HomeMy WebLinkAboutMemo - Mail Packet - 6/29/2021 - Memorandum From Matt Parker And Mike Calhoon Re: Summary Of West Nile Virus Technical Advisory Committee (Tac) Work/ Background Of West Nile Virus
Natural Areas Department
1745 Hoffman Mill Road
PO Box 580
Fort Collins, CO 80522
970.416.2815
970.416.2211 - fax
fcgov.com/naturalareas
MEMORANDUM
DATE: June 22, 2021
TO: Mayor and City Councilmembers
FM: Matt Parker, Sr. Supervisor, Natural Areas
Mike Calhoon, Director, Parks
TH: Darin Atteberry, City Manager
Kelly DiMartino, Deputy City Manager
Tyler Marr, Deputy Director, IES
RE: Summary of West Nile Virus Technical Advisory Committee (TAC) Work / Background of
West Nile Virus
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Bottom Line:
West Nile Virus (WNV) is an ongoing threat to the health of community members. The City of Fort
Collins partners with the Larimer County Department of Health and Environment to mitigate the risk of
WNV through increasing public awareness, reducing mosquito larvae production, data collection, and
when necessary, applying adult mosquito control insecticide. The WNV Program was designed through
significant input from the US Centers for Disease Control and Colorado State University. This memo
outlines the City and County efforts, summarizes the off-season review of the WNV Technical Advisory
Committee, and provides a brief season outlook for 2021. Larimer County Health Director Tom Gonzales
will be providing a community report at the July 6 council meeting, providing further information related
to this topic.
Background on the City s WNV Program
WNV is transmitted by two species of mosquito (as many as 12 species exist in the area), but the virus is
sustained in the region by the bird population. Through the summer weeks the virus presence amplifies
within the avian community presenting increased risk to humans. To mitigate this risk, the City funds a
program to educate community members on personal risk-reducing behaviors, reduce larval sources
and production, and collect weekly data on mosquito abundance and WNV infection rate. With a
program budget of approximately $330,000, over half is used to inspect and treat larval sites. The
remaining program budget is predominately used to develop a series of weekly datasets on species
abundance and infection rates, based upon a network of 53 traps throughout the community.
As this dataset represents the location and severity of WNV presence, it also represents a weekly
depiction of human risk of contracting WNV. This data is used to calculate an index value, or Vector
Index. Previous Councils have adopted a specific Vector Index threshold beyond which emergency funds
could be used, in conjunction with a recommendation from the LCDHE, for the application of adult
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mosquito insecticide. Such an application typically occurs in half the years, with the last application
taking place in 2019.
Although mosquito production picks up with the rising river and warming temperatures, the species of
mosquitos transmitting WNV do not typically increase in abundance until later in the summer. In other
words, the mosquitoes currently pestering residents do not pose a WNV risk. The City s WNV Program is
not a nuisance mosquito program, rather a WNV mitigation effort. As the active WNV season begins in
late June, staff will provide weekly emails characterizing the current conditions and data.
The West Nile Virus Program has completed the annual off-season review process and is currently
beginning its operational season. Budget impacts will decrease general WNV outreach and awareness
efforts, however if an adult mosquito application is scheduled, application specific outreach will proceed
as in past years.
TAC Off-Season Review Summary:
The 2020-2021 WNV off-season review process focused on completing an inquiry into the potential use
of an alternative organically labeled pesticide. Given the required increased use rate, lack of improved
signal word, and decreased efficacy of the naturally derived product, the TAC did not support further
investigation of the product at this time. The WNV Program currently uses Aqua-Kontrol 30-30, which is
a permethrin-based product with a piperonyl butoxide (PBO) synergist. It is generally considered the
best practice insecticide.
Seasonal Outlook for WNV June through September:
Vector Disease Control International (WNV Program contractor) has hired staff and initiated their early
season process of training staff, identifying mosquito breeding areas, and treating larval populations as
necessary. Trapping and testing of mosquito populations will begin the week of June 21.
The National Oceanic and Atmospheric Administration (NOAA) climate prediction models indicate a
likelihood of hotter and drier than normal conditions through August. Coupled with higher-than-normal
spring precipitation rates and the associated vegetative growth, this mosquito season could be severe.
As water sources recede, avian species typically congregate leading to an increased amplification cycle
for the virus.
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