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News Archive

July 20, 2017

Mosquito Pool in Lafayette Tests Positive for West Nile Virus

Remember the 4Ds to stay safe and prevent illness

Boulder County, Colo. - Boulder County Public Health has confirmed that mosquitoes in Lafayette have tested positive for West Nile virus (WNV). The positive mosquito pool came from a trap in the northern portion of the Waneka Reservoir near Waneka Lake Park.

WNV is transmitted to humans from the bite of an infected mosquito. While most infections are mild, the more serious infections can cause encephalitis (inflammation of the brain) and/or meningitis (inflammation of the brain's lining), loss of vision, paralysis, coma, tremors, convulsions, and death.

Symptoms of WNV include fever, extreme fatigue, headache, body aches, and can also include skin rashes and swollen lymph nodes. Generally, symptoms appear 3 to 14 days after being bitten by an infected mosquito. Anyone who experiences these symptoms should consult their health care provider.

There is no treatment, cure, or human vaccination for the virus. Health care providers can only treat the symptoms to help patients feel better and possibly recover more quickly.

“Taking the appropriate steps to protect ourselves and loved ones is the best thing we can all do to prevent illness,” said Marshall Lipps, Boulder County Public Health environmental health specialist. “High temperatures and wet weather create an ideal environment for mosquitos to breed.”

Boulder County Public Health officials urge residents to take necessary precautions, known as the 4Ds, to protect themselves:

  1. Use DEET-enhanced insect repellent or alternatives, including Bite Blocker, Picaridin, oil of lemon eucalyptus, or IR3535.
  2. DRESS in long sleeves and pants.
  3. Avoid the outdoors from DUSK until DAWN.
  4. DRAIN standing water outside your home.

Mosquito season generally lasts from late April until mid-October, typically ending with the first freeze in the fall. There were 23 human cases of West Nile virus reported in Boulder County in 2016.

For more information about West Nile virus, mosquito activity in Boulder County, or steps you can take to protect yourself and loved ones, visit