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.

Idaho health officials encourage people to take steps to prevent mosquito bites while outdoors and on their properties.

This is the second human case reported in Indiana this summer, with the first reported in July 2025 in Vanderburgh County in southern Indiana.

A dead bird was found in Calhoun County and tested positive for West Nile Virus at the Michigan Department of Health and Human Services Bureau of Laboratories. This is the first confirmed animal case of the virus in Calhoun County for 2025, according a Calhoun County Public Health Department statement Friday, Aug. 15.

West Nile virus, Covid, hand foot and mouth disease cases rising in New York — and tragedy at the CDC. Here's the latest public health updates from Your Local Epidemiologist New York.

The risk for West Nile virus is high in 10 cities and towns in Massachusetts, including Boston, public health officials say.

How bad is the West Nile infection rate? The vector index, which is the rate of mosquitoes infected with West Nile virus, is 1.19 in the planned spraying area, according to an Aug

Officials of the Boston Public Health Commission (BPHC) are urging residents to take precautions as the risk level of transmission of the West Nile Virus in Boston has been raised to ‘high’.