October 5, 2018
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Re: Listeriosis outbreak
An outbreak investigation is underway for four Listeria monocytogenes cases in Ontario that are linked by molecular testing. Of the cases with available information, all three reported eating at the Druxy’s Famous Deli located in the Princess Margaret Cancer Centre (610 University Avenue) in Toronto. The molecular fingerprint of the cases in this outbreak is the same or closely related to that of three cases from an outbreak in March 2018, which was also linked to that Druxy’s location.
The purpose of this communication is to provide information about listeriosis to support prompt diagnosis and treatment of infected patients.
What is listeriosis?
Listeriosis is an infection caused by the bacteria Listeria monocytogenes. A person with listeriosis usually has fever, muscle aches, diarrhea, and sometimes, nausea and vomiting. Infection may lead to meningoencephalitis that can be sudden in onset.
Complications include septicemia, endocarditis, and internal and external abscesses. Infected pregnant women may experience minimal symptoms, characterized by a mild flu-like illness. An infected pregnant woman may unknowingly pass on the illness to the fetus. Infection during pregnancy may lead to spontaneous abortion, premature birth, stillbirth, or neonatal infection.
How is listeriosis infection acquired?
People are infected by ingesting contaminated food such as ready-to-eat meats (e.g. deli meats), unpasteurized milk and soft cheeses, and raw vegetables.
Implications for health care providers
In light of this outbreak, a history of consuming food from the Druxy’s location at Princess Margaret Cancer Centre increases the possibility of listeriosis in those with compatible signs and symptoms.
Further information about the clinical presentation of listeriosis can be found on the following websites:
- Government of Canada: https://www.canada.ca/en/publichealth/services/diseases/listeriosis/health-professionals-listeriosis.html
- United States Centers for Disease Control and Prevention: https://www.cdc.gov/listeria/technical.html
Should you suspect listeriosis in your patient, please contact Public Health Sudbury & Districts immediately by calling 705.522.9200.
Listeria testing information
- Prompt diagnosis using two sets of blood cultures is recommended for those with exposure to potentially implicated foods (e.g. food from the Princess Margaret Cancer Centre’s Druxy’s location prior to its closure on September 26, 2018) who present with symptoms of invasive listeriosis infection or gastroenteritis and fever. The incubation period for invasive listeriosis is generally 2 to 3 weeks, but can range from 3 to 70 days.
- Testing of asymptomatic individuals who consumed food from the Princess Margaret Cancer Centre’s Druxy’s location is not recommended. These individuals should be advised to promptly return for care if symptoms develop within 70 days of their last exposure. Testing of those who had symptoms that have now fully resolved is also not recommended. However, these individuals should be advised to return for care if symptoms develop within 70 days of their last exposure.
- Stool testing and serology for Listeria is not recommended, although individuals with gastroenteritis can have stool testing for other pathogens as per routine practice
More detailed information regarding Listeriosis and testing procedures can be found on the Public Health Ontario Website:
Ariella Zbar, MD, CCFP, MPH, MBA, FRCPC
Associate Medical Officer of Health and Director, Clinical Services
This item was last modified on October 23, 2018