HomeMy WebLinkAboutMemo - Mail Packet - 07/15/2025 - 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 7, 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.
• WNV-positive mosquitoes were detected in five traps this week.
• The citywide vector index remains 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 was not met.
WNV ACTIVITY ACROSS THE CITY
Week 27 of 37
Zone Previous Week VI Current VI Previous Week
Positive Traps
Current Week
Positive Traps
NW 0.10 0.00 1 0
NE 0.00 0.09 0 1
SE 0.06 0.17 1 3
SW 0.00 0.10 0 1
Citywide 0.05 0.11 2 5
Floating Zone NA 0.31* NA NA
*VI Threshold for spraying in a floating zone is 0.75
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2
WNV ACTIVITY COMPARED TO HISTORICAL AVERAGES
While the abundance of Culex mosquitoes (the carriers of WNV) is near average, the infection
rate and vector index are still higher than average. These trends suggest that spraying may be
recommended in the next three to four weeks.
NEXT STEPS
• Staff will meet weekly with the Larimer County Department of Health and Environment to
evaluate WNV risk and determine if spraying is necessary.
• Vector Disease Control International (VDCI), the City’s contractor, will continue to
actively monitor mosquito breeding sites and treat larvae when appropriate.
• Staff will share VDCI’s monthly report for June with the community via
fcgov.com/westnile. The report contains weather information, updates on larval control,
and surveillance data.
• Staff will continue to share West Nile Virus reports with Council and provide advance
notice of any planned mosquito spraying coordinated by the City.
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