San Joaquin County health officials enlisted the aid of the Civilian Conservation Corps to remove brush along local streams to reduce mosquito producing stagnant water.
The San Joaquin County Board of Supervisors and residents of the City of Lodi formed the Northern San Joaquin County Mosquito Abatement District in 1945 pictured below. The District uses techniques and materials gleaned from WWII to control mosquitoes capable of spreading malaria.
A second district, the San Joaquin Mosquito Abatement District, was formed for Stockton and the southern portion of the county in 1955. Mosquito-borne St. Louis encephalitis and Western equine encephalomyelitis outbreaks are experienced in California, and there are many human and equine cases in San Joaquin County between 1952 and 1957.
In response to fiscal cutbacks from Proposition 13 in 1978, the governing bodies of the two mosquito abatement districts agreed to consolidate and form the San Joaquin County Mosquito Abatement District in 1980. The consolidated district provided services to all citizens and visitors of the San Joaquin County from a centralized location and staff.
The District expanded its mission in 1993 to include the surveillance and emergency control of other vectors, including ticks and feral bees. To reflect the newly adopted tasks, the District changes its name to "San Joaquin County Mosquito and Vector Control District". Mosquito-borne Western equine encephalitis was detected in adult mosquitoes and sentinel chickens for several years between 1993 and 1996, but fortunately there were no human or equine infections. Mosquito-borne West Nile virus was detected in New York in 1999, and the District anticipated the spread to California in coming years.
West Nile virus was detected in California in 2003. It was first detected in San Joaquin County in 2004 and reached epidemic risk level for most of the years except 2009-2011. (updated 3-2-2022)