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Vibriosis (Non-Cholera)

Information for Local Health Departments

Vibrio species are bacteria that naturally occur in marine environments or brackish water (a mixture of fresh and salt water, which is often found where rivers meet the sea and in estuaries). Infection with Vibrio can cause two distinct types of illness: cholera and vibriosis. The information on this webpage pertains to non-cholera Vibrio species and vibriosis specifically. For more information about cholera, which is caused by other strains of Vibrio (i.e., toxigenic Vibrio cholerae serogroup O1 or O139), please visit the CDC Cholera website.  

More than 20 non-cholera Vibrio species can cause human illness (vibriosis), accounting for an estimat​ed 80,000 illne​sses, 500 ​hospitalizations, and 100 death​s each year in the United States. Non-cholera Vibrio species most frequently cause gastrointestinal illness but may also cause infections ranging from wound or ear infections to severe systemic disease.

In the U.S., the most common non-cholera Vibrio species causing vibriosis are V. parahaemolyticus, V. alginolyticus, V. vulnificus, and non-toxigenic V. cholerae. Consuming raw or undercooked shellfish is the most common cause of vibriosis. Exposing wounds to seawater or contaminated raw shellfish harvested from such waters can also cause skin or soft tissue Vibrio infection.

​Vibriosis in California

Vibriosis cases in California have been reported year-round, but more than 70% of cases occur during June through October, when water temperatures are warmer. In recent years, California patients have been involved in vibriosis outbreaks due to shellfish contaminated with Vibrio, particularly oysters. While most cases of vibriosis appear to be sporadic rather than outbreak-related, there have been outbreaks associated with raw oyster consumption from certain harvest or growing areas. Thus, it is important for local health departments (LHDs) to follow up with patients with Vibrio infection. ​

Complete epidemiologic and seafood traceback information collected in a timely manner will enable the California Department of Public Health (CDPH) to identify the likely source of infection, identify specific shellfish growing regions where contamination could have occurred, and implement potential regulatory action to prevent additional illnesses. If an outbreak occurs, CDPH can recall contaminated seafood, close California waters, and notify authorities from the states where shellfish are grown and harvested. The CDPH Shellfish Program regularly monitors coastal and brackish waters in California where shellfish are grown and harvested to make sure that shellfish are safe for people to eat.

Healthcare providers are required to report suspected cases of Vibrio infections to the LHD within one working day of identification or immediately by telephone if an outbreak is suspected. Clinical laboratories are required to report laboratory testing results suggestive of Vibrio species within one working day after the healthcare provider has been notified of the laboratory testing result.

Interviewing Patients

  • It is important to interview patients as soon as possible after they are identified for more accurate recall of food and other exposures.

  • Please use the CalREDIE tabs or CDPH Cholera and Other Vibrio Illness case report form (CDPH 8587 PDF in the CalREDIE Document Repository).

  • If a patient reports seafood exposure, the CDC Cholera and Other Vibrio Illness Seafood Investigation Report Form (Section 5 of COVIS, CDC OMB 0920-0728) should also be completed (available in CalREDIE document repository).

LHDs may need to restrict the activities of persons with Vibrio infection from certain work or activities (such as food handling, health care, or day care) until their symptoms have resolved. All patients with vibriosis should be educated regarding disease transmission. Note that direct person-to-person transmission does not normally occur.​

For detailed information about reporting and vibriosis case investigation guidelines, please see:

CDPH Infectious Diseases Branch (IDB) Guidance for Non-Cholera Vibrio Infections (PDF)

Updated June 2023

Reporting Resources
  • National Notifiable Diseases Surveillance System Case Definition - Vibriosis​ (any species of the family Vibrionaceae, other than toxigenic Vibrio cholerae O1 or O139) 
  • Council of State and Territorial Epidemiologists (CSTE) Position Statement 16-ID-05 (PDF)
    • ​Per the case definition and position statement, detection or isolation of other species of the family Vibrionaceae will also count as a case. Genera in the family Vibrionaceae currently include: Vibrio, Aliivibrio, Allomonas, Catenococcus, Enterovibrio, Grimontia, Listonella, Photobacterium, and Salinivibrio.​
  • CDC Cholera and Other Vibrio Illness Surveillance (COVIS) Report Form (OMB 0920-0728) (PDF, 2.0MB)
    • CDC’s COVIS Report Form has five sections. It is not necessary for LHDs to complete the entire CDC form (i.e., sections 1-4) because the CDPH case report form (CDPH 8587) and CalREDIE tabs capture the relevant clinical, laboratory, and epidemiologic data.
    • Section 5 of COVIS Report Form (CDC OMB 0920-0728) – Seafood Investigation
        • Photo of a shellfish tag providing harvest and processing information for clams (identifying information redacted).​​If the patient reports seafood exposure, this form should be used to report seafood investigations, which are usually completed by local environmental health staff. A blank copy of the form can be found in the CalREDIE Document Repository. Include copies of available shellfish tags, invoices, labels, and inspection reports. Shellfish tags include information on shellfish type, growing location, harvest date, and the shipper.
Example of shellfish tag for oysters with harvest date, location, and shellfish type highlighted.  ​
Data & Statistics


​  California Data

​  Nation​al Data


Sample Vibriosis Messages to Share

Click an image to view and download (right-click and select "Save image as").

Eating raw oysters can put you at risk for vibriosis, a type of food poisoning.

Suggested Mess​age: 

Raw #oysters may be tasty, but they can harbor harmful bacteria that can make you sick! People can get #vibriosis by eating raw shellfish, especially people with chronic diseases such as liver disease, cancer, and diabetes.

Contaminated oysters don't look, smell, or taste different from any other oyster. Always cook oysters just in case!

Suggested Message: 

Are raw #oysters safer to eat if you add hot sauce, lemon juice, or eat them while drinking alcohol? Nope! Bacteria in raw oysters are only killed if you cook oysters to the right temperature.
Learn tips for cooking shellfish:

Don't risk getting sick! Cook oysters completely before eating.

​​Suggested Message: 

Always fully cook #oysters and other shellfish before eating. Why? Raw or undercooked oysters can be contaminated with bacteria that can cause #vibriosis, a serious type of food poisoning. Learn more:

Prevent skin infections from Vibrio bacteria: avoid seawater if you have an open wound or a new tattoo or piercing.

Suggested Message: 

It’s hot out there! Warm seawater can contain lots of Vibrio bacteria, which can cause serious skin infections, especially if you have open wounds or breaks in the skin. Vibrio bacteria can contaminate seafood and cause food poisoning, too. Learn more:

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