The U.S. Centers for Disease Control (CDC) explains on its website that there are many causes of microcephaly. And the World Health Organization (WHO) said in a statement that the cause of the microcephaly outbreak in Brazil had yet to be determined. However, the CDC says the link between a virus infection and microcephaly is being investigated._________________________美国疾控中心在网站上给出的解释是:引起小头畸形症的原因很多.世界卫生组织发表的声明表示,巴西小头畸形症爆发的原因尚未确定. 然而,美国疾控中心表示正在调查一种病毒感染和小头畸形症之间的关系.________________________
