Nearly 100 ill after manure found in Taco Bell onions

The Mexican fast-food chain Taco Bell is at the centre of America's latest food scare, after nearly 100 people were reported to have fallen sick with an acute bacterial infection after eating contaminated green onions at Taco Bell restaurants.

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.

Another outbreak involves the E.coli O157:H7 bacteria, a singularly nasty E.coli strain that originates in the stomachs of grain- and corn-fed cattle. In September, three people died and 200 others fell ill after eating bagged spinach from a Californian grower. There have been problems, too, with salmonella, including one outbreak in tomatoes which affected dozens of people across 21 states.

Michael Pollan, a journalism professor who has written extensively about food safety, said all the recent problems stemmed from the intensive, industrial-style agriculture increasingly practised in the United States.

The 0157:H7 strain of E.coli was unknown until cattle were taken from their traditional grazing grounds, pushed into industrial feedlots and fed grain and corn instead.

Faeces from those animals, in turn, can sometimes enter the water supply on big farms and find its way into irrigation canals in vegetable fields.

Professor Pollan recently likened many US farms to giant "petri dishes" in which all sorts of bacterial cultures could grow and thrive. Fast-food chains have taken steps to safeguard their ground beef - which can easily get mixed with faeces - but vegetables represent a new front in the fight for public health.

Federal investigators responding to the Taco Bell outbreak also checked the safety of other ingredients. Now the lawsuits are flying. On Long Island, outside New York, the family of an 11-year-old boy who fell ill filed a negligence suit against the chain. The boy ate three tacos last month and had to be treated in hospital. He recovered.