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For further information, see CMDT Part 15-06: Diarrhea
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Essentials of Diagnosis
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Acute noninflammatory diarrhea
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Watery, nonbloody
Usually mild, self-limited
Caused by a virus or noninvasive, toxin-producing bacterium
Diagnostic evaluation is limited to patients with diarrhea that is severe or persists beyond 7 days
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Acute inflammatory diarrhea
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Blood or pus, fever
Usually caused by an invasive or toxin-producing bacterium
Diagnostic evaluation requires routine stool bacterial testing (including E coli O157:H5 and O157:H7) in all patients and testing as clinically indicated in others for Clostridioides difficile and parasites
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General Considerations
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Most commonly caused by infectious agents, bacterial toxins (Table 30–3), or drugs
Similar recent illnesses in family members suggests infectious diarrhea
Community outbreaks (including norovirus and SARS-CoV-2 in nursing homes, schools, cruise ships) suggest a viral etiology or a common food source
Among patients with COVID-19 infection, watery diarrhea (usually mild) occurs in one-third and it may be the presenting symptom in 3–16%
Ingestion of improperly stored or prepared food may result in diarrhea from preformed toxin in the food or from invasive bacteria produced within the gastrointestinal tract after its ingestion
Exposure to unpurified water suggests Giardia or Cryptosporidium
Large Cyclospora outbreaks have been traced to contaminated produce
Recent travel abroad suggests "traveler's diarrhea"
Antibiotic administration suggests C difficile colitis
HIV infection or sexually transmitted diseases suggest AIDS-associated diarrhea
Proctitis and rectal discharge suggest gonorrhea, syphilis, lymphogranuloma venereum, and herpes simplex
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