Shellfishing in Oyster Bay and Cold Spring harbors has been banned while the state Department of Environmental Conservation investigates reports of illnesses from people eating raw clams at two restaurants and a carnival last month.
The suspected bacteria, known as Vibrio parahaemolyticus, are in the same family that causes cholera and are found in brackish waters along the coast. Typically peaking during summer, it most often sickens people who eat raw or undercooked shellfish.
"The symptoms are diarrhea, abdominal pain, nausea, chills and headaches," said Mary Ellen Laurain, Nassau County Department of Health spokeswoman. Symptoms occur between four and 96 hours after exposure but the average is 15 hours, she said.
The closure affects 4,800 acres of shellfishing waters in Oyster Bay and Huntington towns. "It's a pretty significant area to have affected and people have been fearing it for some time," said Christopher Gobler, a professor at Stony Brook University's School of Marine and Atmospheric Sciences.
The DEC is awaiting test results from the state Department of Health to confirm whether the reported illnesses were caused by the bacteria, agency spokeswoman Lori Severino said.
She did not provide the number of cases but said reports had been coming from state and local health officials. "It's all still under investigation," Severino said.
Nassau County received two reports from eating raw clams -- one at a restaurant June 5 and 6, the other at a carnival June 15. Both people recovered, Laurain said.
County officials started an investigation after receiving the reports, asking the victims where they went, what they ate, whether anyone else got sick and how long the symptoms lasted. "It's basically a history," Laurain said.
Suffolk County had one confirmed case of a person testing positive for the bacteria after eating raw shellfish. A second case is under investigation, Suffolk County Health Department spokeswoman Grace Kelly-McGovern said.
State Department of Health officials did not respond to a request for comment.
Oyster Bay Harbor was closed for several weeks last year after the bacteria were confirmed there and eight people were sickened, DEC said.