Shigellosis natural history, complications and prognosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Infections are associated mucosal ulceration, rectal bleeding, drastic dehydration; fatality may be as high as 10-15% with some strains. Reiter's disease, reactive arthritis, and hemolytic uremic syndrome are possible sequelae that have been reported in the aftermath of shigellosis.

Natural History

Ingestion of Shigella

• Not all individuals develop clinical manifestations of shigellosis. Individuals may remain asymptomatic but transmit the organism to other individuals.

Development of Clinical Manifestations

• Clinical manifestations of shigellosis typically appear approximately 12 hours to 3 days following ingestion of Shigella".
• Patients generally first develop colicky diffuse abdominal pains associated with nausea and fever.
• Diarrhea and tenesmus (rectal spasms) typically follow. Diarrhea is often reported to be small in volume and may range from mild to severe. The majority of patients report mucus in stools, and up to half of infected patients report bloody stools. Children younger than 2 years of age may develop high-grade fevers and febrile seizures.

Resolution of Clinical Manifestations

• If left untreated, clinical manifestations of shigellosis typically self-resolve within 5 to 7 days of development of clinical manifestations.
• In immunocompromised individuals and young children, shigellosis may be more severe and prolonged, necessitating hospitalization to reduce the risk of shigella-associated complications.

Complications

Complications are generally rare among immunocompetent individuals. The risk of complications increases among HIV-positive individuals and among young children. Approximately 1 of 10 children develop complications of shigellosis.

Reiter's syndrome is a late complication of S. flexneri infection, especially in persons with the genetic marker HLA-B27. Hemolytic-uremic syndrome can occur after S. dysenteriae type 1 infection. Convulsions may occur in children; the mechanism may be related to a rapid rate of temperature elevation or metabolic alterations

Intestinal Complications

• Rectal prolapse
• Proctitis
• Toxic Megacolon
• Colonic Perforation

Systemic Complications

• Post-infectious arthritis (Reiter's syndrome)
  • Approximately 2% of individuals infected with S. flexneri develop Reiter's syndrome (triad of arthritis, uveitis, and urethritis).
  • Post-infectious arthritis may persist for several weeks to months and may become chronic.
  • Individuals with HLA-B27 subtype are predisposed to development of Reiter's syndrome following shigellosis.
• Bacteremia
  • Bacteremia is common among immunocompromised individuals, such as HIV-positive individuals and individuals with cancer and malnutrition.
• SIADH and SIADH-associated hyponatremia
• Seizure
  • Febrile seizres are common among children less than 2 years of age.
• Encephalopathy (especially among children)
• Reactive arthritis
• Hemolytic uremic syndrome (HUS)
  • HUS is mediated by Shiga toxin that is typically present in S. dysenteriae.
• Microangiopathic hemolytic anemia (MAHA)
• Thrombocytopenia
• Acute Renal Failure

Prognosis

Often the infection is mild and goes away on its own. Most patients, except malnourished children and those with weakened immune systems, have an excellent outlook.

References

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