Malaria is still a big killer in developing countries. In 2016, the disease claimed 455,000 lives and caused 216 million cases. A new drug has been approved that provides a potent, new weapon against malaria: it can wipe out the parasite from a person’s body with a single dose. There’s still a challenge to overcome: the drug requires a high-tech blood test that cannot be easily administered in the rural areas where the disease thrives.