Public Health Notice: Outbreak of Vibrio parahaemolyticus infections linked to shellfish

On this page

• Why you should take note
• What is Vibrio
• Investigation summary
• Who is most at risk
• What you can do to protect your health
• Symptoms
• What the Government of Canada is doing
• Epidemiological information
• Additional information
• Media contact
• Public enquiries
• Investigation history

Why you should take note

The Public Health Agency of Canada (PHAC) collaborated with provincial and territorial public health and food safety partners to investigate an outbreak of Vibrio parahaemolyticus infections that occurred in four provinces. The outbreak appears to be over and the investigation is winding down.

Investigation findings identified exposure to shellfish as a likely source of the outbreak. The majority of the individuals who became sick reported eating shellfish, mainly raw oysters, harvested from Atlantic Canadian coastal waters, before their illnesses occurred.

Although the outbreak appears to be over, this event is a reminder that you can get sick from eating raw or undercooked shellfish, especially oysters. To prevent the risk of illness, shellfish should be cooked thoroughly to a safe internal temperature of 74°C (165°F) before eating or serving it.

This notice contains more advice on how to avoid getting sick.

What is Vibrio

Vibrio is a naturally-occurring bacterium that can be present at high levels in coastal waters during periods of increased water temperatures. Most people come in contact with Vibrio by eating raw or undercooked shellfish, especially oysters.

Investigation summary

In total, 23 confirmed cases of Vibrio parahaemolyticus illness were reported in the following provinces: Saskatchewan (1), Quebec (7), New Brunswick (10), and Prince Edward Island (5). Individuals became sick between early July and late October 2020. One individual was hospitalized. No deaths were reported. Individuals who became ill were between 11 and 92 years of age. The majority of illnesses (61%) were male.

Who is most at risk

People most at risk for complications are pregnant women, people with weakened immune systems, liver disease and low stomach acidity, young children and the elderly. These individuals should not eat raw or undercooked shellfish.

Most people recover fully within a week. It is possible for some people to be infected with Vibrio and to not get sick or show any symptoms, but to still be able to spread the infection to others. People can also pass on the bacteria to others through infected stool.

What you can do to protect your health

It is difficult to know whether a shellfish product is contaminated with Vibrio because you can't see, smell or taste it. The following tips may help reduce your risk of getting sick from Vibrio, but they may not fully eliminate the risk of illness.

• Avoid eating raw or undercooked shellfish.
• Get your shellfish products from a licensed establishment or harvest them from a fishing area which is open under the Canadian Shellfish Sanitation Program (CSSP), Fisheries and Oceans Canada.
• Store and transport shellfish at 4ºC (39ºF) in the refrigerator or on ice from the time purchased until cooking or eating.
• Shellfish must be cooked to a safe internal temperature of 74ºC (165ºF) to kill bacteria like Vibrio.
• Follow proper safe food handling practises when preparing and cooking shellfish:
  • Wash your hands for 20 seconds with soap and warm water before and after handling any shellfish.
  • Always clean and properly sanitize any cutting boards, counters, kitchen surfaces, knives and other utensils used to prepare raw shellfish.
  • Use only drinking-quality water for rinsing shellfish.
  • Discard any shellfish that do not open when cooked.
  • Eat shellfish right away after cooking and refrigerate leftovers.
  • Always keep raw and cooked shellfish separate.
  • Wear protective clothing (like gloves) when handling raw shellfish.
  • Avoid exposing open wounds or broken skin to warm salt or brackish water, or to raw shellfish.
• Avoid taking antacids prior to eating oysters, or other seafood, as reduced stomach acid may favour the survival and growth of Vibrio.
• If you have been diagnosed with a Vibrio infection or any other gastrointestinal illness, do not cook food for other people.
• Contact your local public health authority to report any food safety concerns at restaurants, grocery stores, or if you suspect food poisoning from a restaurant or other food establishments.

Symptoms

People infected with Vibrio can experience a wide range of symptoms. Some do not get sick at all, while others feel as though they have a bad case of stomach flu. Few people get seriously ill.

Most people develop one or more of the following symptoms 12 to 24 hours after being infected with the bacteria:

• watery or bloody diarrhea
• stomach cramps
• nausea
• vomiting
• fever
• headache
• chills
• abnormally low blood pressure
• bacteria present in the blood

The illness can last up to three days, and severe illness is rare. Patients should drink plenty of liquids to replace fluids lost through diarrhea. People who experience symptoms, or who have underlying medical conditions, should contact their health care provider if they suspect they have a Vibrio infection.

What is the Government of Canada doing

The Government of Canada is committed to protecting the health of Canadians from enteric disease outbreaks.

The Public Health Agency of Canada leads the human health investigation into an outbreak and is in regular contact with its federal, provincial and territorial partners to monitor the situation and to collaborate on steps to address an outbreak.

Health Canada provides food-related health risk assessments to determine whether the presence of a certain substance or microorganism poses a health risk to consumers.

The Canadian Food Inspection Agency conducts food safety investigations into the possible food source of an outbreak. They also monitor for biotoxins in shellfish in harvesting areas and are responsible for registering and inspecting fish and shellfish processing plants.

Fisheries and Oceans Canada is responsible for opening and closing shellfish harvest areas, and enforcing closures under the authority of the Fisheries Act and the Management of Contaminated Fishery Regulations.

The Government of Canada will continue to update Canadians if new information related to this investigation becomes available.

Epidemiological information

Figure 1 is an epidemiological curve for this outbreak, which shows the numbers of new cases by month. Outbreak investigators use this information to show when illnesses begin, when they peak and when they trail off. It can take several weeks from the time a person becomes ill to when the illness is reported and testing confirms a link to the outbreak. Data are available for 23 cases.

Figure 1 - Text description

Table 1 – Number of people confirmed to be infected with Vibrio parahaemolyticus by week of illness onset or specimen collection

Week of symptom onset or specimen collection	Number of cases
2020-06-28	1
2020-07-05	0
2020-07-12	0
2020-07-19	0
2020-07-26	1
2020-08-02	2
2020-08-09	2
2020-08-16	4
2020-08-23	3
2020-08-30	2
2020-09-06	5
2020-09-13	2
2020-09-20	0
2020-10-04	0
2020-10-11	0
2020-10-18	0
2020-10-25	0
2020-11-01	1

Additional information

• Vibrio
• Shellfish food safety
• Safe cooking temperatures
• Storing, handling, and cooking shellfish
• COVID-19 and food safety

Media contact

Public Health Agency of Canada
Media Relations
613-957-2983

Public enquiries

Call toll-free: 1-866-225-0709
Email: info@hc-sc.gc.ca

Investigation history

Public Health Notice: October 14, 2020

Why you should take note

The Public Health Agency of Canada (PHAC) is collaborating with provincial and territorial public health and food safety partners to investigate an outbreak of Vibrio parahaemolyticus infections occurring in four provinces.

Based on the investigation findings to date, exposure to shellfish has been identified as a likely source of the outbreak. Many individuals who became sick reported eating shellfish, mainly raw oysters, harvested from eastern coastal waters, before their illnesses occurred. More information is needed to determine the supply source and distribution of these oysters. The outbreak investigation is ongoing as illnesses continue to be reported to PHAC.

This outbreak is a reminder that you can get sick from eating raw or undercooked shellfish, especially oysters. To prevent the risk of illness, shellfish should be cooked thoroughly to a safe internal temperature of 74°C (165°F) before eating or serving it. This notice contains more advice on how to avoid getting sick.

This public health notice will be updated as the investigation evolves.

Investigation summary

As of October 14, 2020, there are 21 confirmed cases of Vibrio parahaemolyticus illness in the following provinces: Saskatchewan (1), Quebec (7), New Brunswick (10), and Prince Edward Island (3). Individuals became sick between early July and mid-September 2020. One individual has been hospitalized. No deaths have been reported. Individuals who became ill are between 11 and 92 years of age. The majority of illnesses (63%) are male.

It is possible that more recent illnesses may be reported in the outbreak because there is a period of time between when a person becomes ill and when the illness is reported to public health officials. For this outbreak, the illness reporting period is between nine and twelve weeks.