Shellfish Bacteria

What it is:

Eating shellfish has been related to a number of diseases, including those caused by bacteria, viruses including hepatitis A and Norwalk agent, and those caused by toxins.


Persons who eat raw or undercooked shellfish harvested from sewage contaminated waters may get diarrhea.  If the bad shellfish contains a neurotoxin called saxitoxin and it is eaten in high doses, it can lead to diaphragmatic paralysis, respiratory failure and death.

 Associated foods:

Any edible, aquatic invertebrate with a shell such as clams, mussels, scallops and oysters


  •  Shellfish foodborne infections caused by bacteria and viruses can be prevented by cooking seafood’s thoroughly, storing them properly, and protecting them from contamination after cooking. Traditional methods of cooking seafood’s, such as steaming clams only until they open, may be insufficient to kill all bacteria and viruses in them.

  •  Shellfish infections caused by toxins are different.  Shellfish containing toxins may look and taste normal, and usual cooking methods do not affect the toxin.  Some of the toxins or poisons that contaminate the shellfish are paralytic shellfish poison, neurologic shellfish poison, diarrheic shellfish poison, and amnesic shellfish poison.

  •   Consumers should be aware of the potential risk to their health, particularly if they eat shellfish from unapproved harvest beds.  For normal persons who eat raw shellfish from approved harvest beds, the risk is likely to be small, although there is no way to totally eliminate all risk.


There are no laboratory tests to detect toxins within an individual. There are no anti-toxins or antidotes available for treatment of shellfish poisoning, and no other chemotherapy has proven effective. Therefore, treatment is supportive care of infected person. Ingestion of alcohol increases absorption of the toxin.  Evacuation of stomach contents may help by removing remaining toxin-containing shellfish.

People at risk:

Persons with underlying disease such as liver disease, diabetes, or disorders of their immune system, are at much higher risk than normal persons for acquiring severe or even fatal illnesses from eating raw shellfish.