RIVERSIDE (CBSLA.com) — Authorities on Saturday were spraying to control mosquito activity  in Riverside in response to increased West Nile Virus activity.

The Northwest Mosquito and Vector Control District conducted “ultra-low volume ground applications, using truck mounted sprayers to reduce the risk of disease transmission to humans by adult mosquitoes,” the agency said, between 3 a.m. and 5 a.m. in the Canyon Crest area of Riverside. Spraying was also conducted Friday in Norco and Corona.

Sixteen human cases of West Nile Virus in Riverside County have been confirmed by public health officials, including a 77-year-old western Riverside County man who died last week after falling ill from other health complications. Five West Nile Virus-related deaths have been reported throughout the state this year, according to the California Department of Public Health.

West Nile Virus is transmitted through the bite of an infected mosquito. Many infected individuals will not experience illness or may have mild symptoms such as fever, headache and body aches. Young children, the elderly and individuals with lowered immune systems are at greater risk of experiencing severe symptoms after infection.

To report mosquito problems, neglected pools, standing water or dead birds, contact Vector Control at (951) 340-9792.

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