BATON ROUGE, La. — Louisiana recalls oysters harvested in part of Plaquemines Parish because 11 people at a seafood conference in Mississippi got sick after eating some.

Louisiana’s Department of Health and Hospitals says one person was hospitalized but has since been released.

The conference was March 10.

The recall affects oysters harvested since March 6 from Basin 4, Area 7. Health Officer Jimmy Guidry says the area will probably be closed for at least 21 days.

The recall includes shucked, frozen, breaded and post-harvest processed oysters, and oysters for the half shell market.

The illness was norovirus, which spreads easily and can cause one or two days of severe vomiting, cramps and diarrhea. Symptoms usually begin 24 to 48 hours after exposure.

Cooking kills the virus, but undercooked oysters can spread it.