Fraser Health observed a surge in confirmed Shigella cases in January 2026, especially among people experiencing housing insecurity (i.e. having no fixed address or living in a shelter at the time of illness).
Unlike previous surges such as the one in the winter and spring months of 2023–2024, which were predominantly driven by S. sonnei, the January 2026 increase was characterized by an increase of S. flexneri (61 per cent of isolates), mainly a multidrug-resistant strain of S. flexneri serotype 2a. This has implications for clinical testing and treatment. Please check the testing and treatment sections below for more details.
Multidrug-resistant (MDR) Shigella are strains that are resistant to three or more of the five established antibiotics used to treat Shigella infections (azithromycin, fluroquinolones (e.g. ciprofloxacin), third-generation cephalosporins (e.g. ceftriaxone), TMP-SMX and ampicillin). In recent years, MDR Shigella have emerged across B.C. Some individuals have required intravenous (IV) antibiotic therapy due to resistance to most or all oral agents. In Fraser health, 46 per cent of all the Shigella isolates obtained from cases in January 2026 were classified as MDR.
Shigella spreads fastest in environments where access to sanitation and hygiene is limited. In the past several years, outbreaks of Shigella infections among underhoused populations have been noted in Alberta, Ontario and some parts of B.C. In Fraser Health, 46 per cent of Shigella cases reported in January 2026 occurred in people experiencing housing insecurity. Among these individuals, MDR isolates accounted for 62 per cent of cases, compared with 33 per cent among those who were not experiencing housing insecurity. One caveat is that 13 per cent of isolates from individuals not experiencing housing insecurity could not have MDR status determined because of data limitations.
Clinical presentation: Shigella cases most often present with diarrhea accompanied by fever, nausea and tenesmus. The diarrhea caused by Shigella may be bloody, mucoid or watery. Bacteremia may occur but is uncommon. Severity varies with host factors (age, nutritional status and immune function) and with serotype. Mild infections are usually self-limited, lasting on average four to seven days.
Transmission: Shigella is spread via the fecal-oral route. Transmission can occur through ingestion of contaminated foods or water, touching contaminated objects or from engaging in certain sexual practices. Given the low infectious dose of 10-100 organisms, meticulous hand hygiene is essential in preventing transmission.
Diagnosis and testing: Diagnostic work-up of acute diarrhea depends on suspected etiology, duration of diarrhea, symptom severity and patient factors.
Please consider Shigellosis and order an Infectious Diarrhea Panel (IDP) for patients presenting with gastroenteritis AND any one of the following:
- Prolonged mild to moderate symptoms > seven days.
- Severe symptoms (e.g. bloody stools).
- Patient is severely immunocompromised (e.g. cancer, transplant recipients, untreated HIV).
- Patient is experiencing housing insecurity.
An IDP includes testing for viral, protozoal and bacterial causes including Shigella. When applicable, antimicrobial susceptibilities are provided.
In patients with severe Shigellosis who require hospital admission, please consider blood cultures.
Treatment:
- Individuals who are immunocompetent and are experiencing mild symptoms do not require antibiotics and should be managed supportively.
- Adults who test positive on Shigella/Enteroinvasive Escherichia coli (EIEC) PCR (included in IDP) and who are either immunocompromised or experiencing moderate to severe symptoms should be empirically treated with IM or IV Ceftriaxone 1g daily for three to five days.
- Patients experiencing housing insecurity who are at an increased risk for decompensation in the community (i.e. experiencing barriers to treatment or having medical comorbidities) should also be considered for empiric treatment.
- Clinics that are unable to offer IM/IV Ceftriaxone should refer patients for outpatient parenteral therapy.
- Due to circulation of MDR Shigella, oral antibiotic treatment should be guided by culture and susceptibility results whenever these are available.
Education and counselling:
- All individuals should be advised to stay hydrated during their illness.
- Advise to practice good hand hygiene, particularly after using the washroom, and before eating or preparing food or drinks.
- Soiled laundry should be laundered separately whenever feasible.
It is recognized that people experiencing housing insecurity may find it difficult to follow these recommendations due to limited or inconsistent access to washrooms and laundry facilities.
Public Health management of cases and contacts: Shigellosis is a reportable disease in B.C. Reporting of a positive Shigella result is done by the laboratories directly to Fraser Health Public Health. Upon receipt of notification, Public Health will conduct case interview and contact tracing where possible (i.e. if cases can be contacted), not only to determine where the client acquired the illness but to also prevent further transmission by providing Public Health intervention as necessary.
Due to the recent increase of Shigella cases among people experiencing housing insecurity in the Fraser Health region, if you become aware of a cluster of gastroenteritis suspicious for Shigella infection in a congregate living setting such as a shelter or single-room supportive housing, please contact Fraser Health Public Health at 1-866-990-9941 (Select Option two).