Amounts of Campylobacter were significantly less, at 10 to 15 percent, he says. This tends to clean out the E. coli bacteria. But we found that, while there was a reduction of at least 50 percent of the E. coli and 'campy,' there was no reduction at all of salmonella. Joens says oysters acquire the bacteria by filtering water. The bacteria end up being stored in the meat, making it a dangerous delicacy to eat raw, he says.
Oysters are filter feeders that tend to reflect what is in their environment.
If their waters are contaminated with salmonella, they may become contaminated. In fact, she says oyster contamination has not been a problem since the first half of the 1900s. It used to be a problem when oysters were harvested in waters that were contaminated with human sewage. However, Joens claims that testing only the waters will not reveal the actual levels of salmonella. Between 800,000 and 4 million cases of salmonella are reported each year in the United States, the CDC says.