U.S. health officials are investigating a cluster of neurological illnesses in workers at pork slaughter facilities in Indiana and Minnesota.

The Minnesota Department of Health said 12 workers at the Quality Pork Processor plant in Austin, Minn., have reported illnesses characterized by changes in sensation and weakness in the limbs.

The agency said it learned this week that the Indiana Department of Health and the U.S. Centers for Disease Control and Prevention are investigating symptoms reported by several workers at a plant in Indiana to determine if their illnesses are similar to those found in Minnesota.

The investigators are looking closely at a slaughtering procedure that uses high-pressure air to remove brains from the swine head. As a precaution, pork processing plants in Minnesota, Indiana and Nebraska have voluntarily stopped using the technique, Minnesota health officials said in a release.

While extensive viral and bacteriological testing to find a cause for the illnesses continues, no viral pathogens have been identified, the agency said.

Copyright 2008 by United Press International