WASHINGTON, D.C. -- The Listeria Outbreak Working Group, a collaboration of scientists and public health professionals organized by Cornell University, has won the prestigious U.S. Department of Agriculture Honor Award, one of the highest awards bestowed by the agency.

The listeria group, led by Martin Wiedmann, Cornell assistant professor of food science, was singled out for its effort in 1998 and 1999 to discover a food-borne listeria outbreak in many states. The award was made in the category of "Ensuring food for the hungry and a safe, affordable, nutritious food supply."

Wiedmann and Kathryn Boor, Cornell assistant professor of food science, accepted the award on behalf of the group from Secretary of Agriculture Dan Glickman at a ceremony in the Ronald Reagan International Trade Center on June 5.

In response to an increase in listeria cases observed by the state health departments in Connecticut, New York, Ohio and Tennessee, the Listeria Outbreak Working Group came together in November 1998. Listeriosis, a severe food-borne disease caused by the bacterium Listeria monocytogenes, results in death for approximately 20 percent of affected humans. Currently, listeria causes 2,500 cases of food-borne illness and 500 deaths annually in the United States.

Between October 1998 and Feb. 2, 1999, more than 100 people became ill and 21 people died nationally as a result of eating food contaminated with a rare strain of the listeria bacterium, called Type E. Wiedmann's discovery of the strain led the Centers for Disease Control and Prevention (CDC) in Atlanta to determine Type E was the cause of the outbreak.

Wiedmann has been collecting samples of the bacterium L. monocytogenes for several years and identifying each strain's unique genetic fingerprint. Every month the New York State Department of Health sends him up to six strains, which he identifies and adds to a database. He also receives listeria strains from tainted food sent by the New York State Department of Agriculture and Markets and from Patrick L. McDonough, assistant professor at Cornell's New York State Veterinary Diagnostic Laboratory. Wiedmann has developed a listeria database of nearly 800 strains.

Typically, there are up to six cases of listeriosis a month in New York state, normally caused by different strains of L. monocytogenes. But in October 1998, Wiedmann received 15 samples of listeria from the New York State Department of Health -- more than double the normal amount. The samples were sent to Mary S. Bodis, a research support specialist in the laboratory of Carl A. Batt, Cornell professor of food science, for ribotyping, a method of determining genetic fingerprints.

Seven of the 15 samples had identical genetic fingerprints, meaning that the same strain had caused the illness in seven of the victims. Wiedmann sent the information to the New York health department and to the CDC. The federal agency also had noticed a rise in the number of listeria cases, but until Wiedmann's discovery, it didn't know which strain to look for.

The CDC traced the October 1998 outbreak to consumption of hot dogs and was able to locate and test one of the contaminated products, which was found to be positive for the L. monocytogenes Type E strain.

Prior to using DNA-based identification, food samples had to be collected and examined for the presence of bacteria. The researchers then used the process of elimination to categorize the organisms in an attempt to find which one was linked to the disease, a process that took many weeks. Now, thanks to ribotyping and other methods, such as polymerase chain reaction, the identification and typing processes have been greatly speeded up.

Other members of the Listeria Outbreak Working Group are: Pat Mshar of the Connecticut Department of Health; Farzad Mostashari of the New York City Department of Health; Claudette Farchione and Jon Schermerhorn of the New York State Department of Agriculture and Markets; Dale Morse and Brian Sauders of the New York State Department of Health; Tammy Bannerman and Ellen Salehi, Ohio Department of Health; Robert Taylor of the Tennessee Department of Health; and Eileen F. Dunne, Lewis Graves and Paul Mead of the CDC.