FILE - In this Oct. 8, 2013, file photo, a sign marks the entrance to the federal Centers for Disease Control and Prevention,in Atlanta. Citing an anthrax scare and a recurring problem with safety, the Centers for Disease Control and Prevention on Friday, July 11, 2014, shut down two research labs and stopped shipping highly dangerous germs to other labs. One of the closed facilities was involved an incident last month that could have accidentally exposed workers in three labs to anthrax. A second, previously undisclosed problem earlier this year involved deadly bird flu. (AP Photo/David Goldman, File)

FILE - In this Oct. 8, 2013, file photo, a sign marks the entrance to the federal Centers for Disease Control and Prevention,in Atlanta. Citing an anthrax scare and a recurring problem with safety, the Centers for Disease Control and Prevention on Friday, July 11, 2014, shut down two research labs and stopped shipping highly dangerous germs to other labs. One of the closed facilities was involved an incident last month that could have accidentally exposed workers in three labs to anthrax. A second, previously undisclosed problem earlier this year involved deadly bird flu. (AP Photo/David Goldman, File)