Weld and Boulder counties reporting presence of West Nile virus

Though Larimer County has not yet detected infected mosquitoes, as of the traps collected last week, the risk of being bitten by a mosquito carrying West Nile virus is rising in Larimer County.

Weld and Boulder Counties, both of which border Larimer County, have confirmed the presence of Culex mosquitoes infected with West Nile virus, as well as Adams, Delta, and Mesa counties. This level of West Nile-infected mosquitoes is usually not seen until July.

“This spring has been very wet and warm, and now we have standing water that is perfect for Culex breeding,” said Rich Grossmann, environmental health specialist for the Larimer County Health Department. “They really increase their numbers as the temperatures rise.

“If infected mosquitoes are in our neighboring counties, they are likely here and will be detected in Larimer County traps soon,” Grossmann said. “It’s definitely time to do what you can to prevent being bitten by mosquitoes.”

Steps individuals can take for prevention include:
• Use an effective mosquito repellent when outside, especially between dusk and dawn or on cloudy days, or dress in long sleeves and pants. Apply repellent to all exposed skin. Read the label before applying to adults and to children; depending on the concentration of the repellent, you made need to reapply it after a couple hours.
• The Centers for Disease Control recommends using repellents containing DEET, Picaridin, Oil of Lemon Eucalyptus (also called p-Menthane-3,8-diol), or IR3535; these repellents have been shown to be effective against Culex mosquitoes when used as directed.
• Eliminate mosquito breeding areas around your home such as containers of standing water, and treat backyard ponds with a mosquito “dunk” or add mosquito-eating minnows to the pond.
• Empty standing water in bird baths, pools, etc., at least weekly—twice a week when temperatures are over 90 degrees and mosquitoes can grow from eggs to biting adults in only 5 days.
• Repair all house screens and screen doors. A blood-seeking mosquito needs only a fraction of an inch gap to enter your home.
• Direct one or more strong fans at the seating area of your deck or patio. The brisk breeze makes it harder for mosquitoes to fly nearby and land.

For information on West Nile virus and safe use of mosquito repellents, go to

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