In January of 1999 the state of Massachusetts mandated that all bats found in the living quarters of a house must be tested for rabies. A bite or scratch from a bat maybe so small you might not realize you have been exposed. If you find a bat in your house you should try to confine it to one room and call the Police Department, and they will contact Animal Control to remove the bat and have it tested.
For more information on rabies click here