- Various modern outbreaks
- Yemen as of 2016-2017 has the largest Cholera outbreak in history
- Bangladash (1993 post-monsoon potable water contamination)
- Latin America and South America (1991 improper sewage processing)
- Indonesia had onset in the 1960s of an ongoing Cholera epidemic
- Cholera was limited to Asia until 1817, when it spread to India and then globally
- London Physician John Snow (1813-1858)
- Famous role in public health history
- Linked Cholera outbreak to Broad Street Pump in 1854
- Proved Cholera to be a Waterborne Illness
- Ghost Map is a literary account of his epidemiological investigation
- Concurrent epidemic in Italy in 1854
- Lead to identification of Vibrio Cholera organism by Filippo Pacini, a florence physician
- Snow was also a proponent of Anesthesia in childbirth
- Knighted by Queen Victoria on birth of seventh child
- Characteristics
- Vibrio Cholera is a facultative Anaerobic Gram Negative Rod in Vibrionaceae family
- All Vibrio genus Bacteria are curved (crescent shaped) and motile with a single polar flagellum
- Organism survival
- Not viable in pure water (stable in salt water)
- Survives up to 24 hours in sewerage
- Survives in impure water with organics for 6 weeks
- Withstands freezing for 3-4 days
- Readily killed by drying, heat, or disinfectants
- Pathogenesis
- Incubation: 4 hours to 5 days (average 1-2 days)
- Causes Toxigenic, Secretory Diarrhea (similar but more severe than Enterotoxigenic E. coli or ETEC)
- Enterotoxin adheres to intestinal epithelial cell (but does not invade)
- Severe fluid loss occurs in Small Bowel
- Large Intestine is overwhelmed by large fluid volume
- Unable to reabsorb majority of fluid losses
- Results in profuse, rice-water Diarrhea (up to 1 Liter/hour)
- Cholera Enterotoxin (Choleragen)
- Similar to Heat Labile (LT) toxin of Enterotoxigenic E. coli (ETEC)
- B-Subunits (5)
- Bind GM1 gangliosides on intestinal cell membranes
- A-Subunits (2)
- Acts at GTP-binding Protein (ADP-ribosylation)
- Activates membrane associated adenylate cyclase, converting ATP to cAMP
- Increased cAMP levels induce Sodium chloride (NaCl) secretion, and inhibit its reabsorption
- Results in osmotic water losses (as well as Electrolytes, e.g. bicarbonate and Potassium)
- Transmission
- Large infectious dose needed to cause disease
- Fecal contamination of food or water
- Waterborne Illness (most common)
- Foodborne Illness
- Heavily soiled hands or utensils
- Biological Weapon
- Infective aerosol dose: 10-500 organisms
- Severe Dehydration
- Hypovolemia to shock
- Manifestations of Electrolyte disturbance (e.g. Hypokalemia, Hypomagnesemia)
- Usual duration: 1 week
- Death may occur due to severe Dehydration if untreated
- Mortality rates approach 50% from Dehydration without aggressive Fluid Replacement
- Mortality 0.2% with aggressive rehydration (see below)
- See Acute Diarrhea
- Enteric Pathogens Nucleic Acid Test Panels
-
Stool microscopy
- Darting, motile short curved Gram Negative Rods
- No or minimal Fecal Occult Blood
- No or minimal Fecal Leukocytes
- Other microscopy modalities
- Darkfield microscopy
- Phase contrast microscopy
- General
- See Oral Rehydration Therapy
- Cholera has a high mortality, not via invasive disease, but via severe Dehydration
- Fluid and Electrolyte replacement
- Aggressive fluid and Electrolyte replacement is the key to effective management (drops mortality from 50% to 0.2%)
- Lactated Ringers is preferred crystalloid if IV hydration is required
- Replace Electrolytes (e.g. Potassium)
- Indication: Moderate to severe disease
- Adult Preparations
- Tetracycline 500 mg four times daily for 3 days
- Doxycycline 300 mg x1 dose or 100 mg bid for 3 days
- Azithromycin 500 mg orally daily for 3 days (or 1 g for 1 dose)
- Erythromycin 250 mg orally three times daily for 3 days
- Ciprofloxacin 1 g orally for 1 dose
- Child Preparations
- Azithromycin 10 mg/kg/day orally daily for 3 days
- Erythromycin 30 mg/kg/day orally divided three times daily for 3 days
- References
- Gilbert (2016) Sanford Guide, accessed 9/12/2016
-
Water Disinfection
- Dry heat at 117 degrees C (steam or boiling)
- Short exposure to disinfectants
- Water chlorination
- Good Hygiene
- Frequent Hand Washing
- Exclusive use of safe water and food
-
Licensed killed Cholera Vaccine
- Indicated during epidemics
- Efficacy: 50-86% protection lasts only 6 months
- Vaccine schedule
- Initial Doses: 0 and 4 weeks
- Booster Doses: every 6 months
- References
- Indicators of severe disease and worse outcomes
- Difficult access to medical services
- Blood Type O (45% of U.S. persons)
- Low gastric acidity
- Antacid therapy
- Partial gastrectomy
- CDC Cholera
- WHO Cholera