Consumers who have purchased raw milk from Fisher's Dairy farm in Portersville, Butler County, should discard it immediately due to the risk of Listeria Monocytogenes contamination, state Agriculture Secretary Dennis Wolff said today.

Raw milk is milk that has not been pasteurized or homogenized. Pennsylvania farms selling raw milk must be permitted and inspected to reduce health risks associated with the unpasteurized products, according to a news release. In 2006, Fisher's Dairy gave up its raw milk permit, but state inspectors found that the dairy had begun selling raw milk again without a permit, according to the release.

"During an investigation of the dairy, inspectors purchased raw milk which tested positive for Listeria Monocytogenes," said Mr. Wolff. "If consumers have raw milk from this farm, they should discard it immediately."

No illnesses have been reported as a result of the potential contamination, but if people who consumed the raw milk become ill, they should consult their physicians.

According to the release, the state Department of Agriculture has embargoed all milk products at the farm. Samples were taken from the farm last Thursday and tested positive for Listeria Monocytogenes on Monday.

Symptoms of Listeriosis are fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance or convulsions can occur.

Infected pregnant women may experience only a mild, flu-like illness, but infections during pregnancy can lead to miscarriage or stillbirth.

Symptoms of Listeriosis can appear in four days to three weeks.