According to the county Mosquito and Vector Control District, similar mosquito-fogging efforts took place on July 21 this year.
However, despite that effort, county officials report that mosquitoes have since tested positive for the virus. West Nile Virus can also be found in dead birds, squirrels and other small animals.
In an effort to prevent any human cases, mosquito fogging is scheduled to take place beginning at 9 p.m. and concluding by 5 a.m. Tuesday.
The area to be treated is roughly bordered by Peninsula and Second avenues in San Mateo, and North Idaho Street and Severn Lane in Hillsborough.
In order to mitigate personal risk of infected mosquito bites, the vector control district recommends eliminating all sources of standing water on personal property, and wearing bug repellent containing the chemical DEET.