Vector Control officials are planning mosquito spraying in parts of South San Jose and unincorporated Santa Clara County later this week, after a group of West Nile virus-positive mosquitoes were found. The County of Santa Clara Vector Control District announced Tuesday that mosquitoes with the virus were found in zip codes 95111, 95112, 95128 and 95136. In response, the district will conduct spraying in an area centered at Monterey and Umbarger roads starting at 10 p.

m. Thursday night, weather permitting. Spraying is expected to take two to four hours.

According to a map provided by the district , the spraying area roughly bordered by San Jose Avenue and Phelan Avenue to the north, Senter Road to the east, Hillsdale Avenue, Snell Avenue and Senter Road to the south, and Highway 87, the Guadalupe River and Almaden Road to the west. Officials said residents do not need to relocate during treatment. Pesticides are applied at an "ultra-low volume", are approved by the EPA for use in public areas and used by vector control agencies throughout the state.

Earlier this month, officials conducted spraying in parts of North San Jose and Milpitas , after two West Nile-positive mosquitoes were found. Tuesday's announcement comes days after county health officials announced the first two cases of the virus this year . According to the health department, one of the patients was an immunocompromised adult and died at a hospital after experiencing West Nile symptoms.

The second patient, als.