Approx. 100 people were reported to have fallen sick with an acute bacterial infection E. Coli after eating contaminated green onions at fast food chain Taco Bell restaurants in US.
The chain immediately dropped the onions at all 5,800 of its North American outlets, and closed dozens of branches along the eastern seaboard.
Government investigators working on similar cases are trying to find out how vegetables apparently infected by animal faeces entered the food chain.
Some are suspecting the spread of infection to methods used in agriculture, and infected manure.