Hazelnuts from a California distributor are being recalled after public health investigators traced seven illnesses, including three in Minnesota, to nuts contaminated with E. coli bacteria.

The Minnesota Health and Agriculture departments announced Friday that bulk in-shell hazelnuts from DeFranco and Sons are being recalled due to the outbreak. The nuts, also known as filberts, are mostly sold in bulk bins, making it difficult to identify those that might have come from the distributor.

A list of markets in Minnesota, Wisconsin and five other states that sold the nuts is available on the Agriculture Department's website.

The three Minnesota infections involved men over age 50 from Hennepin, Stearns and Redwood counties. Two were hospitalized; all three have recovered.

Hazelnuts grow on trees, but they are harvested after they fall to the ground, where the contamination likely occurred, according to Ben Miller of the state Department of Agriculture's dairy and food inspection division.

"The fact that they do spend some time on the ground increases the risk of environmental contamination," he said. The investigation is now focusing on farms in Oregon that produce the majority of U.S. hazelnuts.

E. coli infections typically cause severe stomach pains and diarrhea. Symptoms emerge within two to five days of eating contaminated food. A small fraction of infections can result in more serious complications, including kidney failure.

The bulk nuts were distributed between Nov. 2 and Dec. 22, 2010. In addition, the recall affects packaged nuts under the brands Sunripe Hazelnuts, Sunripe Large Hazelnuts and Sunripe Mixed Nuts. The packaged products have sell-by dates of June 30. The recall does not affect out-of-shell hazelnuts or products containing hazelnuts as an ingredient.

Miller said people might still have contaminated hazelnuts because they have long shelf lives.

Jeremy Olson • 612-673-7744