Surge in West Nile virus activity expected to rise in Sacramento this summer

West Nile virus activity is expected to surge in the Sacramento area as the summer progresses, authorities said.

“As temperatures continue to rise, we expect mosquito populations and West Nile virus activity to increase throughout the summer,” said Gary Goodman, manager of the Sacramento-Yolo Mosquito and Vector Control District, in a Wednesday, June 24, news release.

Six mosquitoes and three dead birds have tested positive for the virus so far in 2026.

“These positive mosquito samples and birds serve as an important reminder that residents should take steps now to reduce mosquito breeding around their homes and protect themselves from mosquito bites,” Goodman said.

The mosquitoes and birds with the virus have mainly been found in the Carmichael and Tahoe Park areas, the agency said.

The district will continue to monitor West Nile virus activity.

This month, health officials in Placer County identified that county’s first West Nile virus-positive bird of 2026.

What to know about West Nile virus

West Nile virus is a mosquito-borne disease, the U.S. Centers for Disease Control and Prevention said.

Each year, about 2,000 people in the United States are diagnosed with West Nile virus, the Centers for Disease Control and Prevention said. But this is an underestimate as many people do not recognize or report the illness.

There were 113 confirmed human cases of West Nile virus in California in 2025, eleven of them fatal.

The virus “almost always” spreads to humans through the bite of mosquitos that have been infected by feeding on the blood of birds with the disease, the California Department of Public Health said.

Most people have no symptoms, but mild symptoms include fever, headache, body aches, skin rash on trunk of body and swollen lymph glands.

Severe symptoms can include headache, high fever, neck stiffness, impaired consciousness, extreme lethargy, and reduced reactivity to outside stimuli, disorientation, coma, tremors, convulsions, muscle weakness and paralysis. Complications can include death.

How to prevent West Nile virus

“The best way to prevent WNV is to protect yourself from mosquito bites,” the California Department of Public Health said.

Other tips include:

• Drain standing water that can harbor mosquitoes.
• Avoid being outdoors at dawn and dusk.
• Wear long sleeves and pants when outdoors.
• Defend yourself by using an effective insect repellent.
• Make sure to follow label directions.
• Keep door and window screens in good working order.
• Residents can report dead birds by calling state health officials at 877-WNV-BIRD (877-968-2473) or by visiting westnile.ca.gov.