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December 22, 2020

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  • Consider Shigella infection in patients with compatible signs and symptoms, especially among people experiencing homelessness or unstable housing, including diarrhea which may be watery or bloody, fever, and abdominal pain.
  • Order stool culture and antimicrobial susceptibility testing (AST) for patients suspected of having Shigella. Culture-independent diagnostic testing on its own (e.g., PCR) cannot be used to assess susceptibility.
    • If the AST includes minimum inhibitory concentration (MIC), avoid prescribing fluoroquinolones for ciprofloxacin MICs in the 0.12–1.0 μg/mL range based on CDC recommendations in resources below.
  • Although antibiotic therapy is not routinely recommended for mild infections, it should be prescribed for patients with more severe illnesses and when there is elevated concern about transmission to others (e.g., in congregate living situations) and in outbreak settings (consult with Public Health).
  • Gather information about risk factors (exposure period is typically 1-7 days before symptom onset) including travel history, housing situation, sexual history and potential exposed contacts.
    • Please document if the patient is experiencing homelessness and if so, where they stay at night and where they receive food (shelters, food banks, temporary housing programs, street/encampments, etc.).
  • Counsel patients with diarrhea on how they can prevent spreading the infection to others:
    • Wash hands with soap and water for at least 20 seconds, especially after using the toilet, after handling a soiled diaper, and before eating or preparing food; avoid preparing food for others.
    • Wait to have sex (vaginal, anal and oral) for at least one week (several weeks is preferable) after diarrhea has resolved because Shigella may still be in stool for several weeks.
    • People with Shigella should be excluded from food handling, childcare settings and patient care until follow-up is completed by Public Health.
    • Children with active diarrhea should not attend childcare, school, or group activities while ill.
  • Ensure laboratories send all specimens to the WA State Public Health Lab in Shoreline for confirmatory testing: best specimens include isolates and stool/swab in transport medium.
  • Report suspected or confirmed cases of shigellosis to Public Health at (206) 296-4774.

Public Health is investigating a total of 31 cases of Shigella infection reported since October 22, 2020, with 18 of them reported in the last 7 days. Of the 31 cases, 24 appear to be among people experiencing homelessness or unstable housing; all 24 are adults and 21 (88%) are male. Of these 24 cases, 23 (96%) have been hospitalized as compared to only 2 of 7 (29%) stably housed cases during this same time frame. Preliminary lab testing has identified S. flexneri in some of these cases. Further confirmatory lab testing is pending at WA Public Health Lab, including serotyping and whole genome sequencing.

No specific location has been linked to the recent infections at this time. Interview data suggests patients are staying at various shelters, on the street, and in tents around the Seattle area. Patients also report a variety of food sources including but not limited to food banks, day centers, other homeless service sites, and food from the street.

Shigella is easily spread person-to-person through the fecal-oral route and through sexual contact, especially in situations with limited access to hygiene facilities. Persons at higher risk of Shigella infection include men who have sex with men, people whose immune systems are weakened due to illness such as HIV or medical treatment such as chemotherapy, young children, and travelers to developing countries. People with weakened immune systems are also more likely to develop serious illness, including bacteremia.