FARGO -- The Fargo-Moorhead area has some of the highest mosquito counts the metro has seen in decades, which is raising concerns about West Nile virus, experts said.

Cass County Vector Control recorded large mosquito counts as it checked its traps in recent weeks, Vector Control Director Ben Prather said. The trap counts are the highest Cass County has seen since 2005, he said.

That's likely because August brought more rain than normal, Prather said. Fargo recorded 3.31 inches of rain for the month, almost an inch more than average, according to the National Weather Service in Grand Forks. The month had several days of rainfall.

"We've had just one really strong shot (of precipitation)," Prather said. "In the past, we've had more rain consistently throughout the season, whereas this year, it's all just happened in the past ... couple of weeks."

Compared to several years of dry weather, 2025 rainfall and floodwaters presented optimal environments for mosquitoes, especially in the second half of August, he said.

Fargo isn't alone, said Amanda Bakken, an epidemiologist with the North Dakota Department of Health and Human Services. Vector control districts from around the state noticed an uptick in mosquito counts, she said.

"We have certainly heard lots of reports from individuals, as well as vector control, saying that there's a lot of mosquitoes this year," she said.

Because of the amount of rain the state recorded in August, the increase is not unexpected, but it is unfortunate, Bakken said. The rise in buzzing and annoying bugs that feed on human blood also increases the chances of North Dakota residents contracting West Nile virus, she said.

Minnesota and North Dakota issued news releases in recent weeks to alert the public to a rise in West Nile activity. As of Friday, Aug. 29, 59 North Dakotans contracted the disease, according to state Health and Human Services data.

That's the highest count since 2018, when the state reported 204 cases. According to data from the U.S. Centers for Disease Control and Prevention, North Dakota has the third-highest West Nile count behind Colorado and Arizona.

Minnesota reported 20 cases as of Aug. 26, according to its Health Department. Last year, the state reported 35 cases.

Elizabeth Schiffman, an epidemiologist supervisor at the Minnesota Department of Health, said she anticipated this year's West Nile count to approach 2023, when Minnesota confirmed more than 60 cases.

"Based on what we've seen so far, and the reports that are still coming in and that we're still investigating, I do anticipate that we're going to have a bigger year in terms of cases," she said.

Two people died from West Nile virus in Minnesota this year. No deaths connected to West Nile were reported in North Dakota.

Mosquitoes pick up the deadly disease from infected birds, according to the CDC. The insects then pass it on to humans, horses and other mammals through bites.

Late August is a peak time for West Nile, Bakken said. Each season presents cycles of small and large numbers, she said.

"We are having more than we certainly did last year," she said. "We are starting to see a bit of a slowdown in cases coming in. It's not profound at this point, and we don't know if that's going to hold, but things are starting to slow a little bit."

Humans and animals can't pass on the disease, according to the CDC. Most people who contract West Nile show no or mild symptoms, Schiffman said.

"We think that a lot of those people, they're not getting a diagnosis," she said. "They're not going to the doctor because they get better before they would want to go to the doctor. So, our data is kind of skewing itself toward those people that get sick enough that they end up seeking health care and then getting those diagnoses."

About 2,000 people report contracting the disease in the U.S. each year, with 1,200 developing severe symptoms and more than 120 dying, according to the CDC.

North Dakota is in the path of migrating birds that carry the virus, which amplifies residents' risk of infection, Bakken said. Minnesota's western counties, including Clay, Norman and Wilkin, have a high risk for contracting the disease, according to the Health Department. That area has open agricultural habitats and prairie where mosquitoes thrive, Schiffman said.

She and Bakken said they want people to protect themselves while enjoying the outdoors during the summer. That includes using insect repellent approved by the U.S. Environmental Protection Agency, wearing long-sleeved shirts and pants, limiting outdoor activities at dusk and dawn, eliminating stagnant water in yards, repairing window and door screens, and maintaining well-trimmed landscaping, the health departments said.

"There's still that risk of transmission until essentially the first frost," Bakken said. "Even though we have a peak in mid to late August, sometimes ... depending on the weather, we continue to get cases throughout September. It's always just really important to keep yourself protected against mosquitoes."