Vibriosis (Non-CHolera)

Information for Health Professionals

Vibrio species are natural inhabitants of marine coastal and estuarine environments, and their populations increase during the warm summer months. Shellfish (e.g., oysters, clams, mussels, crabs, shrimp, etc.) and other fish that live in these waters can become contaminated. More than 20 non-cholera Vibrio species can cause human illness (vibriosis), accounting for an estimated 80,000 illnesses, 500 hospitalizations, and 100 deaths 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.

Infection with Vibrio can cause two distinct types of illness: cholera and vibriosis. The information on this webpage specifically pertains to non-cholera Vibrio species and vibriosis. 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.

In the U.S., the most common species causing vibriosis are V. parahaemolyticus, V. alginolyticus, and V. vulnificus.

V. parahaemolyticus infection generally presents as acute gastroenteritis with fever that usually occurs after an incubation period of 24 hours. Symptoms usually last 1–7 days and are often self-limited.
V. alginolyticus often causes soft tissue infections, including those involving the eye and ear.
V. vulnificus can cause primary sepsis or serious wound infections. It is the leading cause of shellfish-associated death in the U.S. Sepsis is often accompanied by distinctive bullous skin lesions filled with hemorrhagic fluid. Systemic disease is frequently fatal, especially in persons with chronic liver disease, immunodeficiency, iron storage issues, end-stage renal disease, or diabetes.

Transmission

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; similarly, ear infection can also result. Because Vibrio species thrive in warm water temperatures, infections occur more often during the summer months.

Diagnosis

Diagnosing a Vibrio infection requires testing a clinical specimen, such as stool, blood, or wound. The test can be a culture-independent diagnostic test that detects genetic material of the bacteria or a culture that isolates the bacteria. Healthcare providers suspecting vibriosis should notify the laboratory so that the appropriate selective culture medium, usually thiosulfate-citrate-bile salts-sucrose (TCBS) agar for stool specimens, can be used to isolate the organism. Confirmation of Vibrio through culture is ideal because many culture-independent diagnostic tests do not differentiate between different Vibrio species, which may be necessary to direct treatment and management. In addition, culture confirmation enables public health scientists to determine the species, identify antibiotic resistance characteristics, and perform whole genome sequencing for outbreak detection.

Management

Key Points

Vibriosis should be considered in a patient presenting with watery diarrhea who has eaten raw or undercooked seafood, especially oysters, or with a wound infection following exposure to seawater.
High clinical suspicion and early initiation of treatment for invasive vibriosis, especially due to V. vulnificus is important because these cases may progress rapidly to death.
Culture confirmation is ideal because many culture-independent diagnostic tests do not differentiate between different Vibrio species, which may be necessary to decide on treatment and management.
Healthcare providers are required to report cases of vibriosis to the local health department within one working day of identification or immediately by telephone if an outbreak is suspected.

To aid in proper management of vibriosis:

Patients with gastrointestinal illness should be instructed to hydrate adequately to replace fluids lost through diarrhea.
Patients with certain medical conditions are at increased risk for serious infection from vibriosis, including those with liver disease, hemochromatosis, alcohol abuse, and chronic diseases such as cancer, diabetes, and renal disease.
Patients with mild illness do not usually need to be treated with antibiotics. However, for prolonged or severe illnesses, such as with V. vulnificus infection, treatment with the appropriate antibiotics should be considered and initiated promptly to improve survival.
Patients should also be asked to recall all seafood and water exposures during the seven days prior to illness onset. This information may help public health investigators solve outbreaks.
Patients whose occupation or recreational activities expose them to potentially contaminated sources (e.g., warm, salty marine environments and shellfish) should be educated on the ongoing risk of vibriosis.

Reporting

Healthcare providers are required to report cases of vibriosis to the local health department (LHD) within one working day of identification or immediately by telephone if an outbreak is suspected. In addition, LHDs may need to restrict the activities of persons with vibriosis from certain work or activities (such as food handling, health care, or day care) until their symptoms have resolved.