Public health authorities in Washington state say they have pinned down the origin of a listeria outbreak that led to six hospitalizations and the deaths of three people: contaminated milkshakes.
Investigators with the Washington State Department of Health found listeria bacteria in “all milkshake flavors” sold at a Frugals brand restaurant in Tacoma. The culprit behind the contamination were two ice cream machines that hadn’t been cleaned properly.
Two of the people who were hospitalized with listeria reported that they had consumed milkshakes at the Frugals burger restaurant prior to falling ill.
Health authorities said that milkshakes and ice cream had caused listeria outbreaks in the past, so health inspectors collected milkshake samples on Aug. 8 for testing. A week later, genetic fingerprinting of the bacteria in the milkshakes showed it was the same strain of listeria that caused the outbreak.
The six victims were all hospitalized between Feb. 27 and July 22, but health officials are still warning the public to contact their doctors if they consumed milkshakes at the Tacoma Frugals location during the summer, since listeria infections can take up to 70 days to present symptoms.
No other Frugals locations are believed to be affected in the listeria outbreak.
The restaurant discontinued the use of its two ice cream machines on Aug. 8 and they will be kept out of service until the the Tacoma-Pierce County Health Department determines they are free of listeria contamination.
The six who were hospitalized all had conditions that weakened their immune systems, making it harder for their bodies to fight off the infection. The victims were between the ages of 40 and 79.
Most people who eat food contaminated with listeria do not get seriously sick, but people who are pregnant, immunocompromised, or over the age of 65 may be more susceptible to listeria infections.
Symptoms of listeria infection, or listeriosis, include fever, muscle aches and tiredness. People may also experience headaches, stiff necks, confusion, loss of balance and seizures, Washington health officials said. Symptoms usually arise within two weeks of infection.
Listeriosis can also cause pregnancy loss, premature birth and serious illness or death in newborns.
Frugals Tacoma posted a statement on its Instagram page Saturday, a day after health officials announced the origin of the outbreak.
The chain said it was “deeply saddened” to learn that six people were hospitalized and three later died after eating at the restaurant.
“We are heartbroken and deeply regret any harm our actions could have caused,” the statement reads.
The burger chain said it will continue to comply with the health investigation and confirmed it sent its milkshake equipment to an independent facility for cleaning and sanitation before it is re-tested for bacteria.
“Out of an abundance of caution for our customers, we have also directed all milkshake machines in our other locations to be shut down and samples from these machines to be sent out for similar testing,” Frugals said.
“As a family-owned business for over 30 years, the trust of our customers is paramount,” the restaurant said. “We will continue to fully cooperate with this investigation, and we are committed to making any changes deemed necessary to maintain our high standard of operations and prevent this from happening again.”
According to Health Canada, listeria bacteria are widespread in the natural environment, in soil, vegetation, water, livestock feed, and the feces of humans and animals. Farm animals that appear healthy can carry listeria and contaminate meats and dairy products.
Unlike most bacteria, listeria can survive and even grow on foods stored in a refrigerator.
“Moreover, foods that are contaminated with this bacteria look, smell and taste normal,” Health Canada states.
With proper cooking and pasteurization techniques, listeria can be killed.
Listeria infections are considered quite rare in Canada. In recent years, just over 130 cases of listeria infections are reported annually.
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