BOSTON -- Mosquitoes in Brighton and Boston's Back Bay have tested positive for the West Nile virus, the Boston Public Health Commission said Friday.

Mosquitoes infected with the disease were previously found in Hyde Park, Dorchester, Jamaica Plain, West Roxbury and the Boston Harbor Islands. Last month, a red-tailed hawk in Jamaica Plain and a blue jay in Charlestown tested positive for West Nile virus.

There have been no confirmed human cases in Boston.

"It's that time of year when it's not unexpected to find mosquitoes infected with the West Nile virus in the Boston area," said Dr. Anita Barry, director of the Communicable Disease Control Division at the Boston Public Health Commission.

The city has been putting larvicide in catch basins designed to reduce the number of mosquitoes, Barry said. She said West Nile virus poses very low risk to humans, but even that low risk can be reduced if people take a few simple steps to protect themselves and their families.

"My advice is always the same: Avoid mosquito bites, wear long pants, long sleeves, use insect repellant, preferably one containing DEET, and, if possible, avoid activities from dusk to dawn when mosquitoes may be biting most heavily," she said. "It's also a good idea to make sure window and door screens are in good repair to prevent mosquitoes from getting inside your house."

To prevent mosquitoes from breeding, she advised turning over unused flower pots, buckets, wheelbarrows and garbage cans; removing leaves and other debris that can clog gutters and trap water; disposing of or covering old tires; and covering swimming pools and kiddie pools when not in use.