HomeMy WebLinkAboutMemo - Mail Packet - 07/08/2025 - Memorandum from Ryan Vincent re West Nile Virus – Weekly ReportNatural Areas Department
1745 Hoffman Mill Road
PO Box 580, Fort Collins, CO 80522
970-416-2493
rvincent@fcgov.com
CC: Mike Calhoon, Parks Director; Katie Donahue, Natural Areas Director; Matt Parker, Natural Areas Ecological
Stewardship Manager 1
MEMORANDUM
Date: July 1, 2025
To: Mayor and City Councilmembers
Through: Kelly DiMartino, City Manager
Tyler Marr, Deputy City Manager
Dean Klingner, Community Services Director
From: Ryan Vincent, Natural Areas Sr. Supervisor
Subject: West Nile Virus – Weekly Report
BOTTOM LINE
This information is intended to help City Council respond to community questions or concerns
about West Nile Virus (WNV) as they arise.
• West Nile virus-positive mosquitoes were detected in two traps this week- one in the
southeast quadrant of the city and one in the northwest.
• The citywide vector index is higher than average for this time of year.
• Larimer County Department of Health and Environment does not recommend
spraying at this time because the 0.75 floating zone threshold is not met.
WNV ACTIVITY ACROSS THE CITY
Week 26 of 37
Zone Previous Week VI* Current VI* Previous Week
Positive Traps
Current Week
Positive Traps
NW 0.00 0.10 0 1
NE 0.00 0.00 0 0
SE 0.12 0.06 2 1
SW 0.00 0.00 0 0
Citywide 0.04 0.05 2 2
Floating Zone NA 0.35 NA NA
*VI Threshold for spraying in a five-trap floating zone is 0.75
Docusign Envelope ID: 42783916-C6F4-451B-A9E0-12F92C846361
2
WNV ACTIVITY COMPARED TO HISTORICAL AVERAGES
While the abundance of Culex mosquitoes (the carriers of WNV) is below average, the vector
index is higher than average. Three weeks of data show an earlier than average start to the
West Nile Virus season.
NEXT STEPS
• Vector Disease International, the City’s contractor, is actively monitoring mosquito
breeding sites and treating larvae when appropriate.
• City staff will continue sharing updates with the community through fcgov.com/westnile
and social media.
• Staff will share West Nile Virus reports with Council to highlight trends and provide
advance notice of any planned mosquito spraying.
Docusign Envelope ID: 42783916-C6F4-451B-A9E0-12F92C846361