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shigella

Shigella Infection (Shigellosis)

What is Shigella Infection?

Shigella is a type of bacteria (germ) that can make people sick with diarrhea (sometimes bloody), fever, and stomach pain. It usually starts 1-2 days after someone is exposed and lasts about a week. Most people with shigellosis recover completely; however, a small number of people can develop more serious complications, including arthritis, kidney failure, bloodstream infections, and seizures.

Current Situation

Los Angeles County (LAC) has seen an increase in Shigella cases since 2022. Since 2017, LAC has also seen an increase in cases of multi-drug and extensively drug resistant shigellosis particularly affecting men who have sex with men (MSM). In 2018, the CDC released a health alert regarding the increase in multi-drug resistant Shigella outlining clinical guidance available HERE.

Recent Updates
  • June 5, 2025: Increase in Extensively Drug-Resistant Shigella Cases in LAC. See LAC DPH Health Advisory.
  • August 9, 2024: Rise in Extensively Drug-Resistant Shigella Strains, January to May 2024. See CDPH Health Advisory.
  • February 24, 2023: Increase in Extensively Drug-Resistant Shigellosis in the United States. See CDC Health Advisory.
Prevention
  • Wash your hands with soap and water especially after using the bathroom, changing a diaper, and before preparing or eating food.
  • Avoid swallowing water while swimming.
  • When traveling internationally, follow safe food and water habits.
  • If you or your partner has been diagnosed with shigellosis, do not have sex for at least two weeks after the diarrhea ends.
  • People who work in healthcare, food service, or childcare, might be kept from work until they recover.
Information for Clinicians
This Shigella antibiogram for Los Angeles County is based on data from the National Antimicrobial Resistance Monitoring System (NARMS), which tracks emerging resistance in enteric bacteria across the U.S. using isolates from human cases. The antibiogram supports evidence-based treatment by highlighting local antibiotic susceptibility patterns, which are critical for managing shigellosis. The data represent the percentage of Shigella isolates susceptible to each antibiotic per year.

* Preliminary data include records from years after 2023, when isolate collection and/or testing is still in progress.
† Rank of antimicrobial agents is based on World Health Organization's categorization of critical importance in human medicine. Rank I, Critically Important; Rank II, Highly Important
‡ CLSI: Clinical and Laboratory Standards Institute

Symptoms

Symptoms of shigellosis are self-limited and last 5-7 days. They include:

  • Watery, bloody, or prolonged diarrhea
  • Tenesmus
  • Abdominal pain
  • Fever
  • Malaise
Diagnosis
  • Consider shigellosis in the differential diagnosis of acute diarrhea, especially for patients at higher risk for Shigella infection, including:
    • Young children
    • Men who have sex with men
    • People experiencing homelessness
    • International travelers
    • Immunocompromised persons
    • People with HIV
Testing
  • Stool culture with susceptibility testing (AST) is recommended for patients who require antibiotic treatment.
  • If a culture-independent diagnostic test (CIDT, e.g. Gastrointestinal Panel) is performed, request on sample submission that the clinical laboratory perform reflex culture if positive for Shigella.
  • AST should cover a complete antibiotic profile for Shigella (azithromycin, ciprofloxacin, ceftriaxone, trimethoprim-sulfamethoxazole, and ampicillin).
Treatment

Shigella is self-limiting and most patients will recover without antibiotic treatment. Given the rise in multi-drug resistance, judicious antibiotic use is recommended.

  • Avoid prescribing fluoroquinolones for ciprofloxacin minimum inhibitory concentration (MICs) in the 0.12–1.0 μg/mL range.
  • If antimicrobial treatment is warranted due to severe or prolonged illness, hospitalization, or underlying risk factors such as immunocompromising conditions (e.g., HIV/AIDS or immunosuppressive therapy), clinicians should initiate therapy based on the best available data. Once antimicrobial susceptibility results are available, treatment should be adjusted accordingly.
  • See antibiogram for Los Angeles County.
Reporting
  • Los Angeles County suspect cases are reportable within 1 working day from identification by electronic transmission (including FAX at 888-397-3778), telephone (888-397-3993) or mail by completing a confidential morbidity report.
  • Report all cases and AST results to the Los Angeles County Department of Public Health.
  • An isolate or specimen is required to be sent to the public health laboratory per CA CCR Title 17 Reportable Disease Guidance.