Unit 01: Foundations of Health & Disease Transmission

Question 1

What is epidemiology?

Answer 1

the study of the frequency, distribution and determinants of health and disease in populations, and the application of this study to control health problems.

Question 2

What is etiology?

Answer 2

the cause, set of causes, or manner of causation of a disease or condition.

Question 3

What is primary prevention?

Answer 3

an action taken to prevent the development of a disease in a person who is well and does not (yet) have the disease in question.
- The ultimate goal of prevention.

Question 4

What is secondary prevention?

Answer 4

• involves identifying people in whom a disease process has already begun but who have not yet developed clinical signs and symptoms of the illness.
• The goal is to detect the disease earlier than it would have been detected with usual care.

Question 5

What is tertiary prevention?

Answer 5

• denotes preventing complications in those who have already developed signs and symptoms of an illness and have been diagnosed (i.e., people who are in the clinical phase of their illness).

Question 6

Therapy involves what two types of prevention?

Answer 6

secondary and tertiary

Question 7

What is the preclinical phase of an illness?

Answer 7

The point in a diseases progession in which the disease is had, but no symptoms are present.

Question 8

What are the three classifications of prevention?

Answer 8

• primary
• secondary
• tertiary

Question 9

What are the two main approaches to prevention?

Answer 9

1. population-based approach
2. high-risk approach

Question 10

What is the population-based approach to prevention?

Answer 10

• in which a preventive measure is widely applied to an entire population.
• Must be relatively inexpensive and noninvasive.
• Can be considered public health approaches.

Question 11

What is the high-risk approach to prevention?

Answer 11

• in which you target a high-risk group with the preventive measure.
• may be more expensive and may be more invasive or inconvenient.
• require a clinical action to identify the high-risk group to be targeted.

Question 12

What is the epidemiological approach?

Answer 12

• The practice of medicine is dependent on population data.
• The process of diagnosis, prognosis, and selection of appropriate therapy are all population based.

Question 13

How does the epidemiologist proceed to identify the cause of a disease?

Answer 13

1. determine whether an association exists between exposure to a factor (e.g., an environmental agent) or a characteristic of a person (e.g., an increased serum cholesterol level) and the presence of the disease in question.
2. try to derive appropriate inferences about a possible causal relationship from the paerns of the associations that have been previously found.

Question 14

Who is Ignáz Semmelweis? What did he do?

Answer 14

• Identified the importance of handwashing and sterility in the prevention of childbed fever (major cause of death among women shortly after childbirth).
• Failure to gain traction initially indicates the need for clearly presenting supporting scientific evidence for a proposed intervention, the need for implementation of the proposed intervention to be perceived as feasible and cost-effective, and the need to lay the necessary groundwork for the policy, including garnering professional as well as community and political support.

Question 15

Who is Edward Jenner? What did he do?

Answer 15

• Performed the first “vaccination” in 1796 by infecting people with the cowpox virus (aka vaccinia virus) in order to prevent smallpox.

Question 16

Who is John Snow? What did he do?

Answer 16

• believed that cholera was transmitted through contaminated water.
• proved it is not always necessary to know every detail of the possible pathogenic mechanisms to prevent disease.

Question 17

Who is James Lind? What did he do?

Answer 17

• the “father of nautical medicine” after conducting the first-ever documented randomized controlled trial to identify the cure for scurvy.

Question 18

Who is Sir Percival Pott? What did he do?

Answer 18

• one of the earliest accounts of a cause and effect linkage for an occupational carcinogen (chimney-sweeper’s cancer aka soot-wart)

Question 19

What happened in the world of epidemiology in the 19th Century?

Answer 19

• John Snow and the Broad St. pump
• Communicable disease epidemiology

Question 20

What happened in the world of epidemiology in the 1950s?

Answer 20

• Chronic disease epidemiology
• Seroepidemiology

Question 21

What happened in the world of epidemiology in the 1980s?

Answer 21

• Clinical epidemiology
• Pharmacoepidemiology

Question 22

What happened in the world of epidemiology in the 1990s?

Answer 22

• Molecular epidemiology
• Genetic epidemiology
• Social epidemiology

Question 23

What is disease transmission?

Answer 23

• results from an interaction of the host (a person), the agent (e.g., a bacterium), and the environment (e.g., polluted air)
• an interaction of genetic, behavioral, and environmental factors, with the proportions differing for different diseases.

Question 24

What are the components of the epidemiologic triad?

Answer 24

1. agent
2. host
3. environment

Question 25

What are the two broad means of disease transmission? How do they work?

Answer 25

1. directly (transmitted from person to person via direct contact)
2. indirectly (through a common vehicle such as a contaminated air or water supply or by a vector such as a mosquito)

Question 26

What is a vector?

Answer 26

an insect, or any living carrier, that transports an infectious agent from an infected individual to a susceptible individual, or its food, or immediate surroundings.

Question 27

What are the two types of disease transmission?

(not direct and indirect)

Answer 27

1. Horizontal transmission
2. Vertical transmission

Question 28

What is vertical transmission?

Answer 28

Transmission of an infectious agent from mother to embryo, fetus or baby before, during, or just after pregnancy.

Question 29

What is horizontal transmission?

Answer 29

Transmission of an infectious agent between members of the same species through direct or indirect contact.

Question 30

What is a clinical diease?

Answer 30

• characterized by signs and symptoms.
• only a clinical illness is readily apparent.

Question 31

What is a nonclinical disease?

Answer 31

• a disease that is nonapparent.

Question 32

What are the four types of nonclinical disease?

Answer 32

1. Preclinical disease
2. Subclinical disease
3. Persistent (chronic) disease
4. Latent disease

Question 33

What’s a Latent disease?

Answer 33

• An infection with no active multiplication of the agent, as when viral nucleic acid is incorporated into the nucleus of a cell as a provirus.
• only the genetic message is present in the host, not the viable organism.

Question 34

What’s a Preclinical disease?

Answer 34

• Disease that is not yet clinically apparent but is destined to progress to clinical disease.

Question 35

What’s a Subclinical disease?

Answer 35

• Disease that is not clinically apparent and is not destined to become clinically apparent.
• often diagnosed by serologic (antibody) response or culture of the organism.

Question 36

What’s a Persistent (chronic) disease?

Answer 36

• A person fails to “shake off” the infection, and it persists for years, at times for life.
• the manifestation of symptoms is often many years after an infection was thought to have been resolved.

Question 37

What’s a carrier?

Answer 37

• an individual who harbors the organism but is not infected as measured by serologic studies (no evidence of an antibody response) or shows no evidence of clinical illness.
• infect others, although the infectivity is generally lower than with other infections.
• may be of limited duration or may be chronic.

Question 38

What’s an Endemic?

Answer 38

the habitual presence of a disease within a given geographic area.

Question 39

What’s an Epidemic?

Answer 39

the occurrence of a disease in a community or region of a group of illnesses of similar nature, clearly in excess of normal expectancy and derived from a common or a propagated source

Question 40

What’s an epidemic curve?

Answer 40

• the distribution of the times of onset of the disease.

Question 41

What’s a Pandemic?

Answer 41

a worldwide epidemic

Question 42

What does sporadic mean in terms of a disease?

Answer 42

a disease occurs only occasionally in a population.

Question 43

What is Herd Immunity?

Answer 43

• the resistance of a group of people to an attack by a disease to which a large proportion of the members of the group are immune.
• If a large percentage of the population is immune, the entire population is likely to be protected, not just those who are immune.
• For herd immunity to exist, the disease agent must be restricted to a single host species within which transmission occurs, and that transmission must be relatively direct from one member of the host species to another.

Question 44

What is Innate Immunity?

Answer 44

• You are born with this type of “natural” immunity.
• It is not specific to any antigen, so it provides an immediate response to foreign invaders in the body.

Question 45

What is Acquired Immunity?

Answer 45

• You can acquire immunity naturally or artificially, and this acquisition can be active or passive.

Question 46

What are the four types of acquired immunity?

Answer 46

1. Naturally acquired active immunity
2. Artificially acquired active immunity
3. Naturally acquired passive immunity
4. Artificially acquired passive immunity

Question 47

What is Artificially acquired passive immunity?

Answer 47

• a short-term immunization with an injection of antibodies, such as gamma globulin, that are not produced by the recipient’s cells.
• assists in the immune system fighting off infection.

Question 48

What is Naturally acquired passive immunity?

Answer 48

• occurs during pregnancy, when certain antibodies are passed from the mother to the fetus.

Question 49

What is Artificially acquired active immunity?

Answer 49

• can be induced by a vaccine, a substance that contains the antigen.
• a vaccine stimulates a primary response against the antigen without causing symptoms of the disease.

Question 50

What is Naturally acquired active immunity?

Answer 50

• occurs when the person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response.

Question 51

What is an Incubation period? What does it represent?

Answer 51

• the interval from receipt of infection to the time of onset of clinical illness (the onset of recognizable symptoms).
• reflects the time needed for the organism to replicate sufficiently until it reaches the critical mass needed for clinical disease to result, and relates to the site in the body at which the organism replicates

Question 52

What is health?

Answer 52

A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.

Question 53

What is Disease?

Answer 53

a derangement in the function of the whole body of the host or any of its parts (a physiological/psychological dysfunction).

Question 54

What is a zoonotic disease?

Answer 54

any disease and/or infection that is naturally transmissible from vertebrate animals to man.

Question 55

What does “Infected” refer to?

Answer 55

a host that is invaded by microorganisms, the organisms multiply, and the host’s immune system responds.

Question 56

What does “Diseased” refer to?

Answer 56

an infection that causes clinical signs/symptoms.

Question 57

What is the Stage of Susceptibility?

Answer 57

• A susceptible individual/host is exposed to an amount of an agent that is sufficient enough to cause disease to occur.

Question 58

Stage of Pre-Symptomatic Disease

Answer 58

• As time progresses from the point of exposure/infection, changes in the pathology of the infected host will begin.
• No signs or symptoms of the disease are present, but the pathologic process is detectable.

Question 59

What is the Stage of Clinical Disease?

Answer 59

• As time progresses, more significant changes occur in the body, resulting in the presentation of visible/clinical signs and symptoms of the disease.

Question 60

What is the Stage of Disability or Recovery?

Answer 60

Once the clinical form of disease has occurred, there is a period of time when an individual might be treated, after which the outcome (disability or recovery) will occur.