Shigellosis causes fever, abdominal cramping, nausea, and bloody diarrhea lasting for 5-7 days. Outbreaks are seen in crowded institutional settings where residents have poor personal hygiene and also among men who have sex with men. Flies may transmit infection from latrines.
CASES/YEAR
448,240 (US); 125,000,000 (Global)
OTHER NAMES
Bacillary dysentery; Shigella dysenteriae, S. flexnerii, S. sonnei, or S. boydii infection;
INCUBATION
Usually 1-3 days; 12 hours to one week for S. dysenteriae type 1; [CCDM]
INITIAL SYMPTOMS
Acute gastroenteritis with fever, abdominal cramping, nausea, and bloody diarrhea lasting for 5-7 days; [CDC Travel]
PRECAUTIONS
Standard; "Use Contact Precautions for diapered or incontinent children for duration of illness and to control institutional outbreaks." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
FINDINGS:
In typical cases, patients have fever, abdominal cramping, and voluminous diarrhea initially, followed by frequent stools of smaller volume. Then within another day or two, patients have bloody, mucoid stools and rectal urgency. In retrospective analyses, 1/3 of patients with shigellosis have fever, 2/5 have grossly bloody stools. An increased percentage of immature neutrophils in the CBC differential (shift to the left) is typical in bacillary dysentery. Both leukopenia and leukocytosis are occasionally seen. Other complications of untreated infections are septicemia, pneumonia, and immune-complex glomerulonephritis. A reactive arthritis 2-5 weeks after the acute illness may occur in up to 10% of patients. [PPID, p. 2740-1, 1358] Febrile convulsions may be seen in children. Some strains cause a mild, self-limited infection lasting up to a week. Shigella dysenteriae type 1 (Shiga bacillus) causes epidemics and often severe disease with complications including toxic megacolon, intestinal perforation, and hemolytic-uremic syndrome. Some strains of Shigella flexnerii can cause reactive arthritis. [CCDM, p. 556-7] Shigella bacteria can cause conjunctivitis and keratitis. [Guerrant, p. 1004] Functional bowel obstruction may accompany toxic megacolon. Bacteremia is extremely uncommon in the US. Of isolates reported to the CDC, >99% are from stool specimens. [Guerrant, p. 141] "Infection may manifest as delirium, seizures, and coma but with little or no diarrhea." [Merck Manual, p. 1597] Children <5 years old may develop a neurological syndrome (lethargy, seizures, delirium, and coma) with a poor prognosis. [Harrison ID, p. 546] This syndrome is often associated with hypoglycemia and hyponatremia. [Cecil, p. 1946]
EPIDEMIOLOGY:
Outbreaks are seen in crowded institutional settings where residents have poor personal hygiene and also among men who have sex with men. Daycare attendees have increased risk for infection. Flies may transmit infection from latrines. [CCDM, p. 558] E. coli O157:H7, salmonella, and shigella are possible agents of bioterrorism. [www.bt.cdc.gov] Foodborne outbreaks occur through infected food handlers and contaminated food commonly eaten raw. [CDC Travel, p. 341] "Shigella dysenteriae type 1 (not commonly present in the US, except in travelers returning from endemic areas) produces Shiga toxin, which causes marked watery diarrhea and sometimes hemolytic-uremic syndrome." [Merck Manual, p. 1596] Of the estimated 165 million cases per year in the world, 69% occur in children <5 years of age. [Harrison ID, p. 544]
DIAGNOSTIC
Culture of stool specimen or rectal swab; Process rapidly because organisms cannot live long outside the body; Rapid diagnostic tests are increasingly available, but cultures should be done. [CDC Travel]
SCOPE
Global; Shigella sp. in stools of about 5-18% of patients with travelers' diarrhea; [CDC Travel, p. 341] Outbreaks occur in the setting of overcrowding and poor personal hygiene; [CCDM, p. 558]
SIGNS & SYMPTOMS
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>fever
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>myalgia
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G abdominal pain
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G blood in stool
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G diarrhea
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G fecal leukocytes
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G nausea, vomiting
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H anemia
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H hemolysis
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H leukocytosis
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H leukopenia
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H thrombocytopenia
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N confusion, delirium
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N lethargy
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N seizure
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O conjunctivitis, acute
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*acute renal failure
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*arthritis
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*bowel obstruction
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*erythema nodosum
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*glomerulonephritis
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*myocarditis
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*pneumonia
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*sepsis
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*stupor, coma
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*uveitis
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*weight loss
ENTRY
Ingestion, Swimming, Sexual Contact
SOURCE
Person-to-Person, Human Fecal-Oral, Eating Contaminated Food, Eating Unpasteurized Milk or Cheese, Eating Contaminated Produce, Waterborne (Ingesting, Inhaling, or Swimming)
RISK FACTORS
- Care for patients (fecal-oral pathogens)
- Consume unpasteurized milk/cheese
- Ingest infectious agents in food/water
- Swim in contaminated water (ingestion or inhalation)
- Travel to endemic area
- Victim--water/food release
TREATMENT
Children, the elderly, and patients with debilitation or severe disease should be treated with antibiotics; [Merck Manual, p. 1596]
REFERENCES FOR CASES/YEAR
1. (US) MMWR 2011: 13,352; 6.24/100,00 in 2007; [Gorbach, p. 10] Calculate for population of 300 million = 18720; Estimated 448,240 cases in 1997; [Mead1999: PMID 10511517]
2. (Global) WHO estimated 165 million per year from 1966-1997 with 69% of cases in children <5 years old and 500,000 to 1.1 million estimated deaths per year; [Harrison ID, p. 544] Causes an estimated 125 million cases/year and 14,000 deaths/year; [CCDM, p. 557]