the factors associated with complex biological systems and there's some thought that we may not have been going deep enough into those issues-that the quality of the data has not always been the best," he added. "GIS helps deal with the problem of evaluating and connecting all of the data."

The Mississippi State Department of Health reported its first 2004 case of the West Nile virus in April, an infected bird in Marion County, signaling the start of the season for mosquito-borne illnesses. Precautions, information and statistics are updated regularly on the West Nile virus at the department's Web site at www.msdh.state.ms.us.

In 2003, 83 people were infected in Mississippi and two died. An outbreak in 2002, however, was far worse for the state and nation. That year, 193 human cases were reported in Mississippi, resulting in a dozen fatalities in Coahoma, Grenada, Hinds, Jones, Lee, Madison, Pike, Simpson, Washington and Yazoo counties.

According to the Atlanta-based Centers for Disease Control and Prevention, West Nile infections grew from an initial U.S. outbreak of 62 cases in 1999 to 4,156 reported cases in 2002, including 282 deaths. Thirty-nine states and the District of Columbia reported human cases that year.

"Mississippi and Louisiana were the epicenter of the 2002 outbreak," said Cooke, who holds three forestry degrees from MSU, including a 1997 doctorate.

According to the professor, rainy seasons followed by dry weather, which allows pools of water to form and attract mosquitoes, may be more conducive to the spread of West Nile than continuous rain, which seems to have a flushing or diluting effect. It's just one of many environmental or climatic conditions researchers must consider.

Birds are very susceptible to West Nile, especially blue jays and crows, and dead birds in an area can be an early warning that infected mosquitoes are present. Individuals can take precautions against exposure to mosquito bites by using insect repellants containing DEET; wearing light, long-sleeved clothing; emptying standing water and installing screens; and reporting dead birds to local health authorities.

Although only about two of every 10 people bitten by an infected mosquito will experience any illness, the flu-like symptoms of those who do can be very hard to detect. According to the CDC, onset of the virus may be insidious or sudden with fever, headache, malaise and occasionally prostration. Infection may lead, however, to encephalitis, with a fatal outcome or permanent neurological damage.

"Some people may have West Nile virus and not even know it," said Cooke, who has a close friend who contracted the infection two years ago and still is recuperating.