Two Oregonians have tested positive for a rare strain of Salmonella known as Salmonella overschie, according to the Oregon Health Authority Public Health Division.

The first patient was a 28-year-old Coos County woman who fell ill in December. The second case was a minor in Lane County, which is separated from Coos County by Douglas County.

The two patients developed their symptoms eight days apart. The state health department investigated the possible source of contamination, but couldn’t determine one before ending the investigation.

Authorities say the strain has never before been reported in Oregon. Only 23 cases of Salmonella overschie were detected in the U.S. between 1995 and 2005, according to health officials.

No new cases have surfaced since December.

Salmonella overschie has been known of since at least 1961, when it was isolated from a patient in the Netherlands.