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New Formula Could Help Stop West Nile Epidemics Before They Start


UT Southwestern has developed a formula that it says could revolutionize the way communities fight West Nile.

And even though recent rains have drenched North Texas, researchers don’t expect a sudden dramatic spike in West Nile cases.

UT Southwestern’s mosquito vector index rating system basically multiplies the mosquito population with the percentage of West Nile infected mosquitoes.

When that number reaches .5 or higher, mosquito control programs should be full steam ahead. Dr. Robert Hayes with UT Southwestern hopes the vector index will help scientists stop epidemics before they start.

“The number of cases of the disease is about three or four weeks behind the actual progress of the infection. And this vector index then allows you to intervene at the very beginning way before you see a lot of sick people," says Hayes, chief of epidemiology and professor of internal medicine at UT Southwestern.

Just to give you some perspective, the Dallas county vector index number is hovering near zero right now. Last summer in the northern part of Dallas county, it got as high as 2.5.

With days of steady rain recently behind us, does the West Nile risk for North Texas suddenly get higher? Dr. Haley doesn’t think so.

“I understand from the health department experts that we have more mosquitoes this year than any time. But, there are just no viruses around, and probably the birds are mostly immune and we’re just not seeing any or many infected mosquitoes," says Haley.

While this summer has been a quiet one for West Nile so far, officials with Dallas County Health and Human Services don’t want people to let their guard down.

They’re still asking residents to discourage mosquito breeding by dumping standing water and ask people to wear repellant when outside at dawn or dusk.