2. What is cholera?
– Cholera is one of the most feared clinical entities on earth. It
is a preventable, acute diarrheal disease that leads to severe
dehydration due to a massive loss of bodily fluids.
– It can lead to sunken eyes, blue-grey skin and eventually
death.
– 80% of cholera cases today can be prevented by the ingestion
of rehydration salts
4. • Cholera is a term derived from Greek khole (illness from bile) and later in the 14th
century to colere (French) and choler (English).
• In the 17th century, cholera was a term used to describe a severe gastrointestinal
disorder involving diarrhea and vomiting.
• Cholera is caused by bacteria: Vibrio cholerae, which was discovered in 1883 by
Robert Koch during a diarrheal outbreak in Egypt.
• The organism is a comma-shaped, gram-negative, aerobic bacillus whose size
varies from 1-3 mm in length by 0.5-0.8 mm in diameter.
6. – Cholera has likely been affecting humans for many centuries. Reports of cholera-like
disease have been found in India as early as 1000 AD. Outbreaks in India have been well
documented since the early 1800’s, in which hundreds of thousands of people became ill.
Many of those who got sick went on to die.
– Since 1817, there have been 7 cholera pandemics reported. The first 6 occurred from
1817-1923. The pandemics originated in Asia with subsequent spread to other continents
– The seventh pandemic began in Indonesia in 1961 and affected more countries and
continents than the previous 6 pandemics.
Spread of the disease
8. Cholera epidemics in England
– England had several outbreaks of cholera in the 19th century, the most notable being in
1854, when Dr. John Snow did a classic study in London that showed a main source of
the disease
– John Snow was already a famous anesthetist and His work on cholera has led him to be
called “The father of epidemiology”.
– John Snow mapped cases of cholera to help give him clues
about the cause.
JOHN SNOW
9.
10. – Mapping of cases led John snow to suspect water from the Broad street pump as
a cause of cholera.
– He found that those who were affected had drunk water from the pump.
– John Snow recommended the pump should not be used and that it’s handle
should be removed.
– After the handle was removed the outbreak subsided.
– The pump is still present as a landmark in London.
– Despite this there was scepticism about his findings.
Broad Street Pump
11. – He overcame this scepticism by conducting an elegant epidemiological study which
he called "The Grand Experiment"
– In The experiment, one group was supplied with water containing the sewage of
London, and, amongst it, whatever might have come from the cholera patients, the
other group having water quite free from such impurity
– He compared annual death rates from cholera in people drinking water from
different sources and found that the risk was 14 times greater (relative risk 14) in
those who drank water which was extracted from the Thames in London where there
was heavy sewage contamination.
– He concluded that cholera was spread from person to person via morbid material
from the alimentary canal of the sufferer that was then swallowed by other people
and had the power of multiplication in the body of the person it attacked.
12. – John Snow’s work led to massive public concern about contamination of
drinking water.
– Massive sanitary reform followed which prevented future epidemics of
cholera. The last epidemic was in 1866 and was much smaller than previous
epidemics
1850’s
Water Supply In London
13. Discovery of the causative agent
– Although Dr. Snow did not discover the cause of cholera, he did show how the disease
could be spread and how to stop a local outbreak.
– V. cholerae was first isolated as the cause of cholera by Filippo Pacini in 1854, but his
discovery was not widely known until Robert Koch (who also discovered the cause of
tuberculosis), working independently 30 years later, publicized the knowledge and the
means of fighting the disease
Filippo PaciniRobert Koch
14. Beliefs about the causes of cholera
– Prior to the work of John Snow people had very little concept of mechanisms of
contagion. Consequently beliefs about the causes of cholera were often bizzare.
– Supernatural causes
– The wrath of God
– Astrological causes
– Miasma - bad or malodorous air as a cause of disease.
– Pleasant or strong smelling agents (e.g. Camphor, herbs, or smoke) were thought to
be protective.
– Contagion
– Many believed that alcohol would protect against cholera.
– There was some perception that disease could be spread by contact with the patient
or contact with their clothes
15. Symptoms
– Occur 2-3 days after consumption of contaminated food/water
– Decreased skin turgor
– Sunken eyes, cheeks
– Almost no urine production
– Dry mucous membranes
– Vomiting
– Watery diarrhea consists of:
– fluid without RBC, proteins, electrolytes
– enormous numbers of vibrio cholera (107 vibrios/mL)
– Without treatment, death in 18 hours-several days
16. Treatments for Cholera
– The CDC (and almost every medical agency) recommends
rehydration with ORS (oral rehydration salts) fluids as the
primary treatment for cholera.
– For Severe dehydration- 4 drips of Ringer Lactate or, if not
available, normal saline and oral rehydration salts
17. Methods of Prevention
– Education on hygiene practices.
– Provision of safe, uncontaminated, drinking water to the people.
– Antibiotic prophylaxis to house-hold contacts of index cases.
– Vaccination against cholera to travellers to endemic countries &
during public gatherings.
