PORTLAND, Ore. -

Oregon health and agriculture officials issued a warning Friday about a type of cheese imported illegally from Mexico believed to be tainted with Listeria and responsible for sickening an infant in December.

The newborn baby lives in Clackamas County and became ill in late December. Physicians with the Oregon Health Authority Public Health Division believe the child was infected with the Listeria bacteria while in the womb. The baby is recovering.

A joint investigation by the Public Health Division and the Oregon Department of Agriculture traced the infection to an unlabeled soft cheese, called queso fresco, manufactured in Mexico and purchased from a Latino grocery store in Woodburn.

Officials believe the cheese was brought into the country illegally, because it was unlabeled and was distributed and sold in plastic bags.

"If people have this cheese in their refrigerators, they should throw it out or take it back to where they bought it," said Paul Cieslak, M.D., manager of the Oregon Public Health Division's Acute & Communicable Disease Prevention section. "Eating it can make people very sick, especially pregnant women, the elderly and those with weakened immune systems."

The Department of Agriculture is issuing placards for businesses to display.

Symptoms of listeriosis include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches. Pregnant women typically experience fever and other non-specific symptoms, such as fatigue and aches.

However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn. Pregnant women or those with compromised immune systems who experience fever after eating queso fresco should see their doctor immediately.

During the past five years in Oregon, there have been 68 cases of listeriosis, an average of 14 cases per year. Seven cases were reported in 2013. About 60 percent of reported listeriosis cases are hospitalized, and about 10 percent of reported cases are fatal. Listeriosis is treatable with antibiotics.

For more information on Listeria, visit the Centers for Disease Control and Prevention website at www.cdc.gov/Listeria/.