HomeMy WebLinkAbout2020-100 End of 2020 West Nile Virus Mosquito SeasonDate: December 4, 2020 Report No. 2020-100
INFORMAL STAFF REPORT
TO MAYOR AND CITY COUNCIL
SUBJECT:
Provide notification of the end of the 2020 West Nile virus mosquito season.
DISCUSSION:
Based on mosquito trap results from the last several weeks, low temperature ranges, and results of
the West Nile virus (WNV) screening by the Texas Department of State Health Services (TDSHS)
and the University of North Texas (UNT), Denton staff members consider the 2020 mosquito
season complete. In accordance with the City of Denton’s Mosquito Surveillance and Response
Plan (MSRP), the West Nile Virus risk level will be reset to Risk Level Two and will remain at
that level until the start of the 2021 mosquito season. The following information is provided as a
brief summary of the 2020 season:
Trapping began on June 6 and ended on November 23.
Approximately 229 traps deployed for routine monitoring (samples sent to the TDSHS
for WNV testing and mosquito species identification)
Approximately 206 traps deployed for local testing for WNV (conducted by UNT)
Approximately 1,600 larvicide applications by the Drainage and Parks and Recreation
departments
Seventeen larvicide treatments distributed to citizens
Thirty-four mosquito traps tested positive for WNV. The earliest detection was on June
15, and the latest detection was October 29.
Three reported positive human cases within the City of Denton, all were neuroinvasive
WNV
Three ground-based neighborhood sprayings, using for the first time the organic pesticide
Merus 3.0, were conducted on September 9, September 11, and September 21
Two deaths reported within the City of Denton
The 2020 season was a very active season with onset in mid-June and a high number of positive
mosquito traps, unlike the pattern observed in 2019. The sampling of mosquitoes occurred for a
longer period of time due to the last WNV positive mosquito trapping occurring in late October.
Mosquito trapping started at the beginning of June and was extended until late November. The
first hard freeze, the typical weather indicator used as the ending of the WNV mosquito season,
was recorded on November 30.
There are many staff members across the organization involved in the City of Denton’s Mosquito
Surveillance and Response activities. These staff members include the Drainage Department,
Public Communication Office, Technology Services, Parks and Recreation, the Water Department,
and Watershed Protection. The Mosquito Surveillance and Response Program would not be
possible without the dedication and hard work of these staff members. The University of North
Date: December 4, 2020 Report No. 2020-100
Texas researchers (Dr. Jim Kennedy and his group of graduate students) worked diligently to
ensure mosquito monitoring efforts and local WNV testing was completed efficiently.
Staff will take an update to Council on the program before the start of the next mosquito season in
2021.
STAFF CONTACT:
Deborah Viera, Assistant Director of Environmental Services
940.349.7162
Deborah.Viera@cityofdenton.com