HOUSTON, Sept. 4 (Xinhua) -- The U.S. state of Oklahoma broke its record for West Nile virus cases in a single year, with 118 cases confirmed this year, officials said Tuesday.
The Health Department of Oklahoma on Tuesday reported two more deaths from West Nile virus. So far, seven residents in the state have died because of the virus.
West Nile virus cases have been reported in 24 Oklahoma counties, with Oklahoma County leading the list with 39 cases and Tulsa County with 29 cases, according to local TV channel NewsOn6.
Health experts warned that adults over the age of 40 are at the greatest risk of becoming seriously ill after an encounter with a mosquito carrying West Nile virus and urged people in the age group to regularly practice personal protection methods, such as using mosquito repellent.
Oklahoma reported a record 107 West Nile infections in 2007. Nine people in the state died of the virus that year.
This year is also the worst year for West Nile nationally since the virus was discovered in the United States in 1999, according to the U.S. Centers for Disease Control and Prevention. There have been 1,590 cases reported nationwide.
First identified in Uganda in 1937, West Nile virus is a mosquito-borne illness that leads to serious neurological disease in some cases. Its symptoms include sudden onset of fever, headache, nausea, dizziness and muscle weakness.