Would you let a scientist implant a parasite in your brain to treat an illness? The idea of using a parasite as a medical tool might seem outlandish, but it also offers hope for conditions like Parkinsons and Alzheimer’s. Researchers have speculated that if a parasite could deliver drugs directly to the brain, it might help doctors treat these conditions.

An international team of scientists is doing just that. They are using a single-celled parasite known as Toxoplasma gondii, which causes an infection called toxoplasmosis. The parasite naturally travels from the human gut to the central nervous system and delivers proteins to host cells. In the experiment, bioengineers hacked systems within the T. gondii’s cells that produce and release proteins outside the cell, called secretion systems.

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