Salmonella food poisoning first linked to uncooked tomatoes has spread to 16 U.S. states, health officials said Saturday.

Investigations by the Texas and New Mexico departments of health and the U.S. Indian Health Service have tied 56 cases in Texas and 55 in New Mexico to raw, uncooked, tomatoes.

"We're seeing a steady increase," Deborah Busemeyer, New Mexico Department of Health communications director, said Saturday.

An additional 50 people have been sickened by the same Salmonella Saintpaul infection in Arizona, California, Colorado, Connecticut, Idaho, Illinois, Indiana, Kansas, Oklahoma, Oregon, Utah, Virginia, Washington and Wisconsin, the U.S. Centers for Disease Control and Prevention reported.

Investigators are trying to determine if raw tomatoes also are responsible for the illnesses in those states, said Arleen Porcell, a CDC spokeswoman.

The source of the tomatoes responsible for the illnesses has not been pinpointed, but health officials in Texas and New Mexico said none of them was grown in those two states. At least 23 people have been taken to hospital but no deaths have been reported, she said. Patients ranged in age from one to 82.

The rarity of the Saintpaul strain and the number of illnesses "suggest that implicated tomatoes are distributed throughout the country," she said. The illnesses began between April 16 and May 27, Porcell said.

Cherry tomatoes, grape tomatoes, tomatoes sold with the vine still attached and homegrown tomatoes are likely not the source of the outbreak, Busemeyer said. Also not associated with the outbreak are raw Roma, red plum and round red tomatoes from Canada, Arkansas, California, Georgia, North Carolina, South Carolina, Tennessee, Texas, Belgium, the Dominican Republic, Guatemala, Israel, Netherlands and Puerto Rico, said the U.S. Food and Drug Association.

However, CTV News reported on its website that McDonald's fast-food outlets in Canada have temporarily removed tomatoes from their menu options, after the U.S. warnings. McDonald's said it hasn't experienced any problems to date but considers the move a "precautionary measure."

Salmonella is a bacteria that lives in the intestinal tracts of humans and other animals. It usually is transmitted to humans by eating food contaminated with animal feces.

Most infected people suffer fever, diarrhea and abdominal cramps starting 12 to 72 hours after infection. The illness tends to last four to seven days. Many people recover without treatment but severe infection and death is possible.

With files from the Canadian Press