Orange County records 36 West Nile virus cases in 2026

Orange County health officials have confirmed 36 human cases of West Nile virus this year. The figure compares with one case during the same period last year and three cases reported for all of 2025.

As of September 24, the county had recorded no deaths attributed to West Nile virus. However, the family of a 61-year-old Anaheim man told ABC7 that he died this month after contracting the virus. His death has not yet been included in the county’s official statistics.

The rise in infections in one of Southern California’s most populous counties is a warning for households. Most infections cause no symptoms, but the illness can become severe in a small number of cases, with older adults and people with certain medical conditions facing the highest risk.

Cases surge across the county and state

The California Department of Public Health reported in August that West Nile virus activity had reached its highest level in five years. As of September 18, the state’s West Nile virus surveillance website listed 147 human cases and 10 deaths across 21 counties. At the same point last year, 117 cases had been reported.

State and county figures do not match. The state website listed 10 cases in Orange County as of September 18, while county officials reported 36 cases six days later. County figures are based on more recently updated information, while statewide statistics can lag behind local reports.

Mosquito testing also points to a sharp increase. A representative of the Orange County Mosquito and Vector Control District said on September 15 that 718 mosquito samples tested positive for the virus this year, up sharply from 70 during the same period in 2025. CBS Los Angeles reported this figure. “This year has been an extraordinary year for mosquitoes—it’s like the fire alarm is going off,” the representative said.

The district planned nighttime spraying against adult mosquitoes in Anaheim, Costa Mesa and Garden Grove. According to the representative, the ultra-low-volume treatment is applied at roughly two tablespoons per acre and is not harmful to people when used at that concentration.

As of September 18, all 10 deaths recorded statewide had occurred in the Central Valley counties of Butte, Glenn, Kings, Sacramento and Yolo. If the Anaheim death is confirmed, it would be Orange County’s first officially recorded West Nile virus death in 2026.

Family warning after an unrecorded death

Daniel Clavel, an Anaheim resident, became ill in August, ABC7 reported. He developed a rash and was later found unconscious at home. After spending 24 days in intensive care, he died.

“When he left us, he wanted people to be warned,” his wife, Tracy, told the television station.

As of September 24, county officials had not included his death in the West Nile virus statistics. Investigating a death and adding it to the official count can take time. Until the county updates its figures, the death remains based on the family’s account rather than official statistics.

People over 50 and those with chronic conditions face higher risk

About one in five infected people develop symptoms such as fever, headache, body aches, nausea and fatigue, county officials said. In far fewer cases, the infection causes neuroinvasive disease affecting the brain and spinal cord. Symptoms may include severe headache, neck stiffness, confusion, muscle weakness and paralysis.

“West Nile virus is regularly present in Orange County, with activity occurring every summer and continuing into the fall,” county Health Officer Dr. Regina Chinsio-Kwong said on August 5, when announcing the county’s first human case of 2026.

County officials warned that people over 50 and those with certain medical conditions are more likely to develop severe illness. Older relatives, people with chronic conditions such as diabetes or high blood pressure, and those with weakened immune systems should take extra precautions—particularly if they spend time outdoors in the evening or live near standing water.

There is currently no vaccine to prevent severe West Nile infection and no specific treatment for the virus. Severe cases are treated by managing symptoms, making mosquito-bite prevention the main line of defense.

A significant share of reported infections nationwide are also severe cases. MedicalDaily previously reported that seven of every 10 West Nile virus cases reported this year had neurological involvement. This is partly because the most seriously ill patients are more likely to be tested, but it also illustrates how common severe illness is among reported cases.

“People need to be vigilant,” the district representative told ABC7, urging anyone outdoors around dawn or dusk to use insect repellent.

Mosquito season is not over

County health officials said the risk has not declined because the virus spreads during summer and early fall. Residents are advised to drain standing water from places such as flowerpots and pet water bowls, keep window and door screens in good condition, and use mosquito repellents registered with the U.S. Environmental Protection Agency that contain DEET, picaridin, oil of lemon eucalyptus or IR3535.

Wearing long-sleeved shirts and long trousers, and limiting time outdoors around dawn and dusk, can also reduce the risk. Residents with mosquito-related concerns can contact the Orange County Mosquito and Vector Control District.

Anyone who develops a sudden severe headache, neck stiffness, confusion or weakness after a mosquito bite should seek emergency medical care. Even mild fever or body aches are reasons to consult a doctor, particularly for older adults and people with chronic conditions.

September 24, 2026: Orange County had recorded 36 human cases and no officially recorded deaths. The family of an Anaheim man told ABC7 that he died after contracting West Nile virus.

September 18, 2026: California had recorded 147 cases and 10 deaths.

August 5, 2026: An Anaheim resident became Orange County’s first human case of 2026.

Key questions answered

How many West Nile virus cases have been recorded in Orange County? As of September 24, county officials reported 36 human cases. There had been one case during the same period last year.

Has anyone died? No deaths were listed on the county’s official website. The family of an Anaheim man told ABC7 that he died after contracting the virus, but his death had not been added to county statistics as of September 24.

Why do the state and county figures differ? County data are more up to date, while statewide statistics may lag behind local reports.

Who faces the greatest risk? People over 50 and those with certain medical conditions.

What are the symptoms of severe illness? Severe headache, neck stiffness, confusion, muscle weakness and paralysis.

How can families protect themselves? Drain standing water, use registered mosquito repellent, repair window and door screens, cover exposed skin with clothing, and limit time outdoors around dawn and dusk.