Released June 25, 2007
STILLWATER, Okla. – Oklahoma’s wet spring has created a huge mosquito population, but it is the drier conditions of mid- to late-summer that increase concerns about mosquito transmission of West Nile virus.
Of 62 different species of mosquitoes found in the state, only three carry the virus, said Lisa Coburn, Oklahoma State University senior agriculturalist.
Coburn has been part of an effort to study the particular mosquitoes that are known to carry West Nile virus since the state’s first cases in 2002.
Oklahoma saw an increase of human cases of West Nile virus in 2006, and a decline in equine cases, according to Oklahoma State Department of Health records.
“We had 48 human cases last year that were reported to the state health department,” said Dr. Kristy Bradley, deputy state epidemiologist and public health veterinarian. Bradley noted there were only two laboratory confirmed equine cases in 2006.
The disease is more likely to affect infants, adults over the age of 50 and those who have a compromised immune system.
Two common Oklahoma mosquitoes that likely transmit West Nile virus are the southern house mosquito and the Asian Tiger mosquito. The Asian Tiger is the only species in the state that prefers to feed in the daytime instead of the dusk-to-morning habit of other mosquito species. They are generally not prevalent in the state until Oklahoma’s temperatures crank up in July.
Bradley said the West Nile virus originated in regions of Africa and is spread primarily when it is dry and temperatures are high.
The virus was costly and devastating to the Oklahoma equine population when it first hit the state. Though vaccination has effectively brought the disease under control, Bradley does not want anyone to get a false sense of security.
“We know that we will have mosquitoes carrying West Nile virus every summer in Oklahoma,” Bradley said.
She said horses should receive annual booster vaccinations, readily available as over-the-counter products.
The public has a number of misconceptions about the disease and about mosquitoes, Coburn said, with education being a key factor in helping to prevent infection with the virus.
Repellents are readily available that work. Other easily applied common sense measures such as limiting standing water can also limit the growth of mosquito populations.
Bradley said Oklahoma’s wet spring has helped to limit mosquito species that carry the virus, but cases of both human and equine West Nile virus were reported in the state in June last year.
--30--
http://www2.dasnr.okstate.edu/Members/donald.stotts-40okstate.edu/west-nile-season-is-here
Contact: Janet F. Reeder, (405) 744-3651, janet.reeder@okstate.edu
