PORTLAND – A third person in Maine has been sickened from the same strain of E. coli bacteria that was linked to a national outbreak arising from tainted spinach, state health officials said Thursday.

The latest confirmed case involved a young woman from Kennebec County who was treated in late August and was reported to be doing fine. It was not clear whether she had eaten spinach, said Dora Ann Mills, director of the Maine Center for Disease Control and Prevention.

The two previous cases involved a resident of Kennebec County and one from Aroostook County, both of whom have recovered.

Federal investigators seeking to pinpoint the origin of the outbreak have been focusing on nine farms in California’s greater Salinas Valley.

While bagged spinach has been recalled and can no longer be found on supermarket shelves, state agriculture officials noted that Maine consumers will have locally grown alternatives for at least another month.

“The fresh spinach at the heart of the current E. coli outbreak was grown and processed in the western United States. We in the Maine Department of Agriculture are working hard to make locally grown food more available to Maine consumers,” said Commissioner Seth Bradstreet III.

Mills said all fresh produce should be thoroughly washed, no matter where it comes from.