Malaria is the deadliest pathogen in human history. Nearly half the people on Earth are at risk of contracting the disease from the parasites that cause it. But humans aren't the only ones who can get these parasites—different forms are found in other animals, including birds. By studying the DNA of those strains, scientists can get a better picture of how malarial parasites live, which may give clues on how to stop the disease. In a new paper in PNAS, researchers analyzed blood samples of more than 1,000 species of birds from the Andes looking for malaria; they found that the strains of malaria present in a local area don't always neatly align with the types of birds living there.