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Annual Quarantine of Sport-Harvested Mussels in California Begins May 1 

Date: 4/29/2016 
Number: 16-024 
Contact: Susan Fanelli, (916) 440-7259 

SACRAMENTO – California Department of Public Health (CDPH) Director and State Public Health Officer Dr. Karen Smith today announced that the annual quarantine on sport-harvested mussels gathered along the California coast will begin May 1, 2016. This quarantine applies to all species of mussels sport-harvested along the California coast, as well as all bays and estuaries. 

“The quarantine is in place to protect the public against poisoning that can lead to severe illness, including coma and death,” said Smith. “It is critical that the public honor the quarantine because the toxins found in mussels have no known antidotes and they are not reliably destroyed by cooking.” 

This quarantine is intended to prevent paralytic shellfish poisoning (PSP) and domoic acid poisoning (DAP) in people who might otherwise consume sport-harvested mussels. Both of these toxins are linked to plankton consumed by filter-feeding animals such as bivalve shellfish, including mussels and clams. The majority of human cases of PSP illnesses occur between spring and fall. 

Commercially harvested shellfish are not included in the annual quarantine because all commercial shellfish harvesters in California are certified by CDPH and are subject to strict testing requirements to ensure all oysters, clams and mussels entering the marketplace are free of toxins. 

Early symptoms of PSP include tingling of the lips and tongue, which may begin within minutes of eating toxic shellfish. These symptoms are typically followed by a loss of balance, lack of muscular coordination, slurred speech and difficulty swallowing. In severe poisonings, complete muscular paralysis and death from asphyxiation can occur. 

The December 9, 2015 Health Advisory warning consumers not to eat recreationally harvested razor clams from Humboldt and Del Norte counties remains in effect due to continued high levels of domoic acid. Symptoms of DAP, also known as amnesic shellfish poisoning (ASP), can occur within 30 minutes to 24 hours after eating toxic seafood. In mild cases, symptoms may include vomiting, diarrhea, abdominal cramps, headache and dizziness. These symptoms disappear completely within several days. In severe cases, the victim may experience difficulty breathing, confusion, disorientation, seizures, permanent loss of short‑term memory, coma and death. 

More information about the quarantine, PSP and DAP can be found on the CDPH Annual Mussel Quarantine - Frequently Asked Questions (FAQ) Web page. 

For updated information on quarantines and shellfish toxins call the CDPH Biotoxin Information Line (1-800-553-4133).
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