Jul 192011
Authors: Allison Knaus

While milder temperatures, an above-average amount of rain-fall and mountain runoff have kept numbers of West Nile Virus-carrying mosquitoes to a below average number, aggressive mosquitoes have prospered.

Even though disease-carrying mosquitoes haven’t been found, aggressive, buzzing and biting mosquitoes are definitely out there in large numbers, said Mike Calhoon, the City of Fort Collins project manager for the West Nile Virus mitigation program.

“With elevated river and runoff levels, water is moving very fast, providing new sites for flood-water or nuisance mosquitoes to live in,” he said.

While flood-water mosquitoes are aggressive and annoying, they don’t carry West Nile like the Culex, a gene of mosquito that typically carries the virus, Calhoon added.

However, the common nuisance mosquitoes that don’t carry West Nile breed in the water and can remain unhatched until the water hits them, said Jessica Schurich, the operations manager for the northern Front Range branch of Colorado Mosquito Control.

“We kind of have a trade off and we’ll get stuck with one or the other,” Schurich said. “Culex mosquitoes are active in warmer temperatures while nuisance mosquitoes are more active in milder temperatures.”

But fast-moving water and mountain runoff that came down faster than expected flushed mosquito larval sites making it difficult for West Nile carrying mosquitoes to harvest eggs, explained Dr. Chester Moore, a professor in the Microbiology, Immunology and Pathology department at CSU.

Each week, a combined effort between the Colorado Mosquito Control, CSU and the City of Fort Collins sets 43 traps and record the amount caught as well as the species and locations.

“We have technicians out frequently checking and treating larval sites to prevent hatching and to catch the WNV carrying Culex,” Calhoon said.

Of the testing done thus far, none have come back positive with West Nile Virus. Testing has also found fewer Culex mosquitoes than a typical bad year where Culex can test positive for West Nile as early as the first week in July, explained Moore.

“I don’t like to make predictions but our testing has suggested we aren’t at a serious danger for the West Nile Virus this year,” he said.

While testing hasn’t indicated any West Nile carrying mosquotes, it’s important to continue aggressive testing to be proactive if positives begin to appear, explained Schurich.

“We always need to be alert during the West Nile season even if we haven’t found positives,” Schurich said. “We also need to make sure that the public is aware of to protect themselves.”

For more information about the West Nile and tips for avoiding mosquitoes, visit www.larimer.org/health or call the Colorado helpline at 1-877-462-2911.

Staff writer Allison Knaus can be reached at news@collegian.com.

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