By
Jose Ceja
Arizona Daily Wildcat
Raw shellfish contain high instances of salmonella,
A few years ago, Lynn Joens would have been glad to indulge in a fresh plate of oysters on the half shell.
But, Joens has since abstained of this delicacy because of high instances of salmonella and campylobacter that have been found in the popular shellfish.
Joens, a veterinary sciences and microbiology professor, is among a team of researchers who want to determine the extent of shellfish contamination by salmonella and campylobacter across the United States.
With help from the Food and Drug Administration and the North Carolina Department of Fisheries, Joens and his colleagues have collected oysters and clams from Oregon and North Carolina.
Joens said that in some samples of oysters tested, there was a 50 to 70 percent instance of salmonella - a bacteria causing fever, diarrhea and food poisoning.
Campylobacter - which causes similar symptoms in humans - was found in about 10 to 15 percent of some of the samples, Joens said.
Joens said that current FDA shellfish testing standards for salmonella and campylobacter may be too lax to prevent contamination.
Shellfish are only tested for E. coli and not for diseases such as salmonella and campylobacter, he said.
"They would never pick up anything else," he said.
John Mare, a UA professor emeritus of veterinary sciences and microbiology who has been working on the project, said shellfish do not naturally contain salmonella or campylobacter but acquire them by acting as "filters" in their environments. Oysters filter as much as seven liters of water per hour, he said.
Feces, coming from animals and humans, is responsible for much of the contamination of shellfish and results in salmonella and campylobacter, Mare said.
"They concentrate anything that is in the water," Mare said.
Mare said that shellfish are such efficient collectors of pollution that they have been used to trace the source of the contaminants.
Eventually, the study - which is being funded by the UA - will present recommendations to the FDA on how to improve standards used to test the safety of shellfish.
"Pretty much all of them (safety regulations) monitor for far too few things," he said.
Mare said that health threats posed by shellfish are augmented by the fact that they are often eaten raw. He said cooking shellfish is a way to ensure the contaminants are killed off.
"I sure as hell would not eat them raw," he said.
Jose Ceja can be reached at jose.ceja@wildcat.arizona.edu.
