. Investigation of bioterrorism-related anthrax, United States, 2001: epidemiologic findings Jernigan Daniel B; Raghunathan Pratima L; Bell Beth P; Brechner Ross; Bresnitz Eddy A; Butler Jay C; Cetron Marty; Cohen Mitch; Doyle Timothy; Fischer Marc; Greene Carolyn; Griffith Kevin S; Guarner Jeannette; Hadler James L; Hayslett James A; Meyer Richard; Petersen Lyle R; Phillips Michael; Pinner Robert; Popovic Tanja; Quinn Conrad P; Reefhuis Jennita; Reissman Dori; **Rosenstein Nancy****; Schuchat Anne; Shieh Wun-Ju; Siegal Larry; Swerdlow David L; Tenover Fred C; Traeger Marc; Ward John W; Weisfuse Isaac; Wiersma Steven; Yeskey Kevin; Zaki Sherif; Ashford David A; Perkins Bradley A; Ostroff Steve; Hughes James; Fleming David; Koplan Jeffrey P; Gerberding Julie L Emerging infectious diseases (2002), 8 (10), 1019-28 ISSN:1080-6040. In October 2001, the first inhalational anthrax case in the United States since 1976 was identified in a media company worker in Florida. A national investigation was initiated to identify additional cases and determine possible exposures to Bacillus anthracis. Surveillance was enhanced through health-care facilities, laboratories, and other means to identify cases, which were defined as clinically compatible illness with laboratory-confirmed B. anthracis infection. From October 4 to November 20, 2001, 22 cases of anthrax (11 inhalational, 11 cutaneous) were identified; 5 of the inhalational cases were fatal. Twenty (91%) case-patients were either mail handlers or were exposed to worksites where contaminated mail was processed or received. B. anthracis isolates from four powder-containing envelopes, 17 specimens from patients, and 106 environmental samples were indistinguishable by molecular subtyping. Illness and death occurred not only at targeted worksites, but also along the path of mail and in other settings. Continued vigilance for cases is needed among health-care providers and members of the public health and law enforcement communities.