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 quick-fix, one that later became literally synonymous with magical solutions everywhere. An amulet should be worn, Sammonicus advised, inscribed with a powerful incantation: "Abracadabra."

It didn't work, needless to say. Thanks to deforestation and flooding that extended mosquito habitat, malaria worsened near the end of the Roman empire, contributing to its decline. It took a lot more than Abracadabras for the malaria parasite, Plasmodium, to unclench its tentacles: a state-run quinine distribution program in the early 1900s, the ruthless swampland reclamation programs of Mussolini a few decades later, a blitz of DDT around midcentury, and the general economic transformation of the lot of the Italian peasant all had to run their long and arduous course before malaria departed from Italy, centuries after Rome fell.

Yet the spirit of Sammonicus's cure for malaria still beckons. You'd think a pathogen as wily as Plasmodium would command a bit more respect. The malaria parasite has been responsible for half of all human deaths since the Stone Age, and one in 14 of us alive today still carry genes that first arose to help protect us from its ravages. Malaria has shaped our trade and settlement patterns, and our demographics. Today, it sickens 300 million every year, and kills nearly 1 million, despite the fact that we've known how to cure it (with parasite-killing drugs) and prevent it (by avoiding mosquito bites) for over a century. And even as the fight against malaria gains momentum, research reveals that malaria's tentacles continue to dig ever deeper.

Part of malaria's wicked genius is that since ancient times, it has fooled us into thinking it is a trivial problem, easily solved. Diseases such as yellow fever, or plague, or polio, have always filled us with dread. But not malaria. Almost all of our attempts to squelch it, from thousands of years ago to today, have treated the disease as a weak foe, allowing malaria to flourish, nearly unchecked, to this day.