Multistate Outbreak of Gastrointestinal Illnesses Linked to Oysters Imported from Mexico

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May 22, 2019 at 5:15 PM ET

CDC and public health and regulatory officials in several states are investigating a multistate outbreak of gastrointestinal illnesses linked to raw oysters harvested from Estero El Cardon estuary in Baja California Sur, Mexico.

On May 6, one U.S. distributor of oysters harvested from Estero El Cardon issued a voluntary recall pdf icon[PDF – 197 KB]external icon.

On May 7, Estero El Cardon was closed to further oyster harvesting pdf icon[PDF – 491 KB]external icon pending investigation. At the request of Mexico’s public health authorities, all raw oysters distributed from the last week of April through the first week of May have been recalled pdf icon[PDF – 474 KB]external icon.

Advice to Consumers, Restaurants, and Retailers
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At A Glance
Photo of oysters.
  • Do not eat, serve, or sell oysters harvested from Estero El Cardon, an estuaryexternal icon in Baja California Sur, Mexico.
    • Throw away any products with harvest tags that indicate a growing area of Estero El Cardon.
  • Do not eat raw or undercooked oysters or other shellfish. Cook them thoroughly before eating.

Raw Oyster and Shellfish Handling and Cooking Tips

  • Any raw oysters, and not just the raw oysters linked to this outbreak, could contain harmful germs that could make you sick. Don’t eat raw or undercooked oysters or other shellfish. Cook them thoroughly before eating.
  • Always wash your hands with soap and water after handling raw shellfish.
  • Handling oysters and other shellfish:
    • Raw oysters and other shellfish that contain harmful bacteria or viruses may look, smell, and taste normal.
    • Before cooking, discard any oysters with open shells.
    • Keep cooked and raw oysters separate.
    • Wash items that come into contact with raw shellfish and their juices—including countertops, utensils, dishes, and cutting boards—with soap and water.
  • Cooking oysters:
    • When cooking oysters in the shell:
      • Boil until the shells open and continue boiling another 3-5 minutes, OR
      • Add to a steamer when water is already steaming, and cook for another 4-9 minutes.
      • Only eat oysters that open during cooking. Throw out any oysters that do not open fully after cooking.
    • For shucked oysters:
      • Boil for at least 3 minutes,
      • Fry in oil for at least 3 minutes at 375° Fahrenheit,
      • Broil 3 inches from heat for 3 minutes, OR
      • Bake at 450° Fahrenheit for 10 minutes.
  • Restaurants and retailers should:
    • Clean refrigerators, cutting boards and countertops, and utensils that come into contact with raw oysters or their juice. Then, sanitize the surfaces with a solution of one tablespoon of chlorine bleach to one gallon of hot water and dry with a clean cloth or paper towel.
    • Clean and sanitize display cases, surfaces, and any reusable containers used to store, serve, or prepare raw oysters or their juice.
    • Wash hands with soap and water after cleaning and sanitizing.
Latest Outbreak Information
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  • Sixteen ill people from five states have been reported as part of the outbreak.
  • Laboratory testing on samples from patients identified multiple pathogens causing infections. Some people were infected with more than one pathogen.
  • Case counts by pathogen or illness:
    • Four cases of Shigella flexneri infection
    • Two cases of Vibrio parahaemolyticus infection
    • One case of Vibrio parahaemolyticus and Shiga toxin-producing Escherichia coli (STEC) non-O157 coinfection
    • One case of Vibrio parahaemolyticus and Shigella flexneri coinfection
    • One case of Shigella flexneri and Campylobacter lari coinfection
    • One case of Vibrio albensis infection
    • One case of norovirus genogroup 1 infection
    • One case of infection with Vibrio of unknown species
    • Four cases of illness without a pathogen identified
  • Epidemiologic and traceback evidence indicates that raw oysters harvested from Estero El Cardon in Baja California Sur, Mexico, are a likely source of this outbreak.
    • Ill people reported eating raw oysters sold by restaurants in California and Nevada.
  • One U.S. distributor of oysters harvested from Estero El Cardon has issued a voluntary recall pdf icon[PDF – 197 KB]external icon.
  • At the request of Mexico’s public health authorities, all raw oysters distributed from the last week of April through the first week of May have been recalled pdf icon[PDF – 474 KB]external icon.
  • Tell your doctor if you think you became sick after eating raw or undercooked oysters.
  • This investigation is ongoing. CDC will provide updates when more information is available.
Common Symptoms of Infection
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Protect Yourself

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Shigella spreads easily from one person to another. Find out how you can help keep yourself and your loved ones from getting sick. Get tips >

Common symptoms of illness caused by the pathogens (Vibrio, Shigella, norovirus, STEC, and Campylobacter) involved in this outbreak include:

  • Diarrhea (that may be watery or bloody)
  • Stomach cramps or pain
  • Nausea
  • Vomiting
  • Fever

Symptoms typically start from 1 to 4 days after the pathogen is consumed and last from 1 day to 1 week. Most people recover without treatment.

You may develop a more serious illness if you have certain medical conditions, such as liver disease or an immune system weakened from HIV, other health problems, or chemotherapy.

Call the doctor if you have:

  • Diarrhea and a fever higher than 102°F
  • Diarrhea for more than 3 days that is not improving
  • Bloody stools (poop)
  • Prolonged vomiting that prevents you from keeping liquids down
  • Signs of dehydration, such as:
    • Making very little urine
    • Dry mouth and throat
    • Dizziness when standing up
Investigation Details

May 22, 2019

Since the last update on May 10, 2019, one ill person was added to this outbreak. Another ill person was excluded from this outbreak because additional laboratory evidence did not support a link to raw oysters harvested from Estero El Cardon.

As of May 22, 2019, 16 ill people have been reported from five states. Ill people in this outbreak have been infected with multiple pathogens causing illness, including Vibrio parahaemolyticus, Shigella flexneri, STEC non-O157, Vibrio albensis, Campylobacter lari, and norovirus genogroup 1.

Illnesses started on dates ranging from December 16, 2018 to April 17, 2019. Among 15 people with information available, ages range from 26 to 80 years, with a median age of 38. Sixty percent are male. Of 15 people with clinical information available, 2 (13%) hospitalizations were reported.

A list of the states reporting people linked to the outbreak and the number of cases in each state can be found on the Map of Reported Cases page.

State health officials have reported two additional ill people to CDC who are not included in the number of cases linked to the outbreak. These people did not consume raw oysters but they did have contact with one of the people in the outbreak with a Shigella flexneri infection. Shigella spreads easily from one person to another. See prevention tips.

Illnesses that occurred after April 17, 2019, might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This can take 4 or more weeks.

Investigation of the Outbreak

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are investigating illnesses linked to raw oysters harvested from Estero El Cardon estuary in Baja California Sur, Mexico. This multistate investigation began on March 29, 2019, when the PulseNet system identified a cluster of closely related Vibrio parahaemolyticus bacteria in samples isolated from ill people. Epidemiologic and traceback evidence indicated that people ate raw oysters harvested from Estero El Cardon (an estuary) in Baja California Sur, Mexico. State public health officials identified additional illnesses among people who also ate raw oysters from the same harvest area. FDA is investigating a subset of illnesses currently being investigated by the CDC.

In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill. All 15 people who were interviewed reported eating raw oysters from different restaurants in California and Nevada. State health officials collected traceback information for 15 cases and found that oysters were shipped by Sol Azul, S.A. de C.V. (MX 01 SS) and harvested from Estero El Cardon. These oysters were distributed to California, Nevada, New York, and Arizona. It is possible that additional states received these oysters either directly from Mexico or through further distribution within the United States. Oysters were sold to wholesale distributors with direct sales to restaurants. The oysters were not sold to grocery retail outlets.

On May 6, one U.S. distributor of oysters harvested from Estero El Cardon issued a voluntary recall pdf icon[PDF – 197 KB].external icon On May 7, Estero El Cardon was closed to further oyster harvesting pdf icon[PDF – 491 KB]external icon pending investigation. At the request of Mexico’s public health authorities, all raw oysters distributed from the last week of April through the first week of May have been recalled. FDA continues to work with Mexico’s health authorities, and state and local partners continue to verify that this product has been successfully removed from commerce and to ensure that the raw oysters were not further distributed. For more information, see the Mexico recall notice. pdf icon[PDF – 474 KB]external icon

This investigation is ongoing. CDC will provide updates when more information is available.

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