Washington, April 27 - The U.S. Food and Drug Administration and the Centers for Disease Control and Prevention told people on Sunday not to eat raw alfalfa sprouts, saying they may be contaminated with salmonella.
The contamination appears to be in seeds so washing the sprouts may not help, the FDA said in a statement.
"Other types of sprouts have not been implicated at this time," the agency said.
"FDA will work with the alfalfa sprout industry to help identify which seeds and alfalfa sprouts are not connected with this contamination, so that this advisory can be changed as quickly as possible."
The FDA said 31 Salmonella Saintpaul infections have been seen in Michigan, Minnesota, Pennsylvania, South Dakota, Utah, and West Virginia.
"Some reported eating raw sprouts at restaurants; others reported purchasing the raw sprouts at the retail level," the FDA said.
"This outbreak appears to be an extension of an earlier outbreak in 2009. In February and March, an outbreak of Salmonella Saintpaul infections occurred in Nebraska, South Dakota, Iowa, Kansas, and Minnesota," the FDA added.
The FDA has been struggling with several high-profile outbreaks of food poisoning, including salmonella linked to peanut products. Congress is discussing the possibility of setting up a new food safety agency with more resources than the FDA has.