Nine more Oklahomans have been sickened with West Nile virus, according to numbers released Thursday through the state Health Department.
Oklahoma has seen 13 cases of West Nile virus this year, including one person who has died and nine residents who developed serious brain and tissue diseases.
So far, cases have been reported in Comanche, Canadian, Oklahoma, Cleveland, Rogers, Cherokee and Muskogee counties.
This year, the state has seen significantly fewer cases of West Nile virus, which sickens people after they're bitten by a mosquito carrying the virus.
By Sept. 12 of last year, eight Oklahoma residents had died as a result of West Nile, and 127 residents had been sickened. Among those who died, two were in Oklahoma County, three were in Tulsa County, one was in Seminole County and two were in Carter County.
About 80 percent of people who are bitten by a mosquito carrying the virus don't develop symptoms. If they do get sick, most cases of West Nile virus are mild.
However, so far this year, the majority of Oklahoma residents who have a confirmed case of West Nile virus have developed serious illness.
People older than 50 are generally at a greater risk of developing serious symptoms related to West Nile virus.
Less than one percent of people who are infected will develop a serious neurological illness such as encephalitis or meningitis, or inflammation of the brain or surrounding tissues, according to the Centers for Disease Control and Prevention.
This year, nine Oklahomans — who range in age from at least 10 years old to older than 80 — have developed neuroinvasive disease because of West Nile virus. Symptoms include headache, high fever, neck stiffness, disorientation, coma, tremors, seizures or paralysis, according to the CDC.
There is no cure or vaccine for West Nile virus. If a person is admitted to the hospital, a doctor generally can only treat their symptoms.
Public health officials have urged residents to take precautions against mosquitoes, emptying standing water around their homes and using mosquito repellent while outdoors.