Jun 4, 2007 11:02 pm US/Mountain
Experts Say It Could Be A Bad Mosquito Year
Good Question: How Bad Will The Mosquitoes Be This Summer?
by Alan Gionet
DENVER (CBS4) ―
"When they come out it's irritating; defiantly irritating," said a man playing with his children at a fountain in Stapleton. "My son got bit his whole side had mosquito bites in his whole side," said a woman. We've had good rain this spring. It's been a terrific help in keeping the fire danger down, but more rain means more standing water, and that means more mosquitoes.
"It has potential to be a very bad year," said Tony Stilwell of Colorado Mosquito Control, a business that contracts with cities and counties throughout Colorado.
In one area of Lochbuie, where a test will typically uncover 100 mosquitoes, Stilwell said they recently found 1,000. The high water has released mosquito eggs laid in the mud several years ago. Some mosquitoes lay the eggs in drying mud. Water that hasn't been this high in a while is soaking them enough to get the larvae started.
Stilwell said samples are also showing a great number of the type of mosquitoes that can carry the West Nile virus. "More and more the sites, we're bringing back larval samples from were culex tarsalas mosquitoes."
The culex tarsalas and culex pipiens can both carry West Nile from birds to humans. Colorado had 2,947 confirmed cases in 2003. While the culex mosquitoes are being found, it doesn't necessarily translate into more West Nile. 2003 was a dry year.
"It depends on the temperatures," Stilwell said.
Experts are still formulating theories on West Nile because it arrived in the U.S. only eight years ago. A recent theory suggested dry, hot weather causes birds that carry the virus to congregate around the few remaining water sources. That's also where mosquitoes are concentrated in a dry year. Once the culex mosquitoes bite the birds and get the virus, they can then transmit it to humans with another bite. But West Nile has killed many of the infected birds. With as much water as there is this year, experts believe the birds could be spread out.
"I don't think it's going to be as bad as 2003. Kind of the rule of thumb is that once West Nile comes through it's not going to get that bad again," said Stilwell. But with little data, scientists aren't sure. One thing they know is that warm temperatures above 85 to 90 degrees caused the mosquitoes to reproduce faster and the virus to replicate more often. So this year's mosquito season, and maybe the West Nile season, will depend on the weather ahead.
"Really when we look at the next three weeks, that is when it's going to come down to the wire and let us know the kind of year we're really going to have," Stilwell said.
We've only scratched the surface on this year's mosquito report.
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