CDC issued an alert after identification of locally acquired malaria cases (P. vivax) in two U.S. states (Florida [4] and Texas [1]) within the last 2 months. Locally acquired mosquito-borne malaria has not occurred in the United States since 2003 when eight cases of locally acquired P. vivax malaria were identified in Palm Beach County, FL (1). Mosquito surveillance and control measures have been implemented in the affected area.