First results of Zika-microcephaly study in spring - U.S. official

An Aedes aegypti mosquitoe is seen inside the International Atomic Energy Agency's (IAEA) insect pest control laboratory in Seibersdorf, Austria, February 10, 2016. REUTERS/Leonhard Foeger

BRASILIA (Reuters) - Preliminary results of a U.S.-Brazilian study on the link between the Zika virus that is spreading through the Americas and birth defects will be ready between March and May, a senior U.S. public health official said on Friday. The U.S. government is "very concerned" about a surge of the mosquito-borne virus in Puerto Rico when the weather warms up and "extremely concerned" about the impact Zika can have on Haiti where dengue is endemic, Anne Schuchat, principal deputy director of U.S. Centers for Disease Control and Prevention said after meeting with Brazilian medical researchers. (Reporting by Anthony Boadle; Editing by Frances Kerry)