Exam Study Guide - Cholera, Influenza, HIV/AIDS, Plagues without Germs

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Published on 26 Feb 2011
School
UTSC
Department
Health Studies
Course
HLTB21H3
Cholera
Until the 19th century
MiasmatistsContagionists
Pettenkofer (1818 1901)
-steadfastly refused to believe in the
germ theory
-drunk a vial of bacteria contaminated
water
Disease caused by bad vapors
Believed in the germ theory
announced by Pasteur (1862)
Koch and Hansen
Diseases spread from person to
person by an infectious agent
Epidemiology
History of cholera is described as the history of pandemics
7 pandemics
1) 1816 1821: originated in India (River Ganges) and was spread by mainly by British
troops, headquarters in Bengal
2) Second pandemic: 1829 1851: more widespread, reaching Europe, Canada, and the
US
-1831 mortality of 13% in Cairo, Egypt
-1832 3: 60,000 death in England disease known as King Cholera
-In 1849 called Americas greatest scourge
3) 1852 1859: Scientific advances in understanding Cholera
4) 1863 1873
5) 1881 1896: hygienic measures stopped its spread to N America
6) 1899 1923: for the most part missed the western hemisphere
7) 1961 - ongoing
Series of epidemics:
-1961: Celebes Islands, Asia, Middle East
-1992: aboard a flight from S America to the US
-1990s: 200,000 in SE Asia
-1994: Zaire, killed 50,000 Rwandan refugees in 21 days
-2000: Africa
Etiology
During the 5th epidemic (1883)
Koch dispatched to Egypt to isolate the microbe
Able to see the bacteria in feces of 12 patients
Vibrio cholerae (due to its vibrating wiggles)
Incubation period few hours to 5 days
139 different serogroups
V. cholerae must itself be infected with two viruses:
-One has a gene that codes for the cholera toxin
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-Other must have a gene that codes for the receptor that allows the toxin-coding virus
to enter the bacterium
Infection with Cholera
Trillion V. cholerae excreted each day
Indirect transmission: fecal oral route of transmission
-Bacteria can survive on food for up to 5 days at ambient temperatures, and up to 10
days at 5-10 C
-Often found in the aquatic environment
Stomach gastric juice is lethal to V. cholerae
Low stomach acidity implies high susceptibility to cholera
Bacteria may become dormant in between epidemics
Clinical Manifestations
Severe diarrhea
Vomiting
Convulsions
Muscle cramps
Death sometimes within hours
90% of cases are mild or moderate severity
Less than 10% of ill persons develop typical cholera with severe dehydration
Diagnosis and Treatment
Dark-field or phase-contrast microscopy
1800s, a series of treatments
1832 rehydration therapy
Food-based ORT
Antibiotics shorten the course of the disease, and reduce the severity of the
symptoms
Underlying Causative Factors
Urbanization
Industrialization
Population growth
Wastewater effluents
Residential crowding
Privies
Closed working environments
Lack of hygiene
Social Disruption
1832 high mortality in Liverpool, England
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Prompted the cholera riots’ mainly directed at physicians
Victims went into hiding
Fear of bodies being sold
Outcome
Sanitary maps
Improvements in public health
-Paving roads
-Cleaner streets
-Carrying off wastes
Epidemiologic studies
John Snow (1813 1858)
Father of modern epidemiology
1849 traced an outbreak in London to two companies supplying water
1854 Grand Experiment - Investigation of London's Broad Street pump outbreak
Compared water-borne cholera cases in two regions of the city
Discovered that broken pipe contaminated water source and was behind the
London's deadly cholera epidemic of 1854
Cholera carried by WATER
When the pump was inactivated, the epidemic ceased
Cholera was a disease carried by water and not air
Supported by the work of Louis Pasteur and Koch on the germ theory 35 years later
Prevention
Sterilization
Sewage
Sources
Water purification
Sensitive surveillance and prompt reporting
SUMMARY
Important contribution learned from the cholera pandemics:
I. Etiology of the disease
II. Concepts of contagion
III. Development of sanitation procedures and techniques
IV.Development of public health policies and institutions
V.Developments in scientific field of study epidemiology, medical geography
VI. Development in therapy
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Document Summary

 pettenkofer (1818 1901) steadfastly refused to believe in the germ theory drunk a vial of bacteria contaminated water.  believed in the germ theory" announced by pasteur (1862)  diseases spread from person to person by an infectious agent.  history of cholera is described as the history of pandemics.  7 pandemics: 1816 1821: originated in india (river ganges) and was spread by mainly by british troops, headquarters in bengal, second pandemic: 1829 1851: more widespread, reaching europe, canada, and the. 1831 mortality of 13% in cairo, egypt. 1832 3: 60,000 death in england disease known as king cholera". 1992: aboard a flight from s america to the us. 1994: zaire, killed 50,000 rwandan refugees in 21 days.  koch dispatched to egypt to isolate the microbe.  able to see the bacteria in feces of 12 patients.  vibrio cholerae (due to its vibrating wiggles)  incubation period few hours to 5 days.