West Nile virus has spread across state

West Nile virus has gained a foothold in Massachusetts, with "significant activity" in greater Boston, Worcester, and Springfield, state health officials said today.

No human cases have been reported, but infected mosquitoes and birds have been found across the state, the Massachusetts Department of Public Health said today. The latest mosquitoes testing positive for the virus were found in Boston, Needham, and Reading. Infected birds were found in Fall River, Reading, Saugus, Natick, Worcester, and Chicopee.

"We are finding [West Nile virus] throughout Massachusetts. There is significant activity in the greater Boston area; as well as communities in the Worcester and Springfield areas," state epidemiologist Dr. Al DeMaria said in a statement. "People should consider the virus as being established in Massachusetts for the summer. The warm, wet summer is continuing to support mosquito populations and allowing the virus to spread."

West Nile virus is transmitted to humans through the bite of an infected mosquito. Six people contracted the illness last year in Massachusetts. Most people aren't aware they are infected, but in one of five who are, it can lead to flu-like symptoms. In an even smaller number, about 1 in 150 infected people, the illness is a more serious infection of the brain or spinal cord.

To avoid mosquito bites, health experts recommend staying inside from dusk to dawn or using clothing or insect repellent to cover bare skin when outdoors. Drain standing water outside your home to discourage mosquito breeding, and keep mosquitoes outside with tight screens.