Cholera

Background

• Endemic to Asia, Africa, and Central and South America
• Occasionally seen on the Gulf Coast of US, due to inadequately cooked seafood.

Pathophysiology

• Usually Vibrio cholera, which produces an enterotoxin which causes a secretory diarrhea

Natural History

• Transmission via ingestion of contaminated food or water, usually undercooked seafood
• Incubation period between hours to 5 days, depending on size of inoculum (usually 1-2 days)
• Most people are asymptomatic, and simply have bacteria in their feces for 7-14 days
• Diarrhea is most severe in days 1-2, usually resolves in 7 days

Vibrio species

• Vibrio cholerae
• Vibrio vulnificus
• Vibrio parahemolyticus

Clinical Features

• Classic “rice water” diarrhea with fishy odor; usually painless
• Fluid losses can be significant, up to 1L/hr, leading to severe fluid and electrolyte depletion. However, most cases are mild.
• Occasionally seen: sudden watery vomiting, borborygmi, abdominal cramping.

Later manifestations:

• Fluid loss may lead to → sunken eyes, dry mouth, cold clammy skin, decreased skin turgor, or wrinkled hands and feet (also known as “washer woman’s hands”)
• Acidosis from loss of bicarbonate
• Muscle cramps from loss of K, Ca

Differential Diagnosis

Acute diarrhea

Infectious

• Viral (e.g. rotavirus)
• Bacterial
  • Campylobacter
  • Shigella
  • Salmonella (non-typhi)
  • Escherichia coli
    • E. coli 0157:H7
  • Yersinia enterocolitica
  • Vibrio cholerae
  • Clostridium difficile
• Parasitic
  • Giardia lamblia
  • Cryptosporidium
  • Entamoeba histolytica
  • Cyclospora
  • Microsporidium
• Toxin
  • Staphylococcus aureus
  • Bacillus cereus

Noninfectious

• GI Bleed
• Appendicitis
• Mesenteric Ischemia
• Diverticulitis
• Adrenal Crisis
• Thyroid Storm
• Toxicologic exposures
• Antibiotic or drug-associated

Watery Diarrhea

• Enterotoxigenic E. coli (most common cause of watery diarrhea)
• Norovirus (often has prominent vomiting)
• Campylobacter
• Non-typhoidal Salmonella
• Enteroaggregative E. coli (EAEC)
• Enterotoxigenic Bacteroides fragilis

Traveler's Diarrhea

• Giardia lamblia
• Cryptosporidiosis
• Entamoeba histolytica
• Cyclospora

Diagnosis

Work-up

• Fecal smears will NOT show leukocytes or erythrocytes.
• Diagnosis can be confirmed by stool cultures on TCBS medium (must inform lab cholera is suspected so appropriate medium is used)

Evaluation

• Diagnosis largely based on clinical presentation + epidemiological risk factors

Management

• Aggressive volume repletion. Usually can be given orally if mild/moderate volume depletion; give rehydration solution to replete electrolyte loss.
• Oral rehydration solution includes in 1L of water: 2.6g NaCl, 2.9g Trisodium citrate, 1.5 g KCl, and 13.5 g glucose.

• If severe dehydration, bolus with 100 ml/kg over 3 hrs. LR is solution of choice. May require more than 350 ml/kg in first 24 hours.

• Antibiotic treatment decreases severity and duration of disease. Antibiotic resistance patterns are changing constantly. Most recommended currently is azithromycin 20mg/kg single dose.

• Alternatives: ciprofloxacin 1g single dose; doxycycline 300mg single dose; TMP-SMX double strength BID for 3 days; erythromycin 500 QID for 3 days.

• Give children Zinc and Vitamin A.

Disposition

• Admit if hypotensive or hemodynamically unstable, severe electrolyte abnormalities

See Also

• Diarrhea
• Travel Medicine