Rio’s Zika outbreak matches Asian virus, researchers say

The mosquito-borne Zika virus behind last year's outbreak in Rio de Janeiro closely resembles another strain from Asia and may have been introduced by Pacific Island athletes, researchers said Tuesday. The researchers also raised new concerns about the potential for an even worse Zika outbreak during this summer's Olympic Games in Rio, saying many of those studied did not remember being bitten by mosquitoes and that transmission of Zika infection in clusters of people appeared to be commonplace. Zika virus is strongly suspected to be behind a surge in microcephaly, a birth defect in which babies are born with unusually small heads, although a definitive link between microcephaly and Zika has not yet been proven.