Shigella outbreak hits Calgary shelters and encampments, sending 16 to hospital

An outbreak of a highly infectious gastrointestinal illness is impacting Calgary's homeless population and is responsible for more than a dozen hospitalizations so far.

Shigella infections can be severe, and health officials are working to curb transmission in shelters and encampments.

According to Alberta Health Services, 63 people have tested positive for shigella since the outbreak was declared on June 5.

There have been 28 hospitalizations linked to the outbreak, AHS said, including 16 people who required hospitalization as a direct result of the illness and 12 who tested positive while in hospital for other medical reasons. No deaths have been reported.

"The focus started off in shelter settings but we are now picking up more cases among people who are sleeping rough," said Dr. David Klassen, a medical officer of health with Alberta Health Services in the Calgary zone.

Symptoms of shigella infection include diarrhea (often bloody), abdominal cramps, fever and vomiting. 

While most people recover on their own, serious complications can occur, including severe dehydration and bloodstream infections. 

The bacteria can spread through fecal-oral transmission, meaning the illness spreads quite easily when someone doesn't wash their hands properly after going to the washroom. People can get sick in a number of ways, including after touching contaminated surfaces and eating contaminated food.

"Even really small amounts of the bacteria can cause illness in those other people. That's why we care about it so much … it's so easily spread around and there's a possibility of severe illness," said Klassen.

Transmission can be difficult to control in crowded or unsanitary conditions.

"Folks in this population are often needing to congregate in larger groups to have their basic needs met, to access food, to access shelter. And so that's why we see it spread in this population more readily," said Klassen.

"It's just challenges with meeting basic hygiene needs and with people more likely coming into group settings." 

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According to Klassen, environmental public health inspectors are working with shelters to control the spread through more frequent inspections. AHS is providing guidance on symptom screening, testing referrals and increased disinfection.

Klassen said AHS is also working with agencies that support people living in encampments.

Alpha House is distributing personal hygiene kits (including water, hand sanitizer, wipes and garbage bags) to people with symptoms in those settings. Adult diapers are also available for those who need them.

"I'm very worried," said Patty Wilson, a nurse practitioner who works with vulnerable Calgarians.

"Many of the folks that are impacted don't have a bed to lie down on, tap water to drink and replenish themselves, [or] regular food."

Wilson is concerned about the number of people who've been hospitalized due to the illness.

"It's very high with shigella because it's so difficult to contain and properly address when we are lacking those hygiene facilities.… We don't need another stressor on our health-care system right now."

She's calling for additional steps to be taken, including bringing in more public washrooms and hygiene facilities for people experiencing homelessness.

"It's a disease that's very common in disaster areas — where people do not have regular access to running water, bathrooms, those very basic hygiene facilities that many of us take for granted."

Edmonton outbreak continues

An ongoing shigella outbreak in Edmonton has led to 424 cases of shigella, including 294 hospitalizations since it began in 2022.

An outbreak was recently declared in the central zone — in  the Maskwacis area — as well.

A spokesperson for Indigenous Services Canada (ISC) confirmed it has been helping Maskwacis Health Services deal with a "limited shigella outbreak," including supports with contact tracing, testing, treatment and prevention efforts.

No connections have been identified between the Maskwacis outbreak and the one in Calgary, according to the statement.

Neither AHS nor ISC provided case numbers for this outbreak.

"There have been increasing outbreaks of shigella described across North America over the last years," said Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta.

"The fact that it's occurring in a lot of inner-city populations and other crowded circumstances is, in a way, a negative sign of the times to me." 

There are four species of shigella and, according to AHS, Calgary's cases are caused by shigella sonnei, while Edmonton's are caused by shigella flexnari.

"We're not seeing really severe illness and any bad outcomes in our outbreaks, and there's no one currently hospitalized," said Klassen.

Meanwhile, the sheer number of  hospitalizations in both Edmonton and Calgary are a worry for Saxinger.

"To me, that suggests there's a whole bunch of cases that we're not picking up at all that are still out there," she said.

According to Saxinger, the inability to contain the outbreak in Edmonton may not bode well for Calgary.

"It could basically become another long-standing epidemic in Calgary unless they're able to really get all over it and change the situation that's causing the risk, which is people living in unsafe, unhygienic circumstances."