Glenn County has confirmed its second West Nile virus death of 2026, a resident between 70 and 80 years old who died of complications from the infection, the county's Health and Human Services Agency announced, KRCR reported on Sept. 17. The death brings the number of West Nile fatalities reported to the state this year to 10.
All 10 deaths come from five counties: Butte with three, Glenn, Sacramento, and Yolo with two each, and Kings with one, according to the California Department of Public Health's West Nile tracker. All five counties are in the Central Valley. Glenn, a small rural county north of Sacramento, has reported six human cases, and two of those patients have died.
For families caring for an older parent in the Sacramento or San Joaquin valleys, that pattern turns a statewide number into a household decision. The state has not explained why the deaths cluster there, and small counts can shift quickly from week to week. The risk profile, however, is consistent: severe illness falls hardest on older adults and people with chronic conditions, and the peak transmission season is not over.
A Season Already Past Last Year's Total
California has now logged 147 human cases across 21 counties, including 25 added in the latest weekly report from 12 counties ranging from Butte and Fresno to Los Angeles and Orange. That already surpasses the 117 cases and 11 deaths recorded in all of 2025, according to the state's historical summary. Los Angeles County leads with 44 cases, followed by Fresno with 16 and Butte with 14.
The environmental signals are stronger. The virus has turned up in 3,544 mosquito samples from 29 counties and in 623 dead birds from 24 counties. The bird count is about four times last year's full-year total of 154, and the mosquito figure tops every full year on record except 2023. In August, the state reported virus activity at a five-year high, with more than 24% of tested dead birds positive, compared with a five-year average of 13%.
Human cases tell a more measured story. The current total remains below the 2021 to 2025 full-year average of about 204 cases, based on a MedicalDaily calculation from state data. Reported cases also undercount infections, because most infected people never feel sick or get tested.
MedicalDaily's earlier report on six deaths and 86 cases, based on state data through Sept. 4, tracked the season's early climb. Since then, the state has added 61 cases and four deaths.
One discrepancy remains unresolved. Los Angeles County announced its first 2026 death on Aug. 20, a San Fernando Valley resident hospitalized with neurological illness, NBC Los Angeles reported. Los Angeles County does not appear on the state's current death list, and CDPH has not publicly explained the difference. The state's multiyear summary table also still shows zero 2026 deaths, even though its weekly update lists 10.
Older Adults and Chronic Illness Drive the Severe Cases
Glenn County officials said about 80% of infected people have no symptoms, about 20% develop mild illness such as fever, headache, or rash, and fewer than 1% develop severe illness affecting the central nervous system. The risk of life-threatening complications rises for people over 50, those with diabetes, kidney disease, or high blood pressure, and people with weakened immune systems, including cancer patients and organ transplant recipients. CDPH lists adults 60 and older and people taking immune-suppressing medications among those at highest risk.
"We are saddened to announce another WNV-related death," said Dr. Jared Garrison, Glenn County's health officer. Yolo County's first death this year, announced Sept. 8, involved neuroinvasive disease, the most severe form, CBS Sacramento reported. Yolo County Health Officer Dr. Joanna Locke said older adults, people with weakened immune systems, and people with certain underlying conditions face greater risk of severe illness.
Key details remain unknown. The state has not released ages, exposure locations, or health histories for most of the people who died, so it is not possible to say whether access to care, outdoor work, or chance explains the Central Valley cluster. Sacramento County has reported 11 cases and two deaths. Gary Goodman, district manager of the Sacramento-Yolo Mosquito and Vector Control District, said virus activity remains elevated across the region as it enters the time of year when mosquito numbers typically stay high.
Warning signs of severe illness include high fever, stiff neck, confusion, and muscle weakness. Anyone with those symptoms, particularly an older adult, should get urgent medical care. There is no human vaccine or specific treatment for West Nile virus, so care focuses on managing symptoms.
Prevention costs little. Health officials recommend an EPA-registered repellent with DEET or picaridin, long, loose clothing outdoors, and extra caution at dawn and dusk, when mosquitoes bite most. Emptying standing water in plant saucers, pet bowls, and buckets removes breeding sites, and Glenn County suggests mosquitofish for water that cannot be drained. Residents can find their local vector control agency by ZIP code on the state website and report dead birds at 1-877-968-2473.
"August and September are peak periods of West Nile virus transmission in the state," CDPH Director Dr. Erica Pan said in August. The state updates its figures every Friday, with the next report expected Sept. 25. Because diagnosis and reporting lag behind infection, totals may keep rising into October even as nights cool.
Developing Story Timeline
Sept. 18, 2026, 5:33 p.m. PT: CDPH reports 147 human cases in 21 counties and 10 West Nile-related deaths from Butte, Glenn, Kings, Sacramento, and Yolo counties.
Sept. 17, 2026: KRCR reports that Glenn County has confirmed its second West Nile-related death, a resident aged 70 to 80.
Sept. 8, 2026: Yolo County Public Health announces the county's first 2026 death, involving neuroinvasive disease.
Sept. 4, 2026 (data-through date): MedicalDaily's earlier report counts six deaths and 86 cases statewide.
Aug. 20, 2026: Los Angeles County confirms its first West Nile death as CDPH reports statewide activity at a five-year high.
Key Questions Answered
How many West Nile deaths has California reported in 2026?
CDPH lists 10 West Nile-related deaths and 147 human cases from 21 counties as of Sept. 18, 2026.
Which counties reported the deaths?
The state's list includes Butte (3), Glenn (2), Sacramento (2), Yolo (2), and Kings (1), all in the Central Valley. Los Angeles County announced a death in August that does not appear on the current state list.
Who faces the highest risk of severe illness?
Older adults, people with diabetes, kidney disease, or high blood pressure, and people with weakened immune systems, such as cancer patients and transplant recipients.
What symptoms should people watch for?
Most infections cause no symptoms. Mild illness can include fever, headache, and rash. High fever, stiff neck, confusion, or muscle weakness can signal severe disease and need urgent care.
How can residents protect themselves?
Use an EPA-registered repellent with DEET or picaridin, wear long, loose clothing, limit time outdoors at dawn and dusk, drain standing water, and keep window screens in good repair.
When will new numbers be released?
CDPH updates its West Nile figures every Friday. The next update is expected Sept. 25, 2026.
