Badge of Infamy by Lester Del ReyGutenberg link
Daniel Feldman was a doctor once. He made the mistake of saving a friend’s life in violation of Medical Lobby rules. Now, he’s a pariah, shunned by all, forbidden to touch another patient. But things are more loose on Mars. There, Doc Feldman is welcomed by the colonists, even as he’s hunted by the authorities. But, when he discovers a Martian plague may soon wipe out humanity on two planets, Feldman finds himself a pivotal figure. War erupts. Earth is poised to wipe out the Mars colony utterly. A cure to the plague is the price of peace, and only Feldman can find it (summary by Steven H. Wilson).
A nice, fast-SF story - easy reading, and worked well in Plucker format. Reminiscent of Heinlein's "Red Planet" - both tell the tale of an opressed Mars throwing off the shackles of the mother planet, and both involve characters on the run across a cold (but endurable) Mars. I might give the audio version a listen sometime..