*Includes confirmed and probable disease cases; **Locally acquired cases reported from Florida and Texas in 2016 and 2017; †Includes cases acquired through other routes (e.g., sexual and laboratory transmission); ††In 2020, all locally acquired cases of Zika in the U.S. territories were diagnosed by antibody testing. Since antibodies against Zika virus can persist for years after infection, serology cannot distinguish between a recent or past infection. Additionally, Zika and dengue virus antibodies cross-react, making it difficult to diagnose which virus is the cause of the current illness. Since 2019, there have been no confirmed Zika virus disease cases reported from U.S. territories.