Mosquito populations are flourishing in Union County this year, and the chances of humans being infected with West Nile virus are up accordingly.
Vector Control Program Director Kelly Beehler said Wednesday the sudden onset of hot weather this spring created conditions favorable to large hatchings of mosquitoes, which spread the virus to humans.
"The heat we've gotten over the last few weeks combined with the snow melt has caused some of the worst conditions I've seen," Beehler said Thursday.
West Nile is a virus that mainly infects birds, but also infects humans, horses, dogs and other animals. In humans the main route of infection is the bite of an infected mosquito.
Beehler said he is concerned that a mosquito trapped recently in Tri-Cities, Wash., tested positive for the West Nile virus.
Tri-Cities vector control specialists detected the presence of the virus in the first test of the year. Beehler said that is highly unusual.
"Typically the middle of July is when you see it," he said.
In birds, West Nile affects corvids like crows and magpies, raptors including hawks and eagles, and also robins. When dead or apparently sick birds start turning up in numbers, it's a tip-off that West Nile is present.
Recently, a dead magpie in Island City was sent off for testing for the virus. Beehler said it is the first test of the year for Union County. Results are not back yet.
Two years ago in Union County, the county board of commissioners declared a state of emergency because of widespread presence of West Nile-infected mosquitoes.
The vector control program mounted an intensive mosquito control effort, employing both aerial and ground spraying techniques.
"We had seven or eight cases of human West Nile that year, and we might have had 40 or 50 if we hadn't taken strong action," Beehler said.
The local vector control program, funded by a tax levy, offers mosquito control county-wide. With mosquito populations flourishing anew this spring, Beehler said the program is receiving a high number of requests for spraying. Some 125 requests came in last week, he said.
He said recent rains have made it difficult to keep the program on schedule.
"We're going as fast as we can, but every time there's a storm it sets us back," he said.
Weather permitting, aerial spraying is planned Tuesday or Wednesday in rural areas along Catherine Creek and the Grande Ronde River, including lands between Hot Lake and Union, and between Greys Corner and Imbler.
Beehler said there are currently no plans for aerial spraying over population centers.
According to the U.S. Center for Disease Control, one in 150 people infected with West Nile virus will develop severe illness.
The severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.
These symptoms may last several weeks, and neurological effects may be permanent.
To reduce the threat of West Nile virus, people should use mosquito repellent, eliminate standing water where mosquitoes can lay eggs, and install and repair window and door screens. To see more of The Observer or to subscribe to the newspaper, go to http://www.lagrandeobserver.com/. Copyright (c) 2009, The Observer, La Grande, Ore. Distributed by McClatchy-Tribune Information Services. For reprints, email tmsreprints@permissionsgroup.com, call 800-374-7985 or 847-635-6550, send a fax to 847-635-6968, or write to The Permissions Group Inc., 1247 Milwaukee Ave., Suite 303, Glenview, IL 60025, USA.
Copyright (C) 2009, The Observer, La Grande, Ore.