The Massachusetts Department of Public Health has found West Nile virus in mosquito samples gathered in Rochester.

In a press release Friday, Health District Director Karen Walega said that a mosquito tested positive for the virus, which can infect people of all ages, but is a higher risk for those 50 and older.

Last week, Walega warned that now is the peak season for mosquito activity. Earlier this summer, the virus was found in Mattapoisett. Walega, who is the health agent for Rochester and Marion, said there are no confirmed cases in Marion. But she cautioned that the virus is most likely widespread.

“We have to assume it’s everywhere. We just haven’t gotten the call from state officials yet,” she said. “We need to take precautions. Everybody should use mosquito repellent and follow our recommendations to protect people and their loved ones from getting mosquito bites.”

Next week, the Plymouth County Mosquito Control Board will spray the town to knock down the mosquito population. The board generally sprays late at night, beginning around 2 a.m.

The health district recommends staying indoors from dusk to dawn during peak mosquito hours. If you are outdoors and notice mosquitoes, cover up or wear repellent with the ingredient DEET. Wearing long sleeve shirts and pants will keep mosquitoes away from skin.

Around the home, drain standing water, which is where mosquitoes breed. Install or repair screens to keep the insects out of homes.

For more information, call the Marion Rochester Regional Health District 508-763-5421.