Theileria drug resistance is spreading because bovine theileriosis treatment leans on a single drug, buparvaquone. A drug-repurposing screen of the Global Health Priority Box found that rotenone kills Theileria annulata infected cells, keeps working against buparvaquone-resistant cells, and collapses their mitochondrial energy supply. That makes mitochondrial bioenergetics a resistance-independent target for next-generation antiparasitic drugs. Why theileria drug resistance has become a livestock problem Bovine theileriosis is a severe tick-borne disease, and Theileria annulata is the parasite behind it across tropical and subtropical regions. Herds pay for the infection in mortality, reduced milk yield, lost productivity and reproductive impairment. Commercial operations feel it most, because they have no second drug class…