23/06/19: Increase in vibrio illnesses prompts warning in New Zealand

New Zealand Food Safety did not say how many people had been affected but reported an increase in people with food poisoning caused by Vibrio parahaemolyticus during the past six weeks.

Vibrio parahaemolyticus is a marine microorganism that occurs naturally worldwide. Not all strains cause illness in humans and surveys so far of New Zealand shellfish have found very low levels and incidence of disease-causing strains.

Patients ate raw or partially cooked mussels

Symptoms are predominantly stomach cramps and watery diarrhea and sometimes nausea, vomiting, and fever. Generally, people who are sick recover without hospital treatment, however, in severe cases hospitalization is required. New Zealand Food Safety advises consumers who are pregnant or have low immunity to avoid eating raw shellfish.

Paul Dansted, New Zealand Food Safety’s director of food regulation, said most people who became sick bought commercially-grown New Zealand mussels harvested from one growing area in the Coromandel and ate them raw or partially cooked.

“Additional testing is being done to confirm the type of Vibrio parahaemolyticus that has caused this illness. It is possible that the strain of Vibrio parahaemolyticus is unusually aggressive which may mean that even low numbers could cause illness. Additional testing of mussels and the waters that they are being grown in is also underway to help us understand why this has happened,” he said.

“The mussels at the center of the outbreak were all bought in their raw state, in the shell. They are not the mussels that can be bought in plastic bottles. Those mussels are cooked and marinated and are not affected. Until we have more information, New Zealand Food Safety is reminding people to take care when handling, preparing and consuming mussels.”

The growing area has been closed by New Zealand Food Safety while investigations continue.

New Zealand Food Safety advice includes:

  • Cooking temperatures for mussels should be above 65 degrees Celsius to ensure any Vibrio parahaemolyticus that is present will be destroyed.
  • Don’t eat raw or undercooked mussels or other shellfish
  • Always wash hands with soap and water after handling raw shellfish
  • Avoid contaminating cooked shellfish with raw shellfish and its juices

Campylobacter limit review

Meanwhile, the Ministry for Primary Industries (MPI) is reviewing regulatory limits for Campylobacter that apply to chickens for poultry operators.

There are three regulatory limits for Campylobacter in the Poultry National Microbiological Database Programme.

The Campylobacter performance target comprises the enumeration target; detection target; and prevalence performance target that only applies to standard throughput operators of meat chickens.

Options include maintaining the system as it is now, requiring reduced detections, removing the prevalence performance target, requiring a tighter enumeration target or amending reset of the non-compliant moving window. The preferred approach is a combination of these options.

“It is expected that lowering of all the targets (enumeration, detection and prevalence performance target) to some degree will prompt further actions by industry to reduce the levels of Campylobacter, and achieve nil detections of Campylobacter in a much more significant number of the total chickens processed in New Zealand,” according to New Zealand Food Safety.

MPI received a proposal to amend the Campylobacter regulatory limits from the Poultry Industry Association of New Zealand (PIANZ) in November 2018.

At the end of 2017, the total of notified campylobacteriosis cases was 6,482 and 3,771 are estimated to be foodborne. Attribution studies published in 2017 show that whilst there are other potential sources of foodborne Campylobacter such as raw drinking milk, poultry meat continues to be a significant source of human cases in New Zealand.