Followers of Bhagwan Shree Rajneesh (pictured) began deliberately infecting people in The Dalles, Oregon, with Salmonella in the first and largest bioterrorist attack in United States history.

Rajneesh, also known as Acharya Rajneesh, Bhagwan Shree Rajneesh, and later as Osho, was an Indian godman, philosopher, mystic and founder of the Rajneesh movement. He was viewed as a controversial new religious movement leader during his life. He rejected institutional religions, insisting that spiritual experience could not be organized into any one system of religious dogma. As a guru, he advocated meditation and taught a unique form called dynamic meditation. Rejecting traditional ascetic practices, he advocated that his followers live fully in the world but without attachment to it.

In 1984, 751 people suffered food poisoning in The Dalles, Oregon, United States, due to the deliberate contamination of salad bars at ten local restaurants with Salmonella. A group of prominent followers of Rajneesh led by Ma Anand Sheela had hoped to incapacitate the voting population of the city so that their own candidates would win the 1984 Wasco County elections. The incident was the first and largest bioterrorist attack in U.S. history.

The Dalles formally the City of the Dalles and also called Dalles City, is an inland port, the county seat of and the largest city in Wasco County, Oregon, United States. The population was 16,010 at the 2020 census, and it is the largest city in Oregon along the Columbia River outside the Portland Metropolitan Area. The Dalles is 75 miles (121 km) east of Portland, within the Columbia River Gorge National Scenic Area.

Salmonella is a genus of rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of Salmonella are Salmonella enterica and Salmonella bongori. S. enterica is the type species and is further divided into six subspecies that include over 2,650 serotypes. Salmonella was named after Daniel Elmer Salmon (1850–1914), an American veterinary surgeon.