Vancouver, Toronto, and Edmonton have all had outbreaks of infectious diarrhea lately, many of them caused by infections with Shigella species. One of the most common causes of dysentery, Shigella infections, cause gastrointestinal symptoms including severe diarrhea, and are easily transmissible in the absence of proper sanitation. Since people experiencing homelessness don’t always have access to toilets and clean living conditions, they are at a much higher risk of contracting and spreading the infection.
Annually, more than 160 million people contract Shigella infections worldwide, leading to 1.1 million deaths. The vast majority of those cases (more than 99%) occur in developing countries whose citizens lack access to clean water and proper sanitation. As few as 10 Shigella organisms can lead to gastrointestinal infection, making effective cleaning exceptionally important. If not disinfected, Shigella can remain infective for five or more days on a dry surface, and up to 40 days in water, depending on temperature. 1 Fortunately, Shigella infections tend to remain localized to the gastrointestinal tract, and only rarely pass to the blood-stream. 1
Depending on the species and serotype, Shigella infections typically have a hospitalization rate of between 20 and 34%. 1 However, of the 447 patients identified by Alberta Health Services to be infected with Shigella since August 2022, 309 were hospitalized, 2 meaning patients were hospitalized at more than double the typical rate.
Cases of diarrhea caused by Shigella infections spike in the winter in Canada as unhoused populations spend more time together indoors. Malnutrition can increase the likelihood of becoming infected with Shigella, which puts those experiencing homelessness at even further risk. 2
In Canada, 2.2% of households find themselves on the streets at some point in their lives, while 10.5% experience “hidden homelessness”, relying on friends or family to take them in when they lose their home. As financial pressures on Canadians continue to increase, it’s easy to imagine that rates of homelessness will rise as well, unless swift action is taken to prevent it. According to Statistics Canada, 41.8% of unhoused people reported that financial issues were there the primary reason for losing their home. In the fall of 2022, 44% of Canadians were very concerned with their household’s ability to afford rent. In BC in particular, a recent Ipsos poll found that 46% of British Columbians surveyed are $200 away from not being able to pay their bills, and a full third are already behind. 3
In 2023, BC’s Guidelines and Protocols Advisory Committee (BC GPAC) released guidelines for the testing of infectious diarrhea with a new infectious diarrhea panel. This approach calls for laboratories to screen for the presence of the 14 most common diarrhea-causing pathogens, including bacteria, viruses, and parasites using molecular, multiplex tests. This testing is faster, more sensitive, and requires the acquisition of fewer stool samples than conventional culture methods of detection.
In response to this new requirement for BC and anticipating other provinces to move towards this kind of testing, CMPT provides a Gastrointestinal Panel PT program which challenges all 14 species listed in the BC guidelines, for labs that perform this kind of testing.
1. Humphries, RM, Faron ML, Dekker JP, Ledeboer NA, Buchan BW. Escherichia and Shigella,. In: Carrol K. C. et al, ed. Manual of Clinical Microbiology. Vol 2. 13th ed. ASM; 2023:760.
2. https://www.cbc.ca/news/health/shigella-infection-canada-1.7437238 – Accessed February 12, 2025
3. https://www.cbc.ca/news/canada/british-columbia/rising-housing-and-debt-challenges-bc-1.7431122 – Accessed February 12, 2025
