Dean Fioresi is a web producer for CBS Los Angeles. He covers breaking news throughout Southern California. When he's not writing about local events, he enjoys focusing on sports and entertainment.

The Los Angeles County Department of Public Health announced the first human cases of West Nile virus in a resident on Wednesday.

They said that four people were hospitalized with the virus between late July and August, in a news release. The patients lived in central Los Angeles and the Antelope and San Fernando valleys, officials said.

"The first human cases of West Nile virus are an important reminder that we all need to take steps to prevent mosquito bites and mosquito breeding," said Los Angeles County Health Officer Dr. Muntu Davis. "Mosquitos thrive in hot weather, increasing the risk of bites and mosquito-borne disease."

West Nile virus spreads through the bite of an infected mosquito, LADPH officials said. Typical symptoms include fever, headache, nausea, body aches and a mild skin rash. For some people, the virus can affect the nervous system and result in paralysis, encephalitis, meningitis or death, the LADPH release said.

Officials noted that everyone is at risk for West Nile virus, but adults over 50 and people with chronic health problems are at higher risk of developing severe illness.

"Although not all mosquitoes carry this virus, the type of mosquito that spreads this virus is found throughout Los Angeles County," the release said.

Davis advised residents to take a series of steps to reduce exposure to mosquitoes, including use of insect repellants, removing items that hold standing water and installing door and window screens to prevent them from entering homes.

Over the last five years, Los Angeles County has reported an average of 56 cases of West Nile Virus, officials said. They believe that the number is much higher, as most infected people do not experience illness or only suffer from mild symptoms.

Los Angeles County reports first West Nile virus cases of the year