People 50 and older are more likely to become seriously ill from the virus. Symptoms of severe illness include high fever, neck stiffness, disorientation, coma, tremors, paralysis and death. There is no specific therapy for West Nile encephalitis. Seven deaths were reported. Seventeen cases have been reported this year, including one death.
Officials say that disrupting the mosquito breeding areas helps stop the virus.
People should take steps such as emptying stagnant water from flower pots and other containers and treating private swimming pools with appropriate chemicals.