Table 3. Epidemic Intelligence Service investigations in which bioterrorism or intentional contamination was considered a cause.

Report No.	Outbreak	Conclusion
84-093	Salmonellosis, Oregon, 1984	A total of 751 persons became ill with salmonella gastroenteritis. Religious group deliberately contaminated salad bars. Salmonella enterica Typhimurium strain found in laboratory at commune was indistinguishable from outbreak strain (5).
97-008	Shigella dysenteriae type 2, Texas, 1996	Diarrheal illness in hospital laboratory workers who ate pastries, anonymously placed in break room. Identical strains of S. dysenteriae type 2 were isolated from stool cultures of case patients, from recovered muffin, and from laboratory stock culture, part of which was missing.
98-006	S. sonnei, New Hampshire, 1997	Seven laboratory workers at local hospital became ill with gastroenteritis. Most cases caused by strain of S. sonnei that was highly related to a stock culture strain maintained by the hospital laboratory. Possibility that first two cases were caused by intentional contamination could not be excluded.
99-025	Anthrax hoaxes, 1998	Centers for Disease Control and Prevention received reports of alleged anthrax exposure; letters were sent to health clinics in Indiana, Kentucky, and Tennessee and to private business in Tennessee; three telephone threats of anthrax contamination of ventilation systems were made to public and private buildings; all threats were hoaxes.
99-059	Unexplained critical illness, New Hampshire, 1999	A 38-year-old woman was admitted to a hospital with fever, myalgia, and weakness; severe illness and death occurred 32 days after hospital admission; serum specimens indicated Brucella species. Patient’s history of multiple febrile illnesses suggested unspecified autoimmune process.
99-94-1	Encephalitis cluster, New York City, 1999	Several residents were hospitalized with illness of unknown etiology characterized by fever, encephalitis, axonal neuropathy, and flaccid paralysis (unpublished data: Epi-1 report); increase in deaths of New York City birds, especially crows; human and bird tissue samples were positive for West Nile-like virus.