The Illinois Health Department has released its investigation into this summer's hepatitis A outbreak. It concluded the source of most of cases was food eaten at the Milan McDonald's.

The first case of hepatitis A in the Quad city area was discovered last June. As we first reported back then, the first confirmed case of the liver illness was an employee at the Milan McDonald's. Over the next two months, a total of 34 confirmed hepatitis A cases were reported.

A state investigation has concluded most of the cases originated at the Milan McDonald's and most of the cases *would have been prevented* if only that one employee had properly washed hands.

The findings of the investigation by the Illinois Department of Public Health concludes "the index case was a food handler at the McDonalds in Milan, Illinois and had onset of illness June 11." Investigators also found "other possible sources in the community were ruled out."

And, "The source of the outbreak for the majority of outbreak cases was food eaten at the McDonalds, Milan, Illinois where a food handler worked while infectious and handled foods that were not later cooked."

The state investigation goes on to say that "if the first employee with hepatitis A had used proper hand-washing technique while working the transmission of hepatitis A through food would not have occurred."

And, "proper hand-washing by the index case would have prevented the majority of the cases in the community. Reporting of the index case by designated reporters before June 25 would have.. reduced the number of cases in the community."

Dates are important in this story.

The first case was confirmed June 17th, but it wasn't reported to the health department until June 26th. By then, it was too late to medically treat co-workers to prevent the spread.

Also, the Rock Island County Health Department received notice of the case on June 26th, but because a staff member was on vacation, the health department didn't react until July 14th, nearly three weeks later.

McDonald's gave us the following statement on this story:  "McDonald's would never knowingly jeopardize the health or safety of our customers and employees. As previously stated, once our franchisee was notified about this matter by the Rock Island County Health Department on July 13, 2009, he took immediate action to address their concerns. He did everything to meet and exceed the Rock Island County Health Department's requirements."

The Rock Island County Health Department has not returned our calls.