Cholera

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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

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 of 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

Workup

  • Diagnosis largely clinical presentation + epidemiological risk factors
  • Fecal smears will NOT show leukocytes or erythrocytes.
  • Diagnosis can be confirmed by stool cultures on TCBS medium (tell the lab cholera is suspected, so appropriate medium is used).

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.

Sources

  • Marx et al. “Cholera and Gastroenteritis caused by Noncholera Vibrio Species”. Rosen’s Emergency Medicine 8th edition vol 1 pg 1245-1246.
  • Sack DA, et al. Cholera. Lancet 2004; 363:223.
  • LaRocque R and Harris J. “Overview of Cholera”, UpToDate.com
  • LaRocque R and Pietroni M. “Approach to the Adult with Acute Diarrhea in Developing Countries”. UpToDate.com
  • World Health Organization. Cholera Fact Sheet. Feb 2014
  • http://www.ncbi.nlm.nih.gov/pubmed/24481887
  • http://www.ncbi.nlm.nih.gov/pubmed/20372681

Authors

Kavita Joshi, MD and Alex Koyfman MD
Department of Emergency Medicine, UT Southwestern Medical Center / Parkland Memorial Hospital, Dallas, Texas, USA