Bacteria lives on a half shell
By BEN LEACH Staff Writer, 609-272-7261
Published: Sunday, June 08, 2008
From the Press of Atlantic City:
http://www.pressofatlanticcity.com/185/story/177776.html

COMMERCIAL TOWNSHIP - Researchers have discovered strains of bacteria carried by shellfish in the Delaware Bay that could pose a threat to human health.
U.S. Department of Agriculture research-ers have found two potentially dangerous species of the bacteria shewanella and one species of photobacterium in oysters and seawater in the Delaware Bay. The bacteria could potentially harm people through skin and blood infections, according to this month's edition of Applied and Environmental Microbiology.

"This was a wake-up call to monitor the shore more closely," said Gary Richards, lead author of the two-year study and lead scientist for the USDA's Agricultural Research Service Seafood Safety Laboratory in Dover, Del.

The bacteria do not come from pollution; instead, they naturally occur in marine waters. This is the first time the bacteria have been discovered in the Delaware Bay, but Richards supposes that they could have been there for a very long time - perhaps even millions of years.

While most healthy people are not at risk of contracting the bacteria, people with weakened immune systems should be concerned.

"The only people it affects are people who are compromised to begin with, and those people shouldn't be eating raw shellfish anyway," said Dave Bushek, another author of the study who works as an assistant professor of marine science at Rutgers University's Haskin Shellfish Lab in Commercial Township, Cumberland County.
Symptoms such as cellulitis, septicemia, and ear and wound infections have been documented in cases of people who have contracted these bacteria.

Bacteria in oysters have caused death. George Walters, late husband of Stone Harbor Mayor Suzanne Williams, died from bacteria called Vibrio vulnificus after eating oysters while on vacation in Florida, although not all strains of that bacteria pose a threat to people's health. Shewanella and photobacterium have very similar DNA.

"The current risk of illness, even though low (for most people), warrants paying attention to the levels of these pathogens over time," Richards said.

Delaware Bay oystermen are no strangers to bacteria from the vibrio family. In 2001, someone was sickened after eating what was believed to be a local oyster, but some oysterman doubt it came from the bay. State Department of Environmental Protection biologists believe the bad oyster was tainted by naturally occurring vibrio parahaemolyticus bacteria in its non-pathogenic form.

"When people hear vibrio - this is very important - people think vibrio vulnificus that's found in the southern states," said DEP biologist Russ Babb, who is assigned to the Delaware Bay area. "This is not that."

Regardless, oyster companies have voluntarily shut down their harvests for two weeks in June each of the last five years as a precaution. They'll do so again for the last two weeks of this June to account for temperatures and other factors that increase the prevalence of vibrio during that period.

"If you think about an industry shutting down proactively, that's impressive, at least in my book," Babb said.

Oyster harvests have also been restricted to the hours of 7 a.m. to 3:30 p.m. Starting Monday, those hours will be limited to 6 a.m. to noon. Bacteria flourish in higher temps, Babb said.

Oystermen also must keep shaded tarps over their oysters on their boats, according to veteran oysterman Barney Hollinger, head of the Delaware Bay Shellfish Council.

The Delaware Bay was once one of the nation's strongest oyster-producing regions. Then disease struck. MSX killed nearly all the bay's oysters beginning in the late 1950s, and Dermo depleted the stocks again in the 1990s.

Over the last few years, oyster populations have improved, bolstered by new methods of cultivation and government-funded efforts to dump new shell upon which oysters can breed.

In 2005, biologists recommended harvesting only 26,000 bushels for the entire year, one of the smallest marks in 50 years.

By 2007, prospects improved to the point where the allocation was 80,000 bushels. This year's total is 76,106 bushels, to be divided among 77 oyster boats.

"Part of it's due to the shell planting," said John Kraeuter, associate director of the Haskin Lab. "That's been adding substantial numbers to the allocation."

To e-mail Ben Leach at The Press: BLeach@pressofac.com

To e-mail Daniel Walsh at The Press: DWalsh@pressofac.com