Taken together, longitudinal clinical and molecular data described above from Tanzania, East Africa, extending from pre-ACT implementation, (before 2006), to a decade of wide scale artemether-lumefantrine use in Bagamoyo district, provide evidence for declining susceptibility to ACT, both to artemether and lumefantrine, among the P. falciparum population. These parasites ("last man standing") that survived 10 years of ACT exposure have indeed shown excellent survival instincts and may thus be particularly resistant prone. However, if P. falciparum resistance to ACT develops in Africa, this will have devastating effects on malaria morbidity and mortality and may swiftly ruin the improvements the global malaria community achieved during the past decade with ACT as a key component for success.