The Eastern equine encephalitis threat level was raised to high Thursday in four Massachusetts communities and to moderate in six others after detection of infected mammal-biting mosquitoes in the area, officials said. The EEE threat is high in Easton, Raynham, Taunton, and West Bridgewater. Residents in high-risk areas are urged to avoid evening outdoor events for the remainder of the mosquito season, said a statement from the Massachusetts Department of Public Health. Communities with a moderate risk of EEE are Norton, Mansfield, Dighton, Berkley, Sharon, and Stoughton, the statement said. There has been one human case of EEE this year: A Norfolk County woman in her 80s died earlier this month.