Even if federal officials have yet to establish the cause of a salmonella outbreak that has affected almost 400 people in 42 states, state officials in Minnesota revealed yesterday that they believe peanut butter may be involved.

The Minnesota Department of Health said yesterday that preliminary testing found salmonella bacteria in a 5-pound container of King Nut brand creamy peanut butter.

The tests have not linked it to the type of salmonella involved in the national outbreak, but some additional results are still expected. This product is not sold in grocery stores, or so it appears, but it's distributed in Minnesota to long-term care centers, hospitals, schools, universities, restaurants, cafeterias and bakeries.

DNA fingerprint tests that could confirm whether the salmonella found in the peanut butter is the same strain that has caused illnesses across the United States won't be finished until Monday or Tuesday, but the epidemiological evidence is really strong.

Minnesota is working with the national Centers for Disease Control and Prevention (CDC) in order to track the outbreak, which first began in mid-October. According to the CDC, California has the largest number of cases, 55, followed by Ohio, 53, and Massachusetts, with 39. Minnesota has 30 cases, ten of them being found in nursing homes and most of the other 20 in schools or hospitals.

Salmonella can cause diarrhea, fever and abdominal cramps, generally lasting from four to seven days. Even if most people recover without medical attention, in the very young, very old and those with impaired immune systems it can develop into a severe illness. In order to avoid it, health experts warn people to never eat raw or undercooked eggs, poultry or meat. It remains to be seen if peanut butter is really responsible for this outbreak.