32 Questions
What theory replaced the concept of miasma in the late 19th century?
Germ theory
Who proposed the basic forms of the germ theory of disease in 1546?
Girolamo Fracastoro
Which small organisms are known as pathogens or 'germs' according to the germ theory of disease?
Bacteria
Who were the first to document the terms primary, secondary, and tertiary prevention in relation to disease prevention?
Hugh Leavell and Clark
What specific organism is mentioned in the text that can cause diseases like cholera?
Bacteria
What is the main focus of the lecture on the concept of causation?
Exploring historical development of theories of causation
In epidemiology, what is a cause most closely associated with?
The disorder of structure or function
What is disease characterized by?
Specific symptoms and signs
What is the primary aim of establishing causality in epidemiology?
Determining relationships between factors
Which theory of causation mentioned in the text involves supernatural punishment?
Theory of divine retribution
What distinguishes a cause in epidemiology from a direct result of physical injury?
Disorder of structure or function
What theory detailing the supposed makeup and workings of the human body was adopted by Ancient Greek and Roman physicians and philosophers?
Humorism
What was a key factor in the downfall of Humorism in the 1850s?
Adoption of germ theory
According to Humorism, what were the four supposed humors that made up the human body?
Flegmat, Sanguin, Coleric, Melanc
Which theory proposed that diseases were caused by a noxious form of 'bad air' known as miasma?
Miasma theory
What was believed to be protective against diseases according to the miasma theory?
'Scented air'
According to Hill's criteria, which is NOT a requirement for establishing causation?
Absence of any threshold effects in the data
What do critics of using analogy in epidemiology argue?
It implies a lack of imagination in the investigator
What does Hill suggest should happen if an intervention modifies exposure in an experiment testing causation?
There should be less disease or no disease at all
In terms of cancer deaths and smoking, what could prevent the observation of a biological gradient even if there is a causal effect?
Saturation or threshold effects
What does Hill consider essential for 'Coherence' in terms of causation?
Harmony with known natural history and biology
Which statement accurately reflects Hill's suggestion for establishing causation through analogy?
'Analogy' does not necessarily imply causation but aids in drawing parallels
Which model introduced in 1976 is also known as the Causal Pies model?
Rothman's Causal Pies
What is the term used to describe a component that appears in every pie or pathway and is essential for disease occurrence?
Necessary cause
According to Sir Austin Bradford Hill's criteria, which attribute describes the concept that true causes must exhibit strong associations?
Strength of association
In the context of epidemiology, which factor refers to extrinsic factors that affect the agent and the opportunity for exposure?
Environment
What model explores multiple causative factors, giving equal prominence to Agent, Host, and Environment in identifying determinants and relevant interventions?
Triangle of Causation
Which criterion for assessing causality asserts that associations are more likely to be causal if they are observed repeatedly by different individuals in different circumstances?
Consistency
What refers to a variety of intrinsic factors in a host that may influence exposure, susceptibility, or response to a causative agent?
Host
'An association is more likely to be causal if its strength increases as the exposure level increases' - which criterion does this statement refer to?
Biological gradient
'An individual factor that contributes to causing disease shown as a piece of a pie' - this concept is associated with which model?
Sufficient-Component Cause Model
In epidemiology, what is broadened to include chemical and physical causes of disease or injury besides infectious microorganisms?
Agent
Study Notes
Disease Causation
- Many cultures have a story about a deity exacting punishment upon previous inhabitants of their land, causing their doom (e.g. great flood, Tower of Babel, Sodom and Gomorrah)
Humorism
- A system of medicine detailing a supposed makeup and workings of the human body, adopted by Ancient Greek and Roman physicians and philosophers
- The system began to fall out of favor in the 1850s with the advent of germ theory
- It proposed that the human body consisted of four humors: phlegm, blood, yellow bile, and black bile
Miasma Theory
- An obsolete medical theory that diseases were caused by a noxious form of "bad air" or a miasma
- The theory was advanced by Hippocrates in the fourth century B.C. and accepted in ancient times in Europe and China
- It was eventually abandoned by scientists and physicians after 1880, replaced by the germ theory of disease
Germ Theory
- The currently accepted scientific theory for many diseases, stating that microorganisms (pathogens or "germs") can lead to disease
- These small organisms, too small to see without magnification, invade humans, other animals, and other living hosts
- Basic forms of germ theory were proposed by Girolamo Fracastoro in 1546 and expanded upon by Marcus von Plenciz in 1762
Web of Causation
- The epidemiologic triad or triangle model of causation, consisting of an external agent, a susceptible host, and an environment that brings the host and agent together
- Disease results from the interaction between the agent and the susceptible host in an environment that supports transmission of the agent
- The triad model is the traditional model for infectious disease, but has proven inadequate for diseases like cardiovascular disease and cancer that have multiple contributing causes
Epidemiologic Triad
- Agent: an external agent or infectious microorganism, which must be present for disease to occur
- Host: a human who can get the disease, influenced by factors such as genetic composition, nutritional and immunologic status, and psychological makeup
- Environment: extrinsic factors that affect the agent and the opportunity for exposure, including physical, biologic, and socioeconomic factors
Sufficient-Component Cause Model
- A model introduced by Rothman in 1976, where an individual factor that contributes to cause disease is shown as a piece of a pie
- The complete pie, or a sufficient cause, is composed of several component causes that may or may not overlap
- A necessary cause is a component that appears in every pie or pathway
Guidelines for Assessing Causality
- Criteria for assessing causation proposed by Sir Austin Bradford Hill in 1965:
- Strength of association
- Consistency
- Specificity
- Temporality
- Biological gradient
- Biological plausibility
- Coherence
- Experimental evidence
- Analogy
Learn about the historical development of theories of causation, characteristics of a cause, and the process of establishing causality in Epidemiology. Explore disease causation and its impact on human, animal, and plant health.
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