31.   Much of the contaminated food was found and isolated in state warehouses before it could be shipped, Likens said.

32.   No passengers ate the apparently contaminated food and none became ill, Crawley said.

33.   One possible explanation health officials have sketched out is that one or more victims picked up the bacterium from an isolated serving of contaminated food, Facelle said.

34.   Symptoms of the disease, which is caused by contaminated food or water, include severe fatigue, nausea, vomiting and fever.

35.   That can leave investigators trying to identify contaminated food and trace its source with trails that have often gone cold and memories that are hazy.

36.   The episode also has raised new concerns about food safety and has prompted federal regulators to ask for greater powers to force the recall of contaminated foods.

37.   The link between contaminated food and human illness is clear.

38.   The infection usually is transmitted person to person through fecally contaminated food or drink.

39.   The major thrust of the proposed legislation would be to shift the decision to order a recall to the federal government from the company that is producing contaminated food.

40.   The virus is spread by household or sexual contact with an infected person or by eating contaminated food or by drinking contaminated water.