How some trypanosomes cause sleeping sickness while others don't

Trypanosome parasites transmitted by tsetse flies cause devastating diseases in humans and livestock. Different subspecies infect different hosts: Trypanosoma brucei brucei infects cattle but is non-infectious to humans, whereas T. b. gambiense and T. b. rhodesiense cause sleeping sickness in humans. A new study reveals how humans can fight off some trypanosomes but not others.