Description

• An acute infectious disease caused by the gram-negative bacterium Vibrio cholerae
• Characterized by severe diarrhea with extreme fluid and electrolyte depletion, vomiting, muscle cramps, prostration, and potential death without fluid and electrolyte replacement (1)
• Endemic areas: India, Southeast Asia, Africa, Middle East, Southern Europe, Oceania, South and Central America (1)
• System(s) affected: gastrointestinal
• Synonym(s): Asiatic cholera; epidemic cholera; rice-water diarrhea; cholera gravis

Pregnancy Considerations
Cholera in 3rd trimester of pregnancy is associated with greater dehydration and may lead to stillbirth. Significant dehydration is the greatest risk for poor fetal outcome.

Pediatric Considerations

• Vaccine is not recommended for children <6 months.
• Breastfeeding is protective.

Epidemiology

• Predominant age: all ages
• Predominant sex: male = female
• 75% of patients infected with V. cholerae do not develop symptoms. Patients continue to shed the organism in their feces for 1 to 2 weeks after infection.
• 80% of clinical cases are mild to moderate; 20% are severe with high fatality rates if untreated.
• Most U.S. cases acquired through international travel
• El Tor (O1) is the predominant biotype and is responsible for the most recent epidemic (1).
• New serotype in Bangladesh, India (0139). Important because of lack of efficacy of standard vaccine; several new variants reported in Asia and Africa
  • Usual course: acute, chronic, and relapsing
  • In the early stages, severely affected patients can lose 1 L/hr of body fluids (1).

Incidence
Seven cholera epidemics have occurred in the past 200 years (1).

Prevalence
An estimated 100,000 deaths and 3 million cases per year (2)

Etiology and Pathophysiology

• After ingesting an infectious dose (>10⁸ organisms) through contaminated food/water sources, the organism reaches the small intestine where V. cholerae (O-group 1) produces an enterotoxin (CTX) that promotes fluid secretion into the intestinal lumen.
• Toxicity is mediated by A1 enterotoxin subunit, which increases cyclic adenosine monophosphate (cAMP) production. This results in a reduction of sodium and chloride absorption by intestinal microvilli and an increase in fluid excretion (massive watery diarrhea).
• The incubation period is 12 hours to 5 days, with a median of 1.5 days (1).

Risk Factors

• Traveling or living in epidemic/endemic areas
• Exposure to contaminated food or water
• Person-to-person transmission (rare)
• In endemic areas, children <5 years of low socioeconomic status who do not breastfeed are at highest risk.
• Cases are more severe in patients with blood group O compared with AB (patients with blood types A, B, and AB have blood group antibodies in the mucosal layer which delays cholera toxin penetration of the small bowel [1]).
• Reduced gastric acid secretion: medications, gastrectomy

General Prevention

• Water purification
• Appropriate public sanitation
• Proper food selection and preparation (e.g., no unpeeled raw fruits or vegetables, no raw or undercooked seafood)
• Enteric precautions
• Chemoprophylaxis for exposed contacts is not routinely recommended (2,3)[C].
• Natural infection confers long-lasting immunity.
• Nutrition:
  • WHO recommends zinc supplementation (20 mg/day) in children 12 months to 5 years who are nutritionally deficient to reduce the incidence and prevalence of acute infectious diarrhea (1)[A].
• Prophylactic vaccine
  • Not recommended for routine traveler’s diarrhea or dysentery 2[A]
  • The FDA-approved vaccine is for adults 18 to 64 years traveling to an area of active cholera transmission. It reduces severe diarrhea by 90% at 10 days and 80% at 90 days following vaccination. Safety in pregnant and breastfeeding women is unknown.
  • Two other vaccines are available outside the United States. Both provide longer immunity in adults compared, often up to 2 years from a single dose and up to 3 to 4 years with annual boosters (1)[A]. WHO recommends use of these in endemic areas (1)[C].
  • Concomitant administration with yellow fever vaccine may decrease response to yellow fever.

Commonly Associated Conditions

Increased risk of disease with gastric achlorhydria