HLTH 485
HLTH 485 ELISCAR CASE STUDY ASSIGNMENT 2.
CASE STUDY ASSIGNMENT INSTRUCTIONS
OVERVIEW
In order to master epidemiological concepts acquired in this course, it is imperative that you
understand how disease outbreak investigations work. You will be able to navigate a real-life
outbreak and solve important questions in relations to the case.
INSTRUCTIONS
You will find the case study titled: “Case Study I: Snow on Cholera” in the appendix I section in
the back of the textbook. Read the case study and answer all the questions below. You must use
complete sentences.
A: Observations on cholera
1. Concerning John Barnes, how was cholera communicated? What were the modes of disease
transmission? What is the correct epidemiological term for the modes of transmission that were
identified?
In the case of John Barnes, the disease is transmitted several ways, person to person transmission,
fomite transmission and environmental contamination. The epidemiologic terms would be direct
transmission, fomite transmission and the incubation period.
2. How long is a fortnight?
Fortnight is used to describe two weeks.
3. In the examples or circumstances presented, what were the various modes of transmission stated
or at least alluded to? Which were correct? Which were incorrect and why? What role did
personal hygiene and sanitation (including food preparation and hand washing) play in the
transmission of the disease and continuation of an outbreak?
Several modes of cholera transmission are highlighted, including direct person-to-person contact,
as seen with Mrs. Gore, who contracted cholera after attending to her son. Fomite transmission is
illustrated by John Barnes' case, where cholera spread through contaminated clothing. The
ingestion of contaminated water or food is another key mode, as demonstrated by incidents in
Thomas Street, Horsleydown, and Manchester, where sewage polluted water wells. In
environments with poor sanitation, involuntary contamination, such as exposure to feces,
accelerates the spread of the disease. Correct transmission modes include person-to-person via
bodily fluids, fomite transmission, and contaminated water supplies. Early theories suggesting
airborne "effluvia" as the cause of cholera were incorrect, as the disease spread through ingestion
of contaminated material, not via the air.
1. Several instances of causal association were presented or alluded to in the examples
presented in the case. List the various instances of association you can identify from the examples
or situations presented in the case. What role did social class, poverty, and housing arrangements
play in association? What role did water play in association?
, HLTH 485
- Several cases illustrate different modes of cholera transmission. In John Barnes' case, cholera
spread through contaminated clothing and linens. A nurse in Liverpool contracted the disease
after attending to a patient and transmitted it to others, demonstrating person-to-person
transmission. In Horsleydown and Salford, contaminated water from sewage leaks caused
widespread cholera outbreaks. The Tockwith case showed how cholera spread through close
contact with contaminated linens or feces due to poor sanitation. In Ilford, a family using clean
water avoided cholera, while those using contaminated water became ill. Cholera spread more
rapidly in poorer, overcrowded areas with poor sanitation. Access to clean water and proper
sanitation was key in determining whether individuals or communities contracted cholera.
Additionally, improper food handling in unsanitary conditions contributed to the disease's spread.
4. Describe the disease cholera as presented in the Snow case. Describe cholera as it is known
today.
- John Snow hypothesized that cholera was spread through contaminated water, particularly
water tainted by feces from infected individuals. By mapping cholera cases in London, he
identified a contaminated water pump as the source of the outbreak, providing early evidence of
waterborne transmission. Today, cholera is understood to be caused by the bacterium Vibrio
cholerae, transmitted mainly through ingestion of contaminated water or food. It causes severe
diarrhea and dehydration, and modern treatments focus on rehydration and antibiotics.
5. What hypotheses were developed by John Snow about the cause (etiology), signs and
symptoms, spread and course of the cholera disease? How do the observations and hypotheses of
Snow conform with modern understanding and knowledge of cholera?
- John Snow hypothesized that cholera was caused by contaminated water, not by "miasma" (bad
air), and his work tracing cholera outbreaks in London supported this theory. Cholera symptoms
include diarrhea, vomiting, and severe dehydration, which align with Snow's observations and the
modern understanding of the disease's rapid fluid loss, often leading to death without treatment.
Snow believed cholera spread quickly once a community’s water supply was contaminated,
matching today's knowledge of waterborne transmission. He also noted a short incubation period
of 24-48 hours, consistent with the rapid progression of cholera.
6. What is different about those who develop cholera compared with those who do not?
- Susceptible individuals are those who consume contaminated water or food, or come into
contact with cholera patients or their contaminated belongings. Resistant individuals are those
who avoid contaminated water, maintain good hygiene, and do not have close contact with
infected people, reducing their risk of contracting cholera.
7. What epidemiological phenomenon can be observed in the Locksbrook, near Bath, example?
The Locksbrook case highlights an epidemiological phenomenon known as environmental
contamination. The contamination of the well water by cesspool drainage led directly to a cholera
HLTH 485 ELISCAR CASE STUDY ASSIGNMENT 2.
CASE STUDY ASSIGNMENT INSTRUCTIONS
OVERVIEW
In order to master epidemiological concepts acquired in this course, it is imperative that you
understand how disease outbreak investigations work. You will be able to navigate a real-life
outbreak and solve important questions in relations to the case.
INSTRUCTIONS
You will find the case study titled: “Case Study I: Snow on Cholera” in the appendix I section in
the back of the textbook. Read the case study and answer all the questions below. You must use
complete sentences.
A: Observations on cholera
1. Concerning John Barnes, how was cholera communicated? What were the modes of disease
transmission? What is the correct epidemiological term for the modes of transmission that were
identified?
In the case of John Barnes, the disease is transmitted several ways, person to person transmission,
fomite transmission and environmental contamination. The epidemiologic terms would be direct
transmission, fomite transmission and the incubation period.
2. How long is a fortnight?
Fortnight is used to describe two weeks.
3. In the examples or circumstances presented, what were the various modes of transmission stated
or at least alluded to? Which were correct? Which were incorrect and why? What role did
personal hygiene and sanitation (including food preparation and hand washing) play in the
transmission of the disease and continuation of an outbreak?
Several modes of cholera transmission are highlighted, including direct person-to-person contact,
as seen with Mrs. Gore, who contracted cholera after attending to her son. Fomite transmission is
illustrated by John Barnes' case, where cholera spread through contaminated clothing. The
ingestion of contaminated water or food is another key mode, as demonstrated by incidents in
Thomas Street, Horsleydown, and Manchester, where sewage polluted water wells. In
environments with poor sanitation, involuntary contamination, such as exposure to feces,
accelerates the spread of the disease. Correct transmission modes include person-to-person via
bodily fluids, fomite transmission, and contaminated water supplies. Early theories suggesting
airborne "effluvia" as the cause of cholera were incorrect, as the disease spread through ingestion
of contaminated material, not via the air.
1. Several instances of causal association were presented or alluded to in the examples
presented in the case. List the various instances of association you can identify from the examples
or situations presented in the case. What role did social class, poverty, and housing arrangements
play in association? What role did water play in association?
, HLTH 485
- Several cases illustrate different modes of cholera transmission. In John Barnes' case, cholera
spread through contaminated clothing and linens. A nurse in Liverpool contracted the disease
after attending to a patient and transmitted it to others, demonstrating person-to-person
transmission. In Horsleydown and Salford, contaminated water from sewage leaks caused
widespread cholera outbreaks. The Tockwith case showed how cholera spread through close
contact with contaminated linens or feces due to poor sanitation. In Ilford, a family using clean
water avoided cholera, while those using contaminated water became ill. Cholera spread more
rapidly in poorer, overcrowded areas with poor sanitation. Access to clean water and proper
sanitation was key in determining whether individuals or communities contracted cholera.
Additionally, improper food handling in unsanitary conditions contributed to the disease's spread.
4. Describe the disease cholera as presented in the Snow case. Describe cholera as it is known
today.
- John Snow hypothesized that cholera was spread through contaminated water, particularly
water tainted by feces from infected individuals. By mapping cholera cases in London, he
identified a contaminated water pump as the source of the outbreak, providing early evidence of
waterborne transmission. Today, cholera is understood to be caused by the bacterium Vibrio
cholerae, transmitted mainly through ingestion of contaminated water or food. It causes severe
diarrhea and dehydration, and modern treatments focus on rehydration and antibiotics.
5. What hypotheses were developed by John Snow about the cause (etiology), signs and
symptoms, spread and course of the cholera disease? How do the observations and hypotheses of
Snow conform with modern understanding and knowledge of cholera?
- John Snow hypothesized that cholera was caused by contaminated water, not by "miasma" (bad
air), and his work tracing cholera outbreaks in London supported this theory. Cholera symptoms
include diarrhea, vomiting, and severe dehydration, which align with Snow's observations and the
modern understanding of the disease's rapid fluid loss, often leading to death without treatment.
Snow believed cholera spread quickly once a community’s water supply was contaminated,
matching today's knowledge of waterborne transmission. He also noted a short incubation period
of 24-48 hours, consistent with the rapid progression of cholera.
6. What is different about those who develop cholera compared with those who do not?
- Susceptible individuals are those who consume contaminated water or food, or come into
contact with cholera patients or their contaminated belongings. Resistant individuals are those
who avoid contaminated water, maintain good hygiene, and do not have close contact with
infected people, reducing their risk of contracting cholera.
7. What epidemiological phenomenon can be observed in the Locksbrook, near Bath, example?
The Locksbrook case highlights an epidemiological phenomenon known as environmental
contamination. The contamination of the well water by cesspool drainage led directly to a cholera
