Oregon public health officials issued a warning for illegally imported cheese from Mexico that is believed responsible for giving an unborn baby Listeria.

The infection was traced to unlabeled soft cheese called queso fresco sold in a Latino grocery store in Woodburn, officials said in a release. The investigation by the Public Health Division and the Oregon Department of Agriculture found the cheese was brought into the country illegally from Mexico and sold in plastic bags.

A newborn baby became ill in late December, officials said, and believe the baby was infected before being born.