Health authorities are blaming tomatoes for an outbreak of salmonella in nine U.S. states after lab tests have confirmed the link between tomatoes and several cases of salmonellosis (the illness caused by the Salmonella bacteria called Saint Paulthat) in Texas and New Mexico.

“Our preliminary data is showing that the people who became sick in New Mexico and Texas ate raw tomatoes, and that’s their likely source of this illness,” Centers for Disease Control and Prevention’s epidemiologist Casey Barton Behravesh said, as quoted by Reuters.

There have been 57 cases of salmonellosis since late April in the two states. Seventeen people have been hospitalized, but no death has been reported, the CDC said. Moreover, about 30 more people have been sickened in Arizona, Colorado, Idaho, Illinois, Indiana, Kansas and Utah.

The bad news is that no single source, farm, or grocery store has been found to be responsible for the outbreak. Therefore, “the specific type source of tomatoes is under investigation,” Barton Behravesh said.

Until the source of infection is confirmed, the CDC warns consumers in New Mexico and Texas to avoid Roma or red round tomatoes if they want to lower their risk of salmonellosis.

Along the time, not only tomatoes have been blamed to cause salmonellosis. No later than March this year, cantaloupes from Agropecuaria Montelibano, Honduras were blamed for sickening some 50 people across 16 U.S. states including Colorado, New Jersey, new Mexico, Tennessee, Utah, Washington, California, Illinois, Oregon, Oklahoma, New York, and Wisconsin.

Salmonella is a common bacterium that can cause serious and sometimes fatal infections in young children, frail in elderly people and others with weakened immune systems. Symptoms of salmonella include fever, diarrhea, nausea, vomiting and abdominal pain.

Most people recover from salmonella illness without special treatment, but cases of severe diarrhea require medical attention and there’s a risk of infection spreading from the intestines to the bloodstream, a condition that could turn fatal.

There is no vaccine to prevent salmonellosis, but people could prevent the disease by washing their hands before handling food and between handling different food items. Also, cutting boards, counters, knives and other utensils should be washed thoroughly after touching uncooked foods.

Every year, approximately 40,000 cases of salmonellosis are reported in the U.S. Because many milder cases are not diagnosed or reported, the actual number of infections may be thirty or more times greater. Salmonellosis is more common in the summer than winter.