The Iowa Department of Public Health has done D-N-A testing on germs to verify the source of a strain that sickened dozens of people. Health Department spokesman Kevin Teale says they learned several important things about the strain of e-coli that turned up at a restaurant chain.

Public health labs in Iowa and Minnesota found the outbreaks of e-coli in both states are “genetically matched — meaning the outbreaks are related,” according to Teale. He says those tests also show the germ is not related to any that’s caused other outbreaks across the nation. That means there is link between cases tied to a Cedar Falls Taco John’s restaurant and a Taco John’s in Albert Lea, Minnesota.

It also signals the likelihood that this regional outbreak is not related to illness blamed on food from some Taco Bell franchises across the country. So what food item on the Taco John’s menu was the culprit? Interviews with victims of the Midwest outbreak have given health officials enough information that they now think lettuce is “epidemiologically indicated” as the source of the outbreak, though they’re still doing more tests.

On Wednesday managers of the Taco John’s chain announced they’d canceled their contract with the St. Paul supplier of fresh produce they’ve used up to now.