Oysters served on a plate at restaurant

MEXICO — Oysters from an estuary in Mexico have been linked to a spate of illnesses in the United States, public health authorities announced Friday.

At least 16 people from five states have come down with gastrointestinal illnesses traced back to oysters harvested from an estuary in Baja California Sur, Mexico, according to the US Centers for Disease Control and Prevention. Two people have been hospitalized, and there have been no reported deaths.

The agency, which is investigating the outbreak, warned consumers to refrain from eating or selling oysters from the estuary in question, Estero El Cardon, whose growing area has been closed since Tuesday. At least one distributor of these oysters has issued a recall.

The CDC has identified a number of pathogens among people who have gotten sick, including Vibrio and Shigella bacteria. The majority of cases have occurred among residents of California, where the oysters were shipped. People who fell ill reported ordering raw oysters from restaurants in California and Nevada.

According to a statement by the US Food and Drug Administration, authorities do not believe that any more contaminated product is being sold, but an investigation continues into the root cause and scope of the outbreak. The most recent illness linked to the outbreak began April 4, but the first such illness appeared in December.

Experts say oysters can be high-risk because they don’t eat like humans do; instead, they filter water, concentrating bacteria in their tissues. Warmer waters like those around Mexico, as opposed to places like the Pacific Northwest, may also be better environments for bacteria to thrive.

When it comes to the bugs the CDC identified, common symptoms include watery or bloody diarrhea, stomach pain, fever, nausea and vomiting. Symptoms may start within days of infection and last up to a week, the agency said. Those who have other chronic conditions, like weakened immune systems, may be at higher risk.

The CDC recommends cooking raw oysters and shellfish thoroughly before serving them, as well as throwing away oysters whose shells were open before cooking. The agency also stresses the importance of handwashing and disinfecting countertops and utensils that might have come into contact with raw shellfish.