Things aren't as bad as they seem, it is just that there was a bat flying around the stadium and even landed on a person.
The person brushed it away but the bat was never captured or tested.
So the Maryland Department of Health and Mental Hygiene said:
"The Bats are an important part of our environment; however, they can sometimes be infected with rabies. Rabies is a viral disease of mammals that can be transmitted by infectious saliva, usually through a bite."
So now they're saying anyone that was at that game and came into contact with the bat should contact their local health department.
Rabies is treatable if caught early, but if undiagnosed can become fatal very quickly.
So were you at the game? Did a bat land on you? Then go get tested!