Salmonella tomato outbreak spreads in the U.S.

According to officials in the U.S. a salmonella outbreak linked to tainted tomatoes has expanded to five more states and the district of Columbia.

The Centers for Disease Control and Prevention (CDC) says the number of states now affected has risen to 28 and the number of people sickened to 277.

Since last week another 49 have become ill and it is reported that at least 43 people have been hospitalized.

The Food and Drug Administration (FDA) says a cluster of nine cases of salmonella poisoning in a single geographic location, may lead to the source of an outbreak - it appears that all of the sickened individuals ate similar tomatoes.

The cluster is possibly nine cases reported by the Chicago Department of Health where the victims ate at two restaurants from the same chain but food safety officials continue to maintain that the outbreak is not linked to a single restaurant or grocery store chain.

Tomatoes from dozens of states and countries whose producers have not been linked to the outbreak have been identified by the FDA and include California, northern Florida and Baja California in Mexico.

The outbreak has been linked by health officials to raw plum, Roma and round tomatoes and consumers are warned to avoid those tomatoes if they come from producers not yet cleared by FDA.

At the time of the initial outbreak the major tomato suppliers were in Mexico and Florida and this has been the main focus of investigators.

According to the CDC the bacterial strain responsible for the current outbreak, Salmonella serotype Saintpaul, is uncommon and last year there were only 25 reported cases of the saintpaul strain with the same genetic fingerprint as that seen in the current outbreak - Mexican officials say Salmonella Saintpaul has never been found in Mexico.

Salmonella bacteria are often the culprit in food-borne illnesses and symptoms include fever, diarrhea, nausea, vomiting and abdominal pain and generally appear within 12 hours to 72 hours of eating tainted food.

Infants, the elderly and those with weakened immune systems are more vulnerable to developing severe illness and salmonella infections usually arise from eating food contaminated by animal feces, but is also caused by contamination from human feces.