U.S. health officials are investigating a salmonella outbreak that has sickened 90 people in several states, with sushi a possible culprit, the Centers for Disease Control (CDC) said on Wednesday.

The outbreak involves salmonella bareilly, an unusual type of salmonella. The strain was reported in 19 states and the District of Columbia from Jan. 28 to April 2, the CDC said in a statement.

The CDC is working with the Food and Drug Administration and state and local health officials to find and interview victims, it said.

No food has been conclusively identified. Many of the ill persons said they had eaten sushi, sashimi or similar foods before becoming sick.

Salmonella infections often cause diarrhea, fever and abdominal cramps and usually lasts four to seven days. Most people recover without treatment, but in rare instances can be fatal.