Rapid and simple assays to detect infectious agents are key to tracking emerging epidemics. Chotiwan et al. describe a loop-mediated amplification (LAMP) assay that detects Zika virus RNA in human biofluids such as serum and semen, as well as in mosquitoes, the insect vector that transmits the disease. The assay successfully distinguished the Asian-lineage Zika virus, which is associated with the current outbreak in the Americas, from the African-lineage Zika virus. This approach should enable tracking of the Asian-lineage strain as it moves into new geographical locations.