The Romans called malaria the "rage of the Dog Star," since its fever and chills so often arrived during the caniculares dies, the dog days of summer, when Sirius disappeared in the glow of the sun. To avoid it, ancient Romans built their grand villas high in the hills, fled the mosquito-ridden wetlands that encircled Rome, and prayed for relief at temples dedicated to the fever goddess, Febris.

It was the emperor Caracalla's physician, Serenus Sammonicus, who in the second century came up with Rome's first antimalaria...