References:

Global Infectious Diseases and Epidemiology Online Network: Infectious Diseases of the Philippines, 2013 eBook Edition, ISBN 978-1-61755-582-4, by Stephen Berger. Accessed here.


Agent	BACTERIUM. Shigella sonnei, Shigella flexneri, Shigella boydii or Shigella dysenteriae A facultative gram-negative bacillus
Reservoir	Human Non-human primate
Vector	None
Vehicle	Fecal-oral Water Dairy products Fomite Fly Vegetables
Incubation Period	48 to 72 hours (As early or late as 7 hours to 1 week)
Diagnostic Tests	Stool culture
Typical Adult Therapy	Stool precautions. Choice of antimicrobial agent based on regional susceptibility patterns. Continue treatment for five days
Typical Pediatric Therapy	As for adult
Clinical Hints	Watery or bloody diarrhea, tenesmus, abdominal pain and headache; colonic hyperemia and abundant fecal leucocytes are present; usually resolves in 3 days (may persist for up to 14); case fatality rate = 1%.
Synonyms	Bacillaire dysenterie, Bacillary dysentery, Dissenteria batterica, Dysenteria bacillaris, Leptospirenerkrankung, Ruhr, Shigella, Shigellose, Shigelose, Ubertragbare Ruhr

Acute Infection

Approximately 50% of infections are limited to transient fever or self-limited diarrhea.

50% of patients progress to bloody diarrhea and dysentery.
Fever may rise rapidly to 40°C, and febrile seizures are common in children.
Seizures rarely recur or result in neurological sequelae.
Dysentery is characterized by passage of 10 to 30 small-volume stools consisting of blood, mucus, and pus.
Abdominal cramps and tenesmus are noted, and straining may lead to rectal prolapse, notably in young children.
On endoscopy, the colonic mucosa is hemorrhagic, with mucous discharge and focal ulcerations. Most lesions are in the distal colon.

Complications

Patients with mild disease generally recover without specific therapy in two to seven days.

Severe shigellosis can progress to toxic dilatation or perforation of the colon, which may be fatal.
Mild dehydration is common, and protein-losing enteropathy can occur with severe disease.
Complications are most commonly described in developing countries and are related both to the relative prevalence of S. dysenteriae type 1 and S. flexneri, and the poor nutritional state of the local populations.
Shigella bacteremia is not uncommon, and is associated with increased mortality, particularly among infants below one year of age and persons with protein-energy malnutrition.
Hemolytic-uremic syndrome (HUS) may complicate shigellosis due to S. dysenteriae type 1, and usually develops toward the end of the first week of shigellosis. The case-fatality rate in these cases is 36%.
Profound hyponatremia and hypoglycemia may occur.
Other complications include encephalopathy, seizures, altered consciousness, and bizarre posturing, pneumonia, meningitis, vaginitis, keratoconjunctivitis, pneumonia and “rose spots.”
Reiter’s syndrome is seen in patients having histocompatibility antigen HLA-B27.
Reactive arthritis follows 7% to 10% of Shigella infections.