Excerpt from Shigellosis

Synonyms, Key Words, and Related Terms: bacillary dysentery, Shigella organisms, Shigella boydii, Shigella dysenteriae, Shigella sonnei, Shigella flexneri

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Background

Shigella organisms cause bacillary dysentery, a disease that has been described since early recorded history.

Pathophysiology

Shigella species are aerobic, nonmotile, glucose-fermenting, gram-negative rods that are highly contagious, causing diarrhea after ingestion of as few as 180 organisms. Shigella species cause damage by 2 mechanisms, invasion of the colonic epithelium, which is dependent on a plasmid-mediated virulence factor, and production of enterotoxin, which is not essential for colitis but enhances virulence. The organism is spread by fecal-oral contact; via infected food or water; during travel; or in long-term care facilities, day care centers, or nursing homes.

Frequency

United States

Approximately 15,000 cases of shigellosis are reported annually in the United States.

International

Shigellosis occurs worldwide, and it tends to occur whenever war, natural calamities (eg, earthquakes, floods), or unhygienic living conditions result in overcrowding and poor sanitation. Shigella boydii and Shigella dysenteriae occur more commonly internationally. In impoverished countries, Shigella flexneri and S dysenteriae cause more than 600,000 deaths per year.

Mortality/Morbidity

Infection with Shigella species may be associated with extragastrointestinal complications.

Bacteremia occurs primarily in malnourished children and carries a mortality rate of 20% as a result of renal failure, hemolysis, thrombocytopenia, gastrointestinal hemorrhage, and shock.
Hemolytic uremic syndrome may complicate infections with Shigella species and Escherichia coli, and it carries a mortality rate greater than 50%. Hemolytic uremic syndrome is characterized by acute hemolysis, renal failure, uremia, and disseminated intravascular coagulation.

Race

No racial differences exist.

Sex

No sexual predilection exists in Shigella infections. Reiter syndrome, which is a triad of arthritis, urethritis, and conjunctivitis, occurs most commonly in men aged 20-40 years, and it occurs 2-4 weeks after infection with the Shigella species. Reiter syndrome is associated with the human leukocyte antigen (HLA)–B27 phenotype. The arthritis is asymmetrical and can be chronic and relapsing.

Age

Shigellosis is most common in children aged 6 months to 5 years.

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