(Last Updated 2 January 2015)
Clinical features
- diarrhea
- vomiting (early)
- dehydration
- death
Diarrhea
- early on, fecal and malodorous
- later “rice water stool”
- painless
- non-straining
- sometimes a little cramping (like an enema)
- massive
Dehydration
- massive diarrhea — can be more than 1/5 your entire body weight in a single day!
- symptoms
- sunken eyes and cheeks
- slow “pinch response”
- rapid and weak or missing pulse
- can be diagnosed on sight!
Death caused by dehydration
- can occur in 12 hours or less
- can be treated by rehydration
Therapy
- Intravenous solutions to rehydrate after dehydration sets in
- Oral Rehydration to maintain fluid (and electrolyte) balance
- Immunity follows and is both effective and long-lasting
Rehydration to replace
- water (4 gallons a day is not a lot)
- salts (mostly sodium chloride [salt] and potassium bicarbonate)
- glucose (energy for transport and survival)
- rice water stool isotonic with plasma, so replace quart for quart
Cholera cot
- plastic cot with a hole
- calibrated bucket
- replace with “gatorade”
- orally if strong enough
- nasogastric tube if not
Antibiotic therapy
- reduces recovery time by half
- 2-3 days of diarrhea rather than 4-6 days
- untreated, a very few will become “carriers” for a few months
Infection
- Causative agent Vibrio cholerae
- Grows in humans, but also in environment
- salt water best
- “viable but non-culturable”
- association with chitin (shellfish)
- fecal-oral transmission
- contaminated water supply most common source
Incubation
- Normally requires high dose (about a billion cells) for infection
- Antacids reduce that by ten-thousand-fold!
- (Data from infecting prisoners)
Pathology
- onset of symptoms usually 12-72 hours after ingestion
- depends on dose
- Vibrio cholerae don’t invade cells, just attach to intestine
- Secrete a toxin
Cholera toxin has two parts
- an enzyme that damages the salt/water balance
- a hormone-like part that fools the cell into taking it up
- Cholera toxin inactivates the regulatory part of adenylate cyclase
- causes Chloride to be excreted into intestine (crypt cells)
- blocks uptake of sodium chloride (and water) from intestine (villus cells)
- water follows salt
Effects of water flowing into intestine
- Small intestine recycles about 9 quarts per day
- Large intestine recycles another quart or so
- Cholera overwhelms that
- Water loss is in small intestine
- Death from dehydration is rapid (shock and general collapse)
Epidemiology of Cholera
- Begins in 1817 “Asiatic Cholera”
- “Seven” pandemics since then
- We’ll look at three epidemics
- Definition of “epidemic” and “pandemic”
John Snow
On the Mode of Communication of Cholera
This is really the beginning of modern epidemiology (see assigned reading for discussion)
- by John Snow, M.D.
- Second edition, much enlarged
- 1855 (preface dated 11 December 1854)
- Reprinted in 1936
- Analysis After the Fact!
Influence of the Water Supply on the Epidemic of 1832, 1849, and 1854 in London
- Early Outbreaks
- Southwark and Vauxhall Water Co. dirty
- Lambeth Water Co. dirty
- Cholera about the same for both
- Chelsea Water Works, clean
- much less cholera
Outbreak of Aug 1853-Jan 1854
- Lambeth found new source of water
- upstream of London’s sewage outlet
- Some districts purely Southwark and Vauxhall, some purely Lambeth
- Some districts had BOTH sets of pipes on the same street!
Death rates from Cholera (by district)
- Outbreak of 1854
- Probably from the Baltic Fleet
- Look at districts supplied by BOTH on house by house basis
Differences in the water
- S&V water had 37.9 grains of salt per gallon
- Lambeth water had 0.95 grains of salt per gallon
- easy to tell apart
- Vibrio cholerae requires some salt for survival
- Lambeth, clean; S&V, dirty
Death rates from Cholera (by district)
Water Co. | Deaths/10,000 houses |
Southwark and Vauxhall | 315 |
Lambeth | 37 |
Outbreak at the Broad Street Pump
- London 1854
- “Worst outbreak ever”
- over 500 fatal cases within 250 yards of the pump
- Led him to analyze the waterworks data from the earlier outbreak
The Outbreak
- a few cases in late August
- Probably originally came in from the Black Sea Fleet
- Really began the night of Aug. 31/Sep. 1
Actual Cause of the Outbreak
- Learned by the clergyman (Henry Whitehead) after the fact
- Infant (baby Lewis) developed diarrhear on Aug 28 (dies Sept. 2)
- Mother (Sarah Lewis) soaked diapers in pails
- Emptied pails into a cesspool 3 feet from the pump
The first week (ending Sept 2) 83 cases
- all but ten were nearer the Broad St. Pump than any other
- 5 families said they preferred the water from the Broad St. Pump
- 3 were children who went to school near the pump
- 2 occurred before the real outbreak
The majority lived near the pump
- 61 known to drink from the pump
- 6 no info (whole family died)
- 6 did NOT drink from the pump directly
- may have drunk indirectly
- water in drinks (liquor) or sodas
Pump handle removed on Sept 8
- Board of Guardians of St. James’ parish on the 7th
- ended the outbreak (as did the departure of 3/4 of the residents!)
- Pump water was probably already cleared of cholera by then anyhow
- But the pump handle makes a more dramatic story
Added twist
- Baby Lewis dies on Sept. 2
- ending contamination of the well
- Thomas Lewis (father) fell ill on Sept 8
- same day as pump handle removed
- Removing pump handle did not end the outbreak, but it did prevent a second wave
- No other apartment in the house had access to the old cesspool
Lessons from the Broad Street Pump
- Almost everyone who died drank from the pump
- No question: cholera is transmitted in the water. Period.
Hamburg 1892
- Hanseatic State
- Oligarchic rule (Senate)
- No civil service
- Capitalism (Trade) rules all
Filtration of Water
- known to be effective since John Snow
- costs money, so delayed
- Altona (downstream and next to Hamburg) had filtration
The Hamburg-America Line
- transporting immigrants to America
- especially from central and eastern Europe
- A trainload of immigrants from Ukraine
- Known cholera outbreak
- Hamburg accepted them anyhow
- Cholera broke out in the warehouse where they were kept
- Shipped them to America
Cholera ships
- shipowners feared closing the port of Hamburg
- Medical officer forced American vice-consul to give clean bill of health to ships
- Several ships forced to sail back to Hamburg
- Many deaths
Hamburg vs. Altona (effects of filtration)
City | Population | Cholera cases | Cases/1000 |
Hamburg | 580,000 | 19,891 | 34 |
Altona | 143,000 | 572 | 3.9 |
Anti-contagionism
- Petenkofer and conservatism of physicians
- could not culture bacteria or use microscope
- Koch was Prussia
- Anti-contagionism was more “intuitive” and cheaper!
- Slow action on an epidemic cost thousands of lives.
Miasmatic Theory of Cholera
- Von Pettenkofer’s “experiment
- Drank a vial of pure V. cholerae (no ill effects)
- (Student [Rudolph Emmerich] did same, got cholera!)
- Three factors required
- Specific infectious element (new idea!)
- Porous soil with decaying matter in it
- Toxic substance produced by these two
Importance of Snow’s work
- Miasmatists used his spot map to support their own (less specific) theories
- General sanitation vs. specific cause
- Not really recognized until much later
- Now he is “myth” and parish committee is forgotten, especially Henry Whitehead
- Myth?