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West Nile Virus

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Protect Yourself with the Four D's!

Diagram of the 4 D's - Drain, Defend, Dress, and Dusk till Dawn
  1. Drain: Mosquitoes breed in water! Drain any standing water in your yard each week. Bird baths, clogged gutters, and kiddie pools are common breeding sites.
  2. Dress: Wear lightweight, long-sleeved shirts and long pants while outdoors. Spray clothing with insect repellent since mosquitoes may bite through clothing.
  3. Defend: Apply insect repellent sparingly to exposed skin. Use an approved repellent according to its label. Find the repellent that is right for you.
  4. Dawn/Dusk: Limit time spent outdoors at dusk through dawn, when mosquitoes are most active and feeding.

Learn More

Weekly Vector Index

In addition to a recommendation by the Larimer County Department of Health, spraying will commence in any treatment zone where the vector index meets or exceeds 0.75. In order to best target infected mosquitoes, treatment zones are based on current data and are often different, smaller, or may cross quadrant boundaries. 

WNV vector index levels updated weekly, June 17 through September 8, 2019.

Last updated: August 12, 2019. Next scheduled update: August 19, 2019

VECTOR INDEX (map of quadrants):

NW Quadrant: 0.13   
NE Quadrant:  0.09     
SE Quadrant:  0.14   
SW Quadrant: 0.15 

Vector Index levels for quadrants are provided to alert the community to the threat of WNV in large areas of the city. Recommendations to spray for adult mosquitoes are made by the Larimer County Health Department, and are based on data from at least a 5 trap area. The City operates a network of 53 traps providing weekly data on the level of WNV in targeted areas. 

Interested in how the Vector Index is calculated? Find more information from the Centers of Disease Control here.


Most recent three week's trap data:

LETA WNV Spraying Alerts

Diagram of the 4 D's - Drain, Defend, Dress, and Dusk till Dawn

In the event that the City of Fort Collins decides to spray for mosquitoes, you can sign up for community alerts at Larimer Emergency Telephone Authority (LETA911). 

Email or Phone Call Alerts: Create an account and under "My Alert Subscriptions" click "Community Alerts" and then check the "Fort Collins | Poudre Fire Authority" box and check "West Nile Virus Spraying" to receive alerts.

Text Alerts: To receive a text message alert, simply text FCWNV to 888-777. 

LETA911 is the Governing Authority for 9-1-1 in Larimer County, Colorado. LETA911 provides oversight to 9-1-1, the equipment, and the programs funded by LETA. This includes non-emergency or community alerts for WNV adulticiding. 

Register for LETA911

New Interactive Mosquito Surveillance & Control Map

Map of mosquito surveillance and control

Our mosquito control contractor, Vector Disease Control International, has a NEW interactive mosquito surveillance and control map.

View Map

Businesses Can Apply To Opt Out Of Spraying

Sign that says 'Organic Ranch Do Not Spray Pesiticides'

If you are a business or laboratory you can apply to opt out of our adulticiding (spraying operations). Please keep in mind only commercial businesses able to prove a long-term negative financial impact on their business will be considered. To apply, enter your business and contact information. Applicants will receive an application via email with the requirements and details of the opt-out.

Apply to Opt Out

West Nile Virus Risk Map

View the West Nile Virus Risk Map to understand where testing indicates the presence of West Nile virus positive mosquitoes. The City of Fort Collins operates 53 traps throughout the community to provide up to date information on the severity of West Nile virus.

West Nile Virus Technical Advisory Committee

West Nile Virus committee meeting and writing on white board

The West Nile Virus Technical Advisory Committee meets to discuss the previous mosquito season and considers recommendations for future response guidelines. The committee is composed of City-appointed experts who provide technical expertise and make recommendations to City Council regarding the City’s West Nile Virus Management Policy. Visit their webpage for meeting minutes and to get notifications when new minutes are available.

Upcoming Meetings:

  • January 15, 2020
  • February 19, 2020
  • March 18, 2019
  • April 15, 2020

Meetings are held from 4:30 - 6:00 PM in the Parks Department Conference Room, 413 S. Bryan Ave.