Epidemiology

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Etiology

Watery diarrhea

Viral

	Norovirus (Norwalk) virus	Rotaviruses	Adenovirus	Astrovirus
Genome/structure	Positive ss RNA, non-enveloped, Star of David	ds RNA (11 segments), non-enveloped, Wheel-like	ds DNA, non-enveloped, type 40/41, fibers (penton)	Positive ss RNA, non-enveloped
High risk	Group settings, e.g., cruise ships	Infants	Infants, older children, adults	Infants, elderly, immunocompromised
Seasonality	Occurs year round	November-April peak	Late fall and winter peak	Winter peak
Vaccine	No	Yes Prevalence in developed countries has decreased dramatically due to vaccination.	No	No

Bloody diarrhea

• Campylobacter jejuni
  • Poultry, unpasteurized milk (natural gut flora in birds)
  • Contact with infected persons or infected animals (e.g., pigs, dogs, cats)

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Pathophysiology

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Clinical features

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Diagnostics

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Treatment

Antidiarrheal agents

• Bismuth subsalicylate
  • Converts to bismuth and salicylic acid in the GI tract
  • Has antisecretory, antimicrobial, and antiinflammatory effects
  • Can be used in bacterial diarrhea
• Loperamide
  • Opioid receptor agonist that increases intestinal transit time
    • Loperamide acts on intestinal μ-receptors and inhibits intestinal peristalsis and intestinal fluid secretion, and increases sphincter tone.
  • Best initial treatment for chemotherapy-induced diarrhea
  • Cautions
    • Should not be used for > 48 hours without reevaluation of the patient

Warning

Loperamide should be avoided in patients with suspected invasive diarrhea with inflammatory features, as it reduces intestinal motility, which consequently increases the risk of bacterial colonization and invasion.

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