According to a report by the CDC (Centers for Disease Control and Prevention), about 48 million people in the US fall ill due to eating contaminated foods such as raw oysters. Raw oysters can harbor several organisms such as Vibrio bacteria and norovirus, which can result in food poisoning. Recovery from food poisoning happens within a couple of days in most of the persons. However, life-threatening symptoms may appear in people suffering from HIV, liver disease or cancer due to a specific strain of Vibrio bacteria.

Causes and Symptoms of Oyster Food Poisoning

1. Food Poisoning Due to Norovirus

Norovirus causes approximately half of all the cases of food poisoning that are reported. It is caused due to eating leafy greens, fruits or oysters contaminated by norovirus. The virus may be transferred by contact with a contaminated person or touching a surface that is contaminated. Symptoms appear within 10-48 hours of being exposed to the virus and include watery diarrhea, nausea, vomiting and abdominal cramps. Recovery occurs in healthy adults within 2-3 days without the need of medical care.

2. Food Poisoning Due to Vibrio Bacteria

Vibrio bacteria live in warm waters of the coastal regions such as Gulf of Mexico. Oysters may become contaminated by Vibrio bacteria before harvesting. Symptoms appear within 3-48 hours of consuming contaminated raw oysters (by Vibrio parahaemolyticus) and include diarrhea and vomiting. Symptoms may last for 3-8 days. However, if infection occurs due to Vibrio vulnificus, similar symptoms appear within 1-8 days. The disease may be more severe, especially in susceptible individuals.

Certain health disorders make people prone to develop serious illness or even death from infection with V. vulnificus. Some of these disorders are:

• Liver disorders (such as cirrhosis, hepatitis, cancer or alcohol related liver disease)
• Hemochromatosis (characterized by iron overload)
• Diabetes mellitus
• Stomach disorders
• Cancer (including leukemia, lymphomas and Hodgkin’s disease)
• Any disease or treatment that weakens your immunity such as HIV infection

How to Treat Oyster Food Poisoning

The aim of managing food poisoning resulting from eating contaminated oysters is to replace electrolytes and fluids lost due to diarrhea and vomiting.

• Sip a rehydration drink (for instance Pedialyte) frequently to prevent getting dehydrated. Try to compensate a large stool you pass by drinking a cup of rehydration drink. You should avoid fruit juices and soda to rehydrate as they are loaded with sugar and do not contain enough important electrolytes lost due to food poisoning.
• Serious problems can result due to dehydration. You may need to get hospitalized for severe dehydration where lost fluids and electrolytes are replaced by giving fluids via vein (IV or intravenous fluids). You should immediately call your physician if you feel that you or the person for whom you are a caregiver suffers from severe dehydration.
• Try to stick to your normal diet during illness as it will provide enough nutrition. However, avoid foods high in sugar and fat. Also avoid alcohol, coffee, and spicy foods for at least 2 days after you have recovered from oyster food poisoning.
• Medicines to control vomiting, diarrhea or cramps should be avoided except Pepto-Bismol. These medicines work by reducing the movement of intestines and stomach and can lengthen or aggravate the illness since the agent causing the infection is not expelled out of the body as quickly.
• Antibiotics may be prescribed to individuals who have weakened immune system or to those with severe symptoms.

When Should I Visit a Physician?

You should visit your physician if:

• You have severe diarrhea that lasts for greater than three days.
• You have frequent vomiting that lasts for greater than two days.
• You take diuretics and develop nausea, vomiting or diarrhea.
• You develop high temperature over 101 degrees F.

Seek emergency medical treatment if:

• You pass black or maroon stool or large amount of blood is present in your stool.
• Your vomitus contains blood.
• You develop trouble in breathing.
• You develop severe pain in abdomen or stomach cramps.
• You develop double vision or have trouble in moving different parts of your body.
• You develop symptoms and signs of severe dehydration.
• You have a pounding feeling of your heart.

How to Prevent Oyster Food Poisoning

1. Food Poisoning Due to Norovirus

To prevent infection due to norovirus:

• Make sure to cook oysters and other types of seafood completely before you eat them as raw seafood is usually contaminated with the virus.
• After preparing seafood, wash counters and cutting boards immediately to avoid cross contamination of other foods.
• Wash your hands thoroughly using soap and water after changing diapers or going to bathroom and before cooking or eating any food.
• Wait for at least 2 days after the symptoms of food poisoning disappear before cooking food for others.

2. Food Poisoning Due to Vibrio

You should not eat raw shellfish or raw oysters and cook them thoroughly before eating. Shucked oysters should be boiled for at least 3 minutes or fried in oil for at least 11 minutes at a temperature of 375 degrees F. For shellfish present in the shell:

• You can boil it until the shell opens and continue the boiling process for at least 5 minutes more.
• You can also steam it until the shell opens and continue the steaming process for at least 10 minutes more.
• Discard shellfish that don’t open while cooking.

Also follow the below mentioned tips to prevent food poisoning due to Vibrio:

• Prevent cross-contamination of other foods, juices and cooked seafood with raw seafood. Avoid preparing them on the same counters. Don’t use same cutting board to prepare them.
• Shellfish should be eaten immediately after it is cooked and the leftovers should be refrigerated.
• Don’t expose broken skin or open wounds to brackish water or warm saltwater or to raw shellfish that is harvested in such waters.
• While handling raw shellfish wear protective clothes such as gloves.