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Shigella

What is it?

Shigella species are gram-negative bacteria, belonging to the Enterobacteriaceae family, and are the causative agents of shigellosis, a highly infectious gastrointestinal illness. (1-3) Shigella can be divided into four species: Shigella boydii, Shigella dysenteriae, Shigella flexneri, and Shigella sonnei. (4) Globally, Shigella flexneri and Shigella sonnei account for the highest proportion of infections and are considered endemic in many regions. (4)

Controlling the burden of Shigella presents several challenges, including the low infectious dose needed for transmission and infection, and the possibility of re-infection from different species being high. (3) The need for antibiotic treatment has resulted in the emergence of multidrug-resistant Shigella genotypes, which now represent a significant and growing public health concern. (3, 4)

Signs and Symptoms

Shigella invades the gut epithelium and causes signs and symptoms of diarrhoea, fever, nausea, vomiting, stomach cramps, and blood in the faeces. (4, 5) Symptoms typically develop within 1 to 3 days following exposure and generally last 4 to 7 days. (5) Shigellosis is usually self-limiting, and most people recover within a week without treatment. (2)

In rare cases, people without symptoms can carry and spread the Shigella bacteria for months. (2)

How is it transmitted?

Shigella is primarily transmitted via the faecal-oral route. This includes through ingestion of contaminated food or water, direct contact with infected faeces, handling soiled nappies and linens of an infectious person, or through close or intimate contact with an infectious person. (2, 5) People are most infectious while symptomatic, particularly during episodes of diarrhoea and for up to two days after diarrhoea has stopped. (2)

At risk groups?

Shigella is the leading bacterial cause of diarrhoeal disease globally, responsible for an estimated 270 million cases and over 200,000 deaths annually. (3) The burden is highest in low- and middle-income countries with a high incidence in children under the age of 5. (3)

People at risk of Shigella infection include children, the elderly, immunocompromised individuals, people who travel to countries where Shigella is common, and men who have sex with men. (5)

Prevention?

There is currently no vaccine available for Shigella; however, there are several vaccines in development and undergoing clinical trials. (3, 6) The rise of multidrug-resistant Shigella and the impact on morbidity and mortality have meant that the development of a Shigella vaccine is an important World Health Organization goal for public health. (6)

Preventative strategies for Shigella infection include infection prevention and control measures, adherence to standard and transmission-based precautions, hand hygiene and safe food practices that include washing fruit and vegetables that are eaten raw. (1, 5)

Safe travel advice is recommended for people who travel to countries where Shigella is common. This includes avoiding the consumption of uncooked or raw foods, unless they are able to be peeled before eating, avoiding untreated water or ice, only drinking bottled or boiled water and ensuring hot food has been thoroughly cooked. (5)

People who have Shigella infection should not prepare food, attend work or care for people while they are unwell, to prevent transmission of infection. (2, 5)

References

  1. National Health and Medical Research Council (NHMRC). Australian Guidelines for the Prevention and Control of Infection in Healthcare. Canberra: National health and Medical Research Council; 2019.
  2. Australian Centre for Disease Control. Shigellosis (Shigella infection) Canberra, : Australian Centre for Disease Control. ; 2026 [updated 17 February 2026. Available from: https://www.cdc.gov.au/diseases/shigellosis-shigella-infection.
  3. Raso MM, Arato V, Gasperini G, Micoli F. Toward a Shigella Vaccine: Opportunities and Challenges to Fight an Antimicrobial-Resistant Pathogen. International Journal of Molecular Sciences [Internet]. 2023; 24(5):[4649 p.].
  4. Miles SL, Holt KE, Mostowy S. Recent advances in modelling <em>Shigella</em> infection. Trends in Microbiology. 2024;32(9):917-24.
  5. NSW Health. Shigella (shigellosis) fact sheet Sydney: NSW Health; 2025 [updated 18 December 2025. Available from: https://www.health.nsw.gov.au/Infectious/factsheets/Pages/shigellosis.aspx.
  6. World Health Organization. Shigella: World Health Organization; 2022 [Available from: https://www.who.int/teams/immunization-vaccines-and-biologicals/diseases/shigella.