Showing Tinker's Plague by Stephen B. Pearl

Oil reserves depleted. Society collapsed.
A few places cling to modern technology. For everywhere else, there are the Tinkers.

In southern Ontario, Novo Gaia uses sustainable energy to support its citizens in comfort. From there, Novo Gaia sends Doctors of Applied General Technology, tinkers, into the Dark Lands to install everything from solar stills to televisions—and make a profit.

Brad Cooper is a tinker on his route in Guelph when he finds himself at the epicentre of a plague outbreak. Stranded without support in a tenuously-held quarantine zone, he must use his limited medical training in a desperate search for a treatment against an insidious relic from an age of excess.

Meanwhile, fuelled by panic, other townspeople caught within the quarantine zone conspire to sabotage relief efforts. Distrusted by the people he's trying to help, hampered by political rivals, under-supplied, over-worked, and with his own risk of infection increasing, Brad seems to be fighting a losing battle as the casualties mount...