RIVERSIDE COUNTY, CA — The Board of Supervisors Tuesday authorized the Riverside County Department of Environmental Health to join 11 other agencies throughout Southern California in a mutual aid agreement aimed at improving vector control operations targeting mosquito-borne threats and related public health risks.
In a 5-0 vote without comment, the board signed off on agency Director Jeff Johnson’s proposal to add environmental health to the mutual assistance compact for the upcoming fiscal year.
“Mosquitoes and other vectors do not recognize jurisdictional boundaries, and they can transmit diseases or cause discomfort to humans across regions,” according to an agency statement posted to the board’s agenda Tuesday. “The Southern California vector control districts recognize the risks of vector-borne disease transmission and the need to have an agreement to allow for joint efforts when necessary.”
The compact makes county environmental health personnel available — for compensation paid by the requesting agency — for operations conducted by the Antelope Valley Mosquito & Vector Control District, Coachella Valley Mosquito & Vector Control District, Compton Creek Vector Control District, Greater Los Angeles County Vector Control District, Long Beach Department of Public Health, Los Angeles County West Vector Control District, Eastvale-based Northwest Mosquito & Vector Control District, Orange County Mosquito & Vector Control District, San Gabriel Valley Mosquito & Vector Control District, Santa Barbara County Mosquito & Vector Control District and the Ontario-based West Valley Mosquito & Vector Control District.
“The residents of Riverside County will benefit from this agreement through improved protection from vector-borne diseases like West Nile virus,” Johnson said. “The agreement allows for quicker, coordinated responses to mosquito outbreaks and reduces the risk of disease transmission.”
No West Nile virus infections have been documented in Riverside County, or anywhere else in California, so far this year. In 2024, a total 151 infections — including six in Riverside County — were recorded statewide, according to the California Department of Public Health. There were a dozen WNV-related deaths throughout the state, one of which was in Riverside County.
Mosquitoes typically become carriers of the virus after feeding on an infected bird and can then spread the potentially lethal strain to animals and humans. Those at greatest risk include seniors and individuals with compromised immune systems.
Symptoms may never materialize, but include fever, headache, nausea, body aches, skin rashes and swollen lymph nodes.
Along with West Nile, mosquitoes are additionally known to transmit chikungunya, dengue, yellow fever and Zika virus.
