The Union Democrat reports that the possible link between 12 cases of E. coli found in California, Michigan, Missouri and Ohio is still being investigated by the Centers for Disease Control. Strains found in victims in each of those states are extremely similar and could lead to a source of the disease, health experts say.
From the article:

“All of the states that have those cases, it’s not a perfect match, but they are markedly similar,” said Colleen Tracy, Calaveras County public health director. “There are small, subtle differences in the DNA. … We expect to hear about whether they (the CDC) think those cases are related and the source.”
Of the 12 people who got the similar strain of E. coli, three live in Calaveras County, two were from Michigan, five were in Jasper County, Mo., and two others were in Ohio.
“We have not yet identified a source,” Moehr said, adding that officials investigated the children’s recent food histories. “We assume they are connected to the day-care.”
The three cases from Calaveras County that might be linked to the other states’ cases occurred in two brothers from Murphys, ages 14 and 17, and a 13-year-old Angels Camp boy. The three exhibited cattle at the Calaveras County Fair and Jumping Frog Jubilee, held May 13-16.
It has not been confirmed that the teens contracted the infections at the fairgrounds, but county public health officials said they each share that common history.