Bacillary dysentery; Shigella dysenteriae, S. flexnerii, S. sonnei, or S. boydii infection;
Acute gastroenteritis with fever, abdominal cramping, nausea, and bloody diarrhea lasting for 4-7 days; [CDC Travel]
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. 2572-3, 1265] 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] Jaundice is a finding in some patients with hemolytic-uremic syndrome. [Cohen, p. 1081] 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. 1263] Children <5 years old may develop a neurological syndrome (lethargy, seizures, delirium, and coma) with a poor prognosis. [Harrison ID, p. 576] This syndrome is often associated with hypoglycemia and hyponatremia. [Cecil, p. 1889]
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. 319] "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. 1263] Of the estimated 165 million cases per year in the world, 69% occur in children <5 years of age. [Harrison ID, p. 574]
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