As many as 11 people have reported getting sick from eating raw oysters contaminated with cholera bacteria in northern Florida, according to officials.

The oysters came from Apalachicola Bay, near Panama City in northern Florida, about 482 kilometres from New Orleans along the Gulf of Mexico coast, and the US Food and Drug Administration issued a warning not to eat them.

State officials said 11 cases of illness were reported, while the FDA said eight of those have so far been confirmed as “caused by toxigenic Vibrio cholerae O75... No one was hospitalized or died.”

The high number of cases is unusual, given that the Centres for Disease Control typically logs one to two cases per year, an FDA spokesman remarked.

“From 2000-2010, a total of 17 persons with toxigenic V. cholerae O75 infection were reported to CDC, the numbers are greatest when the water is warm,” spokesman Douglas Karas said.

The FDA said the affected oysters were harvested from Area 1642 in Apalachicola Bay between March 21 and April 6.

The Florida Department of Agriculture said it closed the area to oyster harvesting on April 29 and was investigating the cause of the outbreak.

“To date, we have learned of two events that may be the cause of the cholera related illnesses. First, there was a dredging operation near the 1642 harvesting area that may have stirred up organisms on the floor of the ocean,” it said.

“We have also learned there was a sewer break in East Point and we are investigating whether it had any impact on oysters in 1642.”

Oyster samples collected this week in the area were sent to the FDA for analysis and cholera was not found, so the harvesting area will reopen on Wednesday, the agriculture department said.