As summer months bring warmer weather and heavier rainfall across the U.S., West Nile virus (WNV) cases are being reported with greater frequency.
As of July 1, 24 human disease cases of WNV have been reported in the U.S., according to the CDC. West Nile virus (WNV) is an arthropod-borne virus (arbovirus) spread by the bite of infected mosquitoes.
Here’s a look at recent West Nile virus reports from a variety of media sources compiled by the PCT staff:
Ohio
Poland: Mahoning County Public Health (MCPH) detected West Nile Virus in some mosquitoes in the area. According to a press release, the virus was detected in mosquitoes caught in a surveillance trap in the township. MCPH says while this detection was specific to Poland Township, the virus could be present anywhere in Mahoning County.
So far in 2025, there have not been any reported cases of West Nile Virus in humans in Mahoning County. The virus becomes more prevalent in mosquito populations in the late summer and early fall months. – WFMJ
Cleveland: The Medina County Health Department has received confirmation that a mosquito sample taken from a surveillance trap at the Susan Hambley Nature Center in Brunswick has tested positive for the West Nile virus. As part of a statewide mosquito surveillance program, the health department collects weekly samples from locations throughout the county. – Cleveland.com
Louisiana
New Orleans: In response to an increase in mosquito samples testing positive for West Nile virus (WNV), the City of New Orleans Mosquito, Termite and Rodent Control Board (NOMTRCB) conducted targeted mosquito spraying this week in several neighborhoods.
Officials say the spray treatments are a proactive effort to stop the cycle of West Nile virus, which is commonly spread between birds and mosquitoes and can infect humans through mosquito bites. So far, no human cases have been reported in Orleans Parish this year, but surveillance data indicates an elevated number of WNV-positive mosquito samples across the city.
Colorado
Denver: Health officials in Weld and Boulder counties announced this week they had confirmed detections of the virus, just days after Denver health officials confirmed they, too, had found a mosquito that tested positive for West Nile.
So far, Colorado has confirmed four positive results of the virus in mosquito traps this year – an early start to the season after Larimer County confirmed a detection of the virus on June 23, according to statewide data.
The Colorado Department of Public Health and Environment (CDPHE) shows the West Nile season in the state typically begins around mid-July and peaks about a month later, but state health officials say cases can be identified as early as May and as late as December, with the state’s first freeze usually signaling the end of the season. – ABC Denver 7
California
Sacramento County: Vector control officials announced Wednesday their first positive mosquito sample test for West Nile virus in the Sacramento area this season. The positive sample came from the Gibson Ranch area near Elverta.
California saw a total of 131 confirmed human cases of West Nile virus in 2024, officials say, with 12 deaths from the disease also reported. – CBS Sacramento
Texas
Houston: A man in Baytown contracted the mosquito-borne disease and has made a full recovery, according to Harris County Public Health. West Nile virus cases in the Houston area typically peak in the summer months, according to the health department.
Dr. Courtney Standlee, the interim director of the health department’s Mosquito and Vector Control Division, said earlier this week, the department collected 252,000 female mosquitoes so far this year in an effort to detect mosquito-borne diseases. In the field, inspectors set traps across Harris County to collect and test mosquitoes for a variety of viruses, including West Nile, Zika and dengue.
Last month, Harris County Public Health reported that a mosquito sample had tested positive for West Nile virus for the first time this year. – Houston Public Media
Frisco: The city of Frisco confirmed two mosquito pools tested positive for West Nile virus.
In response, the city is increasing surveillance efforts and intensifying “larviciding” in these two areas. The city will not spray at this time. – Frisco Enterprise
Illinois
The first human case of West Nile virus this summer has been confirmed in Illinois.
The Centers for Disease Control and Prevention confirmed that a person downstate, specifically in Southern Illinois, was hospitalized due to complications from West Nile.
This marks the earliest a West Nile case has been confirmed in Illinois since 2016. It also comes less than one week after the Illinois Department of Public Health announced it had found West Nile in 17 Illinois counties — including Cook, Will, and DuPage. – CBS News
New Mexico
Albuquerque: Warning comes as the City of Albuquerque Environmental Health Department has detected West Nile virus-positive mosquitoes through routine mosquito monitoring at locations throughout the city. – KRQE
