Bats pose an infectious disease paradox: they often harbor a multitude of viruses capable of killing other mammals, including humans, but the viruses rarely sicken or kill bats. The question is why.
Previous studies indicate that bats got an evolutionary immune system boost to protect them from DNA damage that resulted from the high metabolic rates they needed to fly. In turn, high metabolic rates resulted in elevated body temperatures that reach fever range. That combination may have given them a special ability to fight viral infections, researchers in the United States, Australia, and the United Kingdom have theorized.
Why Do Viruses in Bats Rarely Make Them Sick?. JAMA. 2014;311(24):2474. doi:10.1001/jama.2014.6700