Eastern equine encephalitis, a mosquito-borne virus, has instilled concern as states along the East and Gulf Coasts grapple with the potential for larger outbreaks — and with next steps. As of Sept. 10, a total of four EEE cases have been reported in Massachusetts, according to the Centers for Disease Control and Prevention.

This decrease in risk comes as winter brings an end to mosquito season. This year, Massachusetts has seen 12 cases of EEE in humans, of which four patients died.