Current WNV Positive Cases 2021 (updated Oct. 28, 2021)
The first positive cases of West Nile Virus for the 2021 season were three American Crows from Chemung county submitted the first week of July, testing returned positive on all three on July 9, 2021.
Current WNV Positive Cases 2020 (updated Feb. 1, 2021)
|1/29/21*||American Crow||Erie||*Submitted 8/10/20, tested 1/29/21|
|1/29/21*||American Crow||Erie||*Submitted 9/16/20, tested 1/29/21|
|11/4/20*||Bald Eagle||Genesee||Euthanized 9/23, submitted 11/4|
|10/30/20*||Bald Eagle||Broome||Received 9/1, submitted 10/30|
|9/9/20||Great Horned Owl||Onondaga|
The first positive West Nile Virus of the 2020 season was a juvenile American Crow from Suffolk county submitted on July 20. While this first case it a little later than normal based on 2017-2018 results, it is earlier than last year's start, which was early August when we saw our first positive case and that was an American crow as well.
Current WNV Positive Cases 2019 (updated Sept. 12, 2019)
We are well into the 2019 mosquito season and have been holding our breath waiting for the first West Nile Virus case to come through. Almost one month later than our first case seen last year (7/10/2018), we have received our first WNV positive result of 2019. An American crow from Tompkins County was found dazed and close to people and submitted to the Janet L. Swanson Wildlife Health Center for assessment, the bird died the same day. Blood was submitted to CWHL for testing and returned positive WNV results today. Please see listings below for historical results. Raptors and crows are particularly sensitive to West Nile infections, and crows have a high mortality rate. Other species may have mild or no symptoms from infection.
Current WNV Positive Cases 2018 (updated October 26, 2018)
|7/19/2018||Great Horned Owl||Tioga|
|7/21/2018||Red-Tailed Hawk *Suspect-WNV||Tompkins|
|8/2/2018||Broad-Winged Hawk *Suspect-WNV||Tioga|
|8/1/2018||Great Horned Owl||Herkimer|
|9/11/2018||Red-Tailed Hawk *Suspect-WNV||Dutchess|
|9/11/2018||Red-Tailed Hawk *Suspect-WNV||Cortland|
|9/12/2018||Red-Tailed Hawk *Suspect-WNV||Chemung|
|9/17/2018||Great Horned Owl||Chemung|
Original Post-July 17, 2018
This is mosquito season, and along with that comes cases of West Nile Virus. A red-tailed hawk from Steuben County is the first avian case of 2018. This first case is later than last year but about average compared to previous years (see historical info below). The bird was found down and was taken to the Janet L. Swanson Wildlife Health Center for assessment. Blood was submitted to CWHL for testing and returned positive WNV results late last week. The bird is alive and receiving supportive care at the clinic. Raptors and crows are particularly sensitive to West Nile infections, and crows have a high mortality rate. Other species may have mild or no symptoms from infection.
Historical WNV testing data from the New York State Wildlife Health Program
|Year||First Case||Last Case||Total Positive Cases|
|2020||July 24||September 1||8|
|2019||April 10||September 27||10|
|2018||July 10||October 8||88|
|2017||April 25||November 26||195|
|2016||July 8||October 4||35|
|2015||June 11||October 9||38|
|2014||July 1||September 16||12|
|2013||June 23||October 24||92|
|2012||July 6||October 23||104|
|2011||July 20||October 6||33|
New York City has recently reported a human West Nile case and a number of positive mosquito pools. No human cases have been reported from the rest of the state, and mosquito surveillance is up to the individual counties, many of which don't conduct mosquito pool testing. However, West Nile is presumed to be widely active around New York during the summer and fall.
In 2017, the CWHL reported a marked increase in WNV positive results over previous years. Our data collection is being used to study how and why these year to year fluctuations occur. Environmental factors like winter temperature, rainfall amounts and timing, and the mosquito species that are active all affect the prevalence rates.