Shigellosis

Shigellosis, historically known as dysentery, is an intestinal infection caused by bacteria of the genus Shigella, which are gram-negative bacilli genetically related to Escherichia coli. The etiologic agents comprise four distinct species or serogroups: Shigella sonnei, Shigella flexneri, Shigella dysenteriae, and Shigella boydii. These organisms possess the capacity to invade the colonic epithelium and produce enterotoxins that contribute to the characteristic inflammatory response and clinical manifestations of the disease.

The clinical presentation of shigellosis ranges from mild, self-limited diarrhea to severe dysentery with systemic complications. Onset typically occurs within 12 to 96 hours following exposure, with symptoms including watery or bloody diarrhea, fever, abdominal cramps, and tenesmus. The illness usually persists for five to seven days, though complete normalization of bowel habits may require several months. Severe complications may include reactive arthritis, hemolytic uremic syndrome, sepsis, and seizures, particularly in young children and immunocompromised individuals. Dehydration resulting from fluid loss represents a primary clinical concern requiring attention.

Shigellosis exhibits a worldwide distribution, though the relative prevalence of specific Shigella species varies geographically. Shigella sonnei predominates in industrialized nations including the United States, while Sh. dysenteriae and Sh. boydii are more commonly encountered in developing regions. The infection primarily affects populations with limited access to clean water and adequate sanitation infrastructure, though outbreaks also occur in congregate settings such as childcare facilities and institutional environments. Humans serve as the primary reservoir, with asymptomatic carriers capable of transmitting the organism despite the rarity of long-term carriage.

Shigella is transmitted via the fecal-oral route through direct or indirect contact with infectious fecal material. Transmission occurs through consumption of contaminated food or water, person-to-person contact including sexual transmission, and environmental vectors such as flies. The bacterium is notably resistant to gastric acid, requiring an infectious dose of only 10 to 200 organisms to establish infection—several orders of magnitude lower than many other enteric pathogens. This low infectious dose facilitates efficient spread in settings with poor hygiene practices, including diaper changing and inadequate handwashing.

Children under five years of age experience the highest incidence of shigellosis and are at greatest risk for severe outcomes including dehydration and death. Immunocompromised individuals, including those with HIV infection, face elevated risks of complicated disease and prolonged carriage. Travelers to endemic areas, men who have sex with men, and individuals in congregate living settings such as childcare centers and correctional facilities represent populations at increased exposure risk. The elderly and those with underlying malnutrition also demonstrate heightened susceptibility to severe disease.

Prevention of shigellosis centers on interruption of fecal-oral transmission through improved water, sanitation, and hygiene practices. Proper handwashing with soap and clean water represents the most effective individual-level preventive measure, particularly after defecation, diaper changes, and before food preparation. Currently, no licensed vaccine exists for shigellosis, though vaccine development remains an active area of research. In outbreak settings, environmental decontamination, isolation of symptomatic individuals, and exclusion of ill food handlers from work until clearance criteria are met serve as important supplementary control measures.

Surveillance for shigellosis relies primarily on laboratory confirmation through stool culture, which remains the diagnostic standard despite the advent of molecular methods. The organism is characterized biochemically by non-motility, absence of lactose fermentation with the exception of Sh. sonnei, and negative urea hydrolysis. Given the low infectious dose and potential for rapid spread, timely case identification and reporting are essential for outbreak detection and control. Antimicrobial susceptibility testing is increasingly important given rising resistance rates, which complicate treatment decisions in severe cases.

1. 1 Wikidata. shigellosis.
2. 2 Wikipedia. Shigellosis - Wikipedia.

ICD-10

ICD-11

Total cases

182K

Peak month

2008-11

Coverage

2 reporting countries · 2000-01-01 → 2026-05-09