At least 12 people in five states have been sickened by a rare strain of E. coli linked to raw clover sprouts served at Jimmy Johns Gourmet Sandwiches restaurants, federal health officials reported Wednesday.

The victims fell ill in late December and mid-January, apparently after they ate clover sprouts grown from seeds contaminated with E. coli O26. That strain is similar to, but not as common as the E. coli O157:H7 often associated with illness outbreaks caused by ground beef.

More victims may be pending, officials with the Centers for Disease Control and Prevention indicated.

Traceback information has identified a common lot of clover seeds used to grow the sprouts, CDC officials said. The strain of E. coli O126 has rarely been identified before in PulseNet, the CDC’s surveillance tool.

The bacteria responsible for the Jimmy Johns outbreak are part of a group known as Shiga toxin-producing E. coli, or STEC, which make poisons that can cause severe disease, including bloody diarrhea and hemolytic uremic syndrome, or HUS, which can be fatal.

A widespread outbreak of another non-O157 STEC was responsible for devastating illnesses in Europe last summer, a crisis eventually traced to contaminated sprout seeds.

In the current outbreak, victims were sickened in five states, including five in Iowa, three in Missouri, two in Kansas and one each in Arkansas and Wisconsin, the CDC said.

Ill people ranged between 9 and 49 years old; all were female. Among the 12 sickened, 2 were hospitalized. Illnesses were reported between Dec. 25, 2011 and Jan. 15, 2012.

Illnesses that occurred after Jan. 27 might not have been logged yet because of the time it takes between when a person becomes ill and when the case is reported.

This is the fourth outbreak tied to sprouts served at Jimmy Johns restaurants. Previous outbreaks were logged in 2008, 2009 and 2010, according to CDC reports.