Parasites take an enormous toll on human and veterinary health. But researchers may have found a way for patients with brain disorders and a common brain parasite to become frenemies. A new study published in Nature Microbiology has pioneered the use of a single-celled parasite, Toxoplasma gondii, to inject therapeutic proteins into brain cells. The brain is very picky about what it lets in, including many drugs, which limits treatment options for neurological conditions. As a professor of microbiology, I’ve dedicated my career to finding ways to kill dangerous parasites such as Toxoplasma. I’…