Jason Howland: The most dangerous threat of rabies in the U.S. is flying overhead.

Gregory Poland, M.D., Vaccine Research Group Mayo Clinic: "It used to be thought, well, it's a rabid dog. But the more common way of getting rabies is from the silver-haired bat."

Jason Howland: The deadly virus is transmitted from the saliva of infected animals to humans, usually through a bite.

Dr. Poland: "… The bat doesn't always bite. Sometimes the saliva will drool onto you, and you could have a minor open cut. Or sometimes a bat will lick on the skin and, again, transmit the virus that way."

Jason Howland: Dr. Poland says that's why if you wake up and find a bat in the room, you should get the rabies vaccine.

Dr. Poland: "People think, 'Well, the bat's in the house. We woke up with it, doesn't look like it bit anybody.' Doesn't matter. Rabies is such a severe disease with no cure, no treatment for it, that the safer thing to do is to give rabies vaccine."

Jason Howland: That includes an immune globulin and multidose rabies series which is not cheap. A typical series of rabies vaccines cost anywhere from three to seven thousand dollars.

For the Mayo Clinic News Network, I'm Jason Howland.