LONDON (AP) — Scientists have found evidence of a drug-resistant form of malaria in Africa. Researchers detected genetic mutations in nearly 20% of blood samples in Uganda by 2019. That suggests the main drug used against malaria is losing effectiveness there. Experts worry there could be drug-resistant malaria elsewhere in Africa and say doctors should consider treatment changes to stop its spread. Resistant forms of malaria were previously detected in Asia, but Africa accounts for more than 90% of the world’s malaria cases. The disease is caused by a parasite that is spread through mosquito bites. The research was published Wednesday in the New England Journal of Medicine.