HOUSTON -- Health officials are investigating a multistate outbreak of salmonella in tomatoes, KPRC Local 2 reported Tuesday.

Texas Department of State Health Services officials said 21 cases of the Saintpaul strain of salmonella have been reported in Texas since mid-April, including cases in Harris, Fort Bend, Dallas, Tarrant, Hays and Cameron counties.

New Mexico health officials have reported that 31 people in seven counties have also been infected with the same strain of salmonella since May 6.

According to the Centers for Disease Control and Prevention, cases have also been reported in Arizona, Colorado, Idaho, Illinois, Indiana, Kansas and Utah since April 23.

The consumption of raw Roma and red, round tomatoes has been implicated as the likely source of infections, officials said. The investigation is in its early stages and the specific types and source of tomatoes have not been determined.

Health officials suggested that infants, the elderly and people with impaired immune systems not eat any raw Roma or full-sized round tomatoes other than those sold attached to the vine or grown at home.

More than a dozen people have been hospitalized, according to the Centers for Disease Control and Prevention. No deaths have been reported.

News of the outbreak concerned some Houston-area shoppers. But one woman had some advice for everyone.

"Just wash your stuff -- anything you get. You wash your fruit, grapes and all that. Wash it, you'll be OK," shopper Gladys Jones said.

But health officials said simply washing them may not be enough, especially if the salmonella is inside the tomatoes.

"You should purchase tomatoes that still have the stem on them," said Kathy Barton with the Department of Health and Human Services.

Consumers were also advised to:

cook tomatoes to 145 degrees for at least 15 seconds to kill Salmonella
avoid buying bruised or damaged tomatoes
throw away tomatoes that appear to be spoiled
thoroughly wash all tomatoes under running water
refrigerate cut, peeled or cooked tomatoes within two hours or throw them away
separate tomatoes that will be eaten raw from any raw meat, poultry, seafood or vegetables
wash cutting boards, dishes, utensils and countertops with hot water and soap in between handling of different foods
wash hands thoroughly

Symptoms of salmonella infection include:

headache
stomach pain
diarrhea
nausea
vomiting

Illness from salmonella normally lasts four to seven days and most people generally recover without treatment. People with symptoms are advised to drink plenty of water, get extra rest and visit a doctor as soon as possible. When severe infection occurs, salmonella may spread from the intestines to the bloodstream and then to other body sites and can cause death.

More Information:

CDC: Salmonella Saintpaul Outbreak Investigation
CDC: Salmonella Frequently Asked Questions
CDC: Map of States Reporting Salmonella Saintpaul
Information About New Mexico Salmonella Cases
FDA: Safe Handling of Raw Produce, Fresh-Squeezed Juices