Chapter 7 & 8 Epidemiology and Communicable Diseases

Question 1

WHO (World Health Organization) Epidemiology Definition

Answer 1

The study of the distribution and determinants of health-related states or events (including
disease), & the application of this study to the control of diseases and other health problems

Question 2

What is the purpose of epidemiology?

Answer 2

Monitor the health of the population

Identify the determinants of health and disease in
communities

Investigate and evaluate interventions to prevent disease and maintain health

Question 3

Endemic

Answer 3

Habitual presence of disease in particular geographic area

Question 4

Epidemic

Answer 4

Occurrence of disease in excess of what is normally expected

Question 5

Pandemic

Answer 5

Global epidemic

Question 6

Epidemiologic Triad: Host

Answer 6

Age, sex, genetics

Question 7

Epidemiologic Triad: Agent

Answer 7

Bacteria, virus, alcohol

Question 8

Epidemiologic Triad: Environment

Answer 8

Humidity, access to nutritious food, crowding

Question 9

Example of Epidemiologic Triad in Infectious Diseases

Answer 9

Infectious Disease: Chickenpox

Host: Age, immune system

Vector

Agent: Varicella zoster

Environment: Proximity to other kids (in school); season

Question 10

Example of Epidemiologic Triad in Injuries

Answer 10

Ex) Injury related to Motor Vehicle Crash
- Host: Age
- Vector
- Agent: Energy transfer involved in impact
- Environment: Speed, texting, alcohol, time of day

Question 11

Web of Casuality

Answer 11

Recognizes the complex interrelationships of many interacting factors
- Can be subtle
- Either increase or decrease the risk for disease or risk

Relationships are sometimes mutual w/ lines of causality going in both directions

Question 12

Immunity

Answer 12

A host’s ability to resist a particular infectious disease-causing agent

Question 13

Passive Immunity

Answer 13

Transfer of immunity from one person to another
Ex) Breastfeeding

Question 14

Active Immunity

Answer 14

Immunizations
Antibodies develop in response to illness

Question 14

Cross-immunity

Answer 14

Immunity to one agent provides immunity to a related
agent

Question 15

Herd Immunity

Answer 15

The resistance of a group of people to an attack by disease to which a large proportion of the members of the group are immune

Question 16

How does a population acquire herd immunity?

Answer 16

Natural infection & vaccination

When enough of the population is immune, even those who are not immunized are protected

Question 17

Reproduction Number (R0)

Answer 17

Pronounced “R-naught”

The average number of people infected in a completely susceptible population

Reflects how efficiently the disease is transmitted
Ex) Measles R0 is between 12 and 18

Question 18

R Effective (Rt)

Answer 18

Current reproduction number

Takes into account current susceptibility in the population

Question 19

Risk

Answer 19

Probability that a disease or unfavorable health
condition will develop

Directly influenced by biology, environment, lifestyle,
and system of health care

Question 20

Risk Factors

Answer 20

Negative influences

Things that are associated with increased likelihood of
the disease/health outcome

Question 21

Population at Risk

Answer 21

Collection of people among whom a health problem has the possibility of developing because certain influencing factors are present or absent or because there are modifiable risk factors

Question 22

Relative Risk (RR)

Answer 22

Measurement of relative risk ratio: incidence rate in exposed group/incidence rate in unexposed group

Risk of disease same with or without risk factor 1:1
considered relative risk of 1.0
- Relative risk > 1.0 indicates greater likelihood of acquiring disease

Interpretation:
Ex) Relative risk of 2.5 means that exposed group is 2.5 times more likely to acquire the disease than the unexposed group

Question 23

How to Calculate RR Ratio

Answer 23

RR = Incidence in exposed group/ Incidence rate in
unexposed group

a (exposed & has disease)/a+b (exposed w/ no disease) divided by c(not exposed has disease)/c+d (not exposed w/ no disease)