Health officials will begin testing shellfish this week along the South County shoreline for a bacteria contamination already discovered in mussels, clams, scallops and oysters along San Diego County's coast.
San Diego County health officials issued an advisory last week warning residents not to eat shellfish picked up along the coast because it might cause an upset stomach or diarrhea, or more severe illness such as hepatitis. So far, no illnesses have been reported, said Gary Stephany, deputy director of San Diego County's environmental health services.
The warning, issued Wednesday, has prompted Orange County officials to conduct a series of tests this week to see if the bacteria has spread to this county, although preliminary investigations have turned up no signs of bacteria that would warrant any advisories or beach closures, said Dr. Rex Ehling, director of public health. Ocean waters are tested regularly, he said.
Although San Diego County officials tested shellfish from Oceanside to San Diego Bay, the entire county coast from the Mexican border to San Onofre is included in their warning.
"That brings into question, 'What about San Clemente?' " Ehling said.
Fecal coliform bacteria, often found in sewage, was discovered during two studies of bivalve shellfish that started late last year.
In June, high levels of fecal coliform were found at Seafarms West in Carlsbad, the only U.S. commercial grower of bivalve shellfish south of Santa Barbara. Since then, the grower has been filtering and disinfecting the water used by its shellfish.
San Diego County officials started sampling mussels from Oceanside to San Diego Bay in November. Because bivalves have similar feeding systems, county officials presume that clams, scallops and oysters are also contaminated.
The state then conducted tests by putting uncontaminated mussels in San Diego County waters and retesting them. Those tests in December verified the county's finding of high levels of bacteria in the ocean.
The contamination, county officials said, is believed to be caused by sewage or water runoff, which have been more difficult to control as the county becomes more populated.
The advisory does not apply to shrimp, crabs, lobsters or other crustaceans, which have different feeding systems than bivalve shellfish. It also doesn't apply to commercially sold shellfish, which are inspected by state and federal authorities before they go to markets and restaurants.
Officials also say that the bacteria level is not high enough to hurt swimmers.
Ehling doubted whether the San Diego County findings could be related to a recent 250,000-gallon sewage spill in Fountain Valley that forced the closure of 4 1/2 miles of beaches from Beach Boulevard in Huntington Beach to the Newport Pier in Newport Beach.