West Nile virus activity is on the rise in some northern California counties, according to the Sacramento-Yolo Mosquito and Vector Control District. Three dead birds and 13 mosquito samples tested positive for the virus on Aug. 13, “the highest number of positive results reported in a single day this year,” the agency said in a news release.

Spraying for West Nile virus-infected mosquitoes is planned for central Fort Collins. On Aug. 17, the spraying of a fine mist of permethrin-based product will occur within the following boundaries: From Shields Street on the west to Lemay Avenue on the east, between Mulberry Street on the north to Harmony Road on the south.

Health experts say a confirmed case of West Nile Virus is connected to someone who travelled outside of Manitoba, but that doesn't mean there won't be homegrown cases this summer.

Philadelphia Health Department plans to spray for mosquitoes in West Philadelphia to reduce West Nile virus risk.