The 2001 anthrax attacks , also known as Amerithrax from its Federal Bureau of Investigation ( FBI ) case name , occurred within the United States over the course of several weeks beginning on September 18 , 2001 , one week after the September 11 attacks . Letters containing anthrax spores were mailed to several news media offices and two Democratic U.S. Senators , killing five people and infecting 17 others . According to the FBI , the ensuing investigation became " one of the largest and most complex in the history of law enforcement . " The anthrax attacks , as well as the September 11 , 2001 attacks , spurred significant increases in U.S. government funding for biological warfare research and preparedness . For example , biowarfare-related funding at the National Institute of Allergy and Infectious Diseases ( NIAID ) increased by $ 1.5 billion in 2003 . In 2004 , Congress passed the Project Bioshield Act , which provides $ 5.6 billion over ten years for the purchase of new vaccines and drugs
September 11 attacks
September 11 attacks
First Responder Anthrax Preparedness Act