Raw milk from Greenfield Dairy near the central Pennsylvania town of Middleburg is likely contaminated with Listeria monocytogenes and should be discarded immediately, state officials say. Raw milk is milk that has not been pasteurized. The Greenfield raw milk has not yet been associated with any illnesses. The dairy’s  milk collected for routine sampling by a commercial laboratory on April 8 tested positive for Listeria bacteria. Greenfield Dairy, located at 1450 Tittle Rd., is owned by Paul Weaver, who sells directly to consumers at an on-farm retail store. The packaged raw milk is sold under the Greenfield Dairy label in half-gallon glass containers dated April 18, 21, 22 and 24.  It is also labeled as “raw milk.” State agriculture officials have ordered the owner of the dairy to stop the sale of all raw milk until further notice. Two samples taken at least 24 hours apart must test negative before the farm can resume raw milk sales. Pennsylvania law allows farms to sell raw milk but requires the farms to be permitted and inspected by the agriculture department to reduce health risks associated with unpasteurized products. There are 175 farms in Pennsylvania permitted to sell raw milk or raw milk cheese. Symptoms of Listeriosis usually appear within one to three weeks, but can be as short as three days or as long as 70 days after consumption and include fever, muscle aches and gastrointestinal symptoms such as nausea or diarrhea. If the 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. Any person who consumed raw milk from Greenfield Dairy and has symptoms should consult their physician or visit their local state health center.