Public health priority: High for clusters and higher priority species. Routine for everything else
PHUS response time: Respond to suspected clusters and higher priority cases within 1 working day of notification/detection. Enter confirmed cases on NCIMS within 1 working day. Follow-up of routine cases is at the discretion of the relevant public health unit.
Case management: Determine possible exposures
Contact management: Education
Roles and responsibilities:
Only confirmed cases should be notified
Confirmed case
A confirmed case requires laboratory definitive evidence only
Laboratory definitive evidence
Isolation or molecular detection of Vibrio species (note that toxigenic Vibrio cholerae O1 or O139 are notified separately under Cholera) from an appropriate clinical specimen.
Appropriate clinical specimens include stool, sterile site samples including blood, and deep wound swabs. Skin and ear swabs would not meet this definition.
Factors to be considered in case identification
Laboratory diagnosis of vibriosis involves detection or isolation of Vibrio species from a clinical specimen. Special media are required for culture.
Vibriosis is to be notified by diagnostic laboratories on microbiological confirmation.
Further information on notification requirements can be found online: NSW Health disease notification procedures.
Only confirmed cases should be entered into NCIMS.
Infectious agent
There are many different species of the Vibrio bacteria that cause human disease. Different Vibrio species commonly coexist in the same aquatic environments.
Table 1: Most important Vibrio spp causing human infections (Adapted from Baker-Austin et al. Nature Reviews-Disease Primers 2018)
Clinical manifestation/disease severity
Gastrointestinal vibriosis is most commonly transmitted by eating contaminated raw or undercooked seafood, especially shellfish. Infection can also occur when the Vibrio bacteria enter the body through a break in the skin while a person is in salt or brackish water. Vibrio species can also cause ear infections when this water enters a person’s ear. Person-to-person transmission of Vibrio bacteria is rare, but more common within households.
The time between exposure and onset of symptoms varies with infection type (e.g., gastrointestinal, infected wound, systemic infection with bacteraemia) and Vibrio species. Symptoms of gastrointestinal infection with most Vibrio species can appear anywhere from 4–96 hours after eating raw or undercooked seafood but usually appear within 12–24 hours after exposure. Gastrointestinal symptoms last around 3 days (range 8 hours to 12 days). Symptoms of wound infection might appear as few as four hours after exposure, and symptoms of blood infection usually appear within four days of exposure.
Symptoms of vibriosis can vary depending on the species and site of infection. Common symptoms include watery diarrhea, stomach cramps, vomiting, fever, chills. Ear and wound infections often appear red, swollen and painful. Symptoms usually appear within 12-24 hours and can last 1-7 days. Most people infected with vibriosis will recover on their own; however, people with underlying health conditions or weakened immune systems, such as the elderly, may developing life-threating illness resulting in hospitalisation or death.
Vibrio species can grow on a wide variety of bacteriological media including blood agar, MacConkey agar, Hektoen (HE) agar, Xylose Lysine Deoxycholate (XLD) agar and specialised selective/differential media for Vibrio species, such as thiosulphate citrate bile salt (TCBS) agar. In NSW, laboratories do not routinely use specialised media for Vibrio species, unless the Vibrio culture is requested by the treating clinician, or by some laboratories if there is suspicion that the patient has vibriosis. A presumptive identification of the Vibrio species can be made from growth on differential media such as TCBS but will require confirmation using additional laboratory tests.
Vibrio bacteria can also be detected using nucleic acid tests (NAT) by laboratories that use gastrointestinal pathogen multiplex assays containing Vibrio species as one of the targets. A culture of the isolate from the primary sample will be required to identify the Vibrio species detected by the NAT and to differentiate between vibriosis and cholera. It is important to note that the NAT cannot discriminate between live and dead bacteria present in the sample.
Investigation
Begin follow-up investigation within one day of notification for:
Vibrio vulnificus can lead to severe clinical outcomes and have a high fatality rate, particularly among vulnerable populations. As such, individual case follow up may be beneficial to assess whether there is ongoing risk to other vulnerable people (e.g. in the environment, or from the same exposure source) and whether any further public health action is warranted. This is at the discretion of the PHU director.
Investigations of outbreaks will follow the control guidelines for managements of suspected foodborne outbreaks.
Data Entry
The following data needs to be entered into NCIMS for each case that is followed up.
The response to a notification will normally be carried out in collaboration with the case's health carers. For cases where the PHU undertakes follow-up, PHU staff should ensure that action has been taken to:
Treatment is managed of the diagnosing doctor.
Cases that are followed up should have their overseas travel ascertained for the exposure period (7-days before onset of illness), including the countries visited. For cases with most of their exposure in Australia, shellfish and environmental exposures should be collected as per the questionnaire.
Refer to Therapeutic Guidelines. Antibiotics are generally not recommended to treat mild Vibrio infections. People with diarrhea or vomiting should drink plenty of liquids to prevent dehydration. Antibiotics may be used to treat severe or prolonged Vibrio infections. Vibrio wound infection is treated with antibiotics and surgery to remove dead or infected tissue.
Inform the case or relevant caregiver about the nature of the infection and the mode of transmission. Emphasise the importance of hygiene practices, particularly handwashing before eating, preparing food, and after using the toilet. See factsheet
Cases who are food handlers or carers for young children, the elderly or vulnerable persons should be advised not to attend work until 48 hours after the resolution of symptoms. Children in childcare should not attend until 24 hours after diarrhoea has stopped.
For single cases, contact management is not required. However, if other people in the household (or household like situation) are also unwell with diarrhoea they should be encouraged to be investigated for vibriosis and be excluded from food handling and care of children or patients until at least 48 hours after diarrhoea has ceased.
Baker-Austin C, Oliver JD, Alam M, et al. Vibrio spp. Infections. Nature Reviews – Disease Primers 2018; 4(1):8.
Brehm TT, Berneking L, Martins MS, et al. Heatwave-associated Vibrio infections in Germany, 2018 and 2019. Euro Surveillance 2021;26(41):pii-2002041.
Leong L, et al. An outbreak of Vibrio parahaemolyticus food poisoning associated with consumption of oysters, Australia, 2021-2022. Emerging Infectious Diseases 2024.