West Nile virus has claimed its first victim in Orange County this season, a Buena Park man who died a day after turning 80.

The man, who died Sept. 17, is among 28 Orange County residents to contract the disease this season, according to the Health Care Agency.

Last year, a record outbreak infected 280 residents and killed nine.

Mosquitoes spread the virus to humans after picking it up from birds. An infectious mosquito bite can cause a range of symptoms, from none at all to fever and body aches to neurological illness. They can take a couple of weeks to appear. About 10 percent of people who develop neurological infection due to West Nile virus will die.

Most of the 28 patients infected locally this year live in central and north Orange County. Buena Park and La Habra have reported the most cases, with four each.

Eighteen patients had the nuerological form of the virus and two were blood donors who tested positive but did not have symptoms. Because most people with West Nile virus don’t show symptoms, the reported figures “greatly understimate” the number of infected residents, according to the Health Care Agency.

History teacher Lynda Cook, of Santa Ana, developed meningitis after contracting the virus this summer and was hospitalized for four days. She said walking from one room to another in her house felt like “walking a marathon.”

Officials with Orange County Vector Control ramped up efforts to kill mosquitoes to keep the virus at bay this year. They were scheduled to spray pesticides from a plane into some neighborhoods with high rates of the infected insects earlier this month, but canceled plans because they were unable to get a permit to fly over Disneyland Resort.

West Nile virus season typically runs from July to October or November, when the weather cools.

“It is important for people to remember that the end of summer does not mean the end of West Nile virus season,” the county’s health officer, Dr. Eric Handler, said.

Contact the writer: jchandler@ocregister.com and @jennakchandler on Twitter