"The source of contamination has been ongoing at least through early June. And we don't have any evidence that whatever the source is, it's been removed from the market," said Dr. Patricia Griffin of the Centers for Disease Control and Prevention.

A number of 810 people in 36 states and the District of Columbia have gotten sick after eating tomatoes, but no death has been blamed on the outbreak. It all started in mid-April; over 95 people have been hospitalized.

"We have also kept an open mind about other possibilities and are looking into other ingredients," Griffin added.

Since April, 810 persons infected with Salmonella Saintpaul with the same genetic fingerprint have been identified in 36 states and the District of Columbia. These were identified because clinical laboratories in all states send Salmonella strains from ill persons to their State public health laboratory for characterization. Maine and Minnesota have been added to the list of states with ill persons.

The number of ill persons identified in each state is as follows: Arkansas (10 persons), Arizona (39), California (10), Colorado (8), Connecticut (4), Florida (1), Georgia (18), Idaho (3), Illinois (78), Indiana (11), Kansas (14), Kentucky (1), Maine (1), Maryland (25), Massachusetts (18), Michigan (4), Minnesota (2), Missouri (12), New Hampshire (3), Nevada (4), New Jersey (4), New Mexico (85), New York (25), North Carolina (5), Ohio (6), Oklahoma (19), Oregon (7), Pennsylvania (6), Rhode Island (3), Tennessee (6), Texas (342), Utah (2), Virginia (22), Vermont (1), Washington (4), Wisconsin (6), and the District of Columbia (1).

Among the 523 persons with information available, illnesses began between April 10 and June 15, 2008. Patients range in age from <1 to 99 years; 51% are female. At least 95 persons were hospitalized. No deaths have been officially attributed to this outbreak. However, a man in his sixties who died in Texas from cancer, had an infection with the outbreak strain of Salmonella Saintpaul at the time of his death. The infection may have contributed to his death.

Salmonella is a bacterium that causes one of the most common eteric (intestinal) infections in the United States. The bacterium that has gotten sick such a large part of the population is called Salmonella Saintpaul and CDC officials said that this kind of bacterium is very rare.

The investigations are very difficult because people eat different types of products combined together. In spite of the fact that the tomato tests came out negative, many salesmen complained because the demand and the market price are going down and sales could be affected for many years now.

The investigators will continue the tests, by collecting water and other environmental samples, in order to discover the real cause of the illness.

FDA is looking after other ingredients besides tomatoes. Dr. David Acheson, associate commissioner for foods at the Food and Drug Administration, said that even there is a strong epidemiological association with tomatoes, the agency is considering other ingredients as the source of the outbreak.

Dr. David Acheson said that FDA has collected about 1,700 tomato samples, but  all of these have been negative. He also warned that despite the agency’s efforts, the investigators may never find the source of the outbreak.