- Sacramento County reports its first human case of West Nile virus in 2026, following earlier detections in Long Beach and Alhambra.
- California has seen an unusually early and severe start to West Nile virus season, with 48 cases confirmed nationwide by June 30—the highest count since 2004.
- Health officials urge residents to use EPA-registered insect repellent, eliminate standing water, and wear protective clothing during dawn and dusk.
- Most infected people show no symptoms, but about 1 in 150 develop severe neuroinvasive illness, which can be fatal.
- No vaccine or specific treatment exists; prevention is the only defense.
First Human Case Confirmed in Sacramento County
Sacramento County health officials announced the county's first human case of West Nile virus for the 2026 season. The infected individual, a female in her 60s, was hospitalized with neuroinvasive illness and is now recovering at home. This case follows the first human infection reported in Long Beach in late June, marking an early escalation of the virus across California. As of June 26, this is the second human case reported statewide by the California Department of Public Health.
“This first human case this season is an important reminder that West Nile virus is actively circulating in our community,” said Sacramento County Public Health Officer Dr. Phuong Luu. “While most people who become infected will not develop serious illness, some people, especially older adults and those with a compromised immune system can experience severe complications. The best protection is to prevent mosquito bites by always wearing an effective mosquito repellent, wearing long sleeves and pants and eliminating standing water around your home.”
West Nile virus activity has increased significantly in recent weeks, with positive mosquito samples and infected dead birds found in multiple areas throughout Sacramento County. As of the latest update, Sacramento County has reported 1 human case, 31 dead birds, and 20 mosquito samples testing positive for West Nile virus.
“This human case confirms that West Nile virus is active and the risk to residents is increasing,” said Gary Goodman, Sacramento-Yolo Mosquito & Vector Control District Manager. “This comes at a time when residents will be enjoying the outdoor activities for the 4th of July holiday and it’s important for residents to stay protected because all it takes is one bite from an infected mosquito to get the virus.”
Practice the District D’s of Mosquito Prevention: Drain standing water, avoid being outdoors at dawn and dusk, dress appropriately, defend yourself with repellent, ensure doors and screens are in good condition, and contact district personnel for mosquito problems at 1-800-429-1022 or visit www.FIGHTtheBITE.net.
Unusually Early and Severe Season
The Centers for Disease Control and Prevention (CDC) reported at least 48 West Nile virus cases nationwide as of June 30—38 of them severe. This is the highest number for this time of year since 2004, when the agency began tracking. Twenty-three states have detected the virus, the most in a decade. Arizona leads with 32 cases, including four deaths in Maricopa County.
“These findings serve as an important reminder that mosquito season is well underway,” said Dr. Erin Staples, a CDC expert on insect-borne diseases.
Local Context: Sacramento and Southern California
In Sacramento County, the first human case adds to a growing list of detections. Earlier, the San Gabriel Valley Mosquito and Vector Control District found the virus in a mosquito trap in Alhambra. Long Beach reported its first human case on June 26, with the patient hospitalized for neuroinvasive disease. The southern house mosquito (Culex quinquefasciatus), native to Southern California, is the primary vector.
“West Nile virus is a recurring concern in our region because it is endemic to our area,” said Tristan Hallum, director of scientific programs for the San Gabriel Valley Mosquito and Vector Control District.
Risk Factors and Symptoms
Anyone can contract West Nile virus, but people over 50 and those with chronic health conditions face higher risks of severe illness. About 80% of infections cause no symptoms. The remaining 20% may experience fever, headache, body aches, nausea, vomiting, or rash. Less than 1% develop severe neuroinvasive disease—encephalitis or meningitis—which can lead to permanent brain damage, paralysis, or death.
“The key to staying safe and protecting your health is to prevent mosquito bites,” Hallum said.
Dr. Dean Blumberg, a UC Davis Health expert, elaborated on the virus's symptoms and potential severity. “Eighty percent of the time there's no symptoms, 20% of the time people can have symptoms and it's really a nonspecific illness. So people who are infected may have fever, muscle aches, joint aches, maybe vomiting diarrhea or a rash often occurs and most of them recover,” Blumberg said. He added, “You could die or even those who recover sometimes have chronic problems, such as fatigue or problems with memory or other neurologic issues.”
How to Protect Yourself
Health officials recommend the following steps:
- Apply insect repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus.
- Wear long-sleeved shirts and long pants during dawn and dusk.
- Eliminate standing water around homes—even bottle caps can breed mosquitoes.
- Install or repair window and door screens.
- Report increased mosquito activity to local vector control.
Blumberg emphasized the importance of mosquito prevention measures. “What works really well is mosquito repellent,” he said. “In your own home, if you decrease standing water, then you're going to decrease mosquito breeding grounds and decrease your risk of getting mosquito bites.” Luz Maria Robles of the Sacramento-Yolo Mosquito & Vector Control District said officials are actively working to control mosquito populations. “Since we noticed the steady progress of West Nile virus activity, we have been ramping up our surveillance efforts as well as our spraying,” she said. Officials also suggest wearing clothing that covers more of the body to avoid mosquito bites, though they acknowledge this may be challenging during hot summer days. There are no specific antiviral treatments for West Nile virus, but doctors can diagnose the illness through tests such as a spinal tap.
Conclusion
As West Nile virus season intensifies, Sacramento County residents must take proactive measures to reduce mosquito exposure. With no vaccine or cure, prevention is the only defense. Stay informed and protect your family by following health guidelines and eliminating breeding sites.