Shigellosis natural history, complications and prognosis

Clinical manifestations of shigellosis typically develop 12 hours to 3 days following ingestion of Shigella. Patients often first develop colicky diffuse abdominal pain and fever, followed by diarrhea and tenesmus. If left untreated, shigellosis self-resolves within 5 to 7 days of onset of clinical manifestations in the majority of patients. High risk patient populations (young children, elderly, and immunocompromised patients) are at increased risk of developing complications, which may be intestinal or extra-intestinal. Classical complications include post-infectious arthritis and hemolytic uremic syndrome (HUS). Prognosis is generally excellent for immunocompetent individuals. Factors that are associated with poorer prognosis include prolonged duration of disease, development of complications, and infection of high risk patients.

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

• Clinical manifestations of shigellosis typically appear approximately 12 hours to 3 days following ingestion of Shigella.
• Patients typically 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 diarrhea is usually watery at first, but patients may also develop dysentery.
• Children younger than 2 years of age may develop high-grade fevers and febrile seizures.

• 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.

• Rectal prolapse
• Proctitis
• Toxic megacolon
• Intestinal obstruction
• Colonic perforation

• 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.
• Concomitant infections
  • Patients with dysentery lose proteins, including immune factors, in stools and are predisposed to concomitant infections that are not related to 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
  • Among children less than 2 years of age.
• Encephalopathy
  • Among children less than 2 years of age.
• Reactive arthritis
• Hemolytic uremic syndrome (HUS)
  • HUS is mediated by Shiga toxin that is typically present in S. dysenteriae.
  • HUS is characterized by the triad microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury.^[1]
• Bronchopneumonia

• Disseminated intravascular coaguloapathy (DIC)

• Cholestatic hepatitis
• Myocarditis
• Coma
• Death

• Generally, prognosis of shigellosis is excellent, and the majority of patients recover without sequelae.
• Factors associated with poorer prognosis include:
  • Prolonged duration of disease (> 7 days)
  • Development of complications
  • Patient risk factors (young children, elderly patients, or immunocompromised patients).

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