(FOX40.COM) — Mosquito season is officially underway and experts said it’s here earlier than normal.

The Sacramento-Yolo Mosquito and Vector Control District confirmed the season’s first sample of mosquitoes has tested positive for West Nile virus.

“This is an early indicator that it might be a very busy season ahead,” Luz Maria Robles, a spokesperson for the Sacramento-Yolo Mosquito and Vector Control District, said.

The positive sample came just south of Tahoe Park in Sacramento. The district said the area’s warm weather and rain from a little while back helped create the perfect breeding ground for growing mosquito populations and a head start to the busy season.

“West Nile virus is a seasonal virus and it can infect birds,” Dr. Dean Blumberg with UC Davis Health said. “Then mosquitoes bite the birds. Then they bite other animals, including humans, and that’s how it’s transmitted.”

Dr. Blumberg said it’s rarely transmitted person-to-person. He said about 80% of the time, when someone is infected, they don’t show symptoms and their body heals itself.

Remaining cases will exhibit flu-like symptoms like a fever, muscle aches, vomiting or even a rash. However, in certain situations, it can be very serious — specifically for people older than 55 or those who are immunocompromised.

“The reason that we get concerned about it is that in 1 out of about 150 people who get West Nile virus, it can cause neurologic disease,” Dr. Blumberg said. “This can include meningitis and can also include encephalitis, actual more involvement of the brain and it can even result in paralysis.”

There is no vaccine for this seasonal virus, which is generally spread in the summer and into the early fall. Therefore, experts said the best prevention is avoiding mosquito bites altogether.

“The most important thing is making sure [residents] are not having stagnant water around their home,” Robles said. “Dumping out stagnant water is going to go a long way to ensure you’re not breeding mosquitoes.”

Dr. Blumberg also weighed in.

“Using a mosquito repellent is the mainstay of prevention,” Dr. Blumberg said. “The most effective one is the repellents that include DEET.”

Last year, there were 124 human cases of West Nile virus in California — 11 people died.

“The CDC estimates that for every case that is reported, there’s 30 to 70 cases that go unreported,” Robles said.

Experts said mosquitoes carrying the virus are most active during dawn and dusk, so moving forward into the summer, it’s important to be aware and prepared.

“Getting this information is a reminder to all of us that the season has started for West Nile virus, the danger is out there. And so it’s important for people to take protective measures.”

Sacramento’s mosquito surveillance program started collecting samples earlier this week and from now until October, they will get additional testing results twice a week.

Copyright 2026 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

For the latest news, weather, sports, and streaming video, head to FOX40 News.