Disease Detectives – Reference Sheet
Clinical Approach – primary role is diagnosis and treatment of illness in individuals, preventive medicine
Public Health Approach – primary role is in control and prevention of disease in populations or groups of individuals
clinical care: prevention, treatment, and management of illness and the preservation of mental and physical well-being through the
services offered by medical and allied health professions; also known as health care.
determinant: factor that contributes to the generation of a trait.
epidemic or outbreak: occurrence in a community or region of cases of an illness, specific health related behavior, or other healthrelated event clearly in excess of normal expectancy. Both terms are used interchangeably; however, epidemic usually refers to a larger
geographic distribution of illness or health-related events.
health outcome: result of a medical condition that directly affects the length or quality of a person’s life.
Health Determinants · Genes and biology · Health behaviors · Social and societal characteristics · Access to and use of health services
and medical care
Epidemiology – the disease detectives who work to solve public health issues, the study of the distribution and determinants of healthrelated states or events in specified populations, and the application of this study to the control of health problem ·
Purposes of Epidemiology in Public Health Practice
1. Determine the agent, host, and environmental factors that affect health
2. Determine the relative importance of causes of illness, disability, and death
3. Identify those segments of the population that have the greatest risk from specific causes of ill health
4. Evaluate the effectiveness of health programs and services in improving population health ·
Types of disease agents – biologic, physical, and chemical
Steps in Solving Health Problems
Step 1-Collect Data – Surveillance, determine Time/Place/Person triad
Step 2- Assessment- Inference
Step 3- Hypothesis testing – Determine how and why
Step 4- Action-Intervention
Descriptive Epidemiology involves identifying to the time, place, and the person involved in the onset of the healthrelated event.
Analytical Epidemiology is mainly concerned with finding the causes of the health-related event and to identify the interventions of
the health problem.
· In an Experimental Study, the investigators can control certain factors within the study from the beginning. An example of this type is
a vaccine efficacy trial that might be conducted by the National Institutes of Health. In such a trial, the investigators randomly control
who receives the test vaccine and who does not among a limited group of participants; they then observe the outcome to determine if
it should to be used more widely.
· In an Observational Study, the epidemiologist does not control the circumstances. These studies can be further subdivided into
descriptive and analytic. o In a Descriptive Study, the epidemiologist collects information that characterizes and summarizes the health
event or problem. o In the Analytic Study, the epidemiologist relies on comparisons between different groups to determine the role of
different causative conditions or risk factors.
Basic Epidemiology Terms – Disease Frequency
Endemic – disease or condition present among a population at all times
Outbreak – (localized epidemic) – more cases of a particular disease than expected in a given area or among a specialized group of
people over a particular period of time.
Epidemic – large numbers of people over a wide geographic area affected.
Pandemic -An epidemic occurring over a very wide area (several countries or continents) and usually affecting a large proportion of the
population.
Cluster –an aggregation of cases over a particular period esp. cancer & birth defects closely grouped in time and space regardless of
whether the number is more than the expected number. (often the expected number of cases is not known.)
Sporadic – a disease that occurs infrequently and irregularly
1. Agent - a microbial organism with the ability to cause disease
2. Reservoir - a place where agents can thrive and reproduce
3. Portal of exit - a place of exit providing a way for an agent to leave the reservoir
4. Mode of transmission - method of transfer by which the organism moves or is carried from one place to another
5. Portal of Entry - an opening allowing the microorganism to enter the host
6. Susceptible host – a person who cannot resist a microorganism invading the body, multiplying and resulting in infection
Characteristics of the Elements
vector - an animate intermediary in the indirect transmission of an agent that carries the agent from a reservoir to a susceptible host.
An organism that transmits the infection as a mosquito transmits the malaria protozoans.
· fomite - a physical object that serves to transmit an infectious agent from person to person. A comb infested with one or more head
lice would be a fomite or the dust particles containing infectious cold virus that remain after droplets of infected saliva are coughed
into the air.
· zoonosis - An infectious disease that is transmissible from animals to humans.
· Microbes which can be infectious agents include bacteria, viruses, fungi, protozoa, algae, parasitic worms, and other pathogenic
agents as prions.
· Persons more vulnerable to becoming susceptible hosts include the young, the elderly, and people with weakened immune systems.
· Environments which bring the agent and host together might involve such things as contaminated food that is ingested, an
environment that allow a vector to introduce the agent into the host as a mosquito bite, air that allow an agent to be inhaled by a host
or agents spread by contact between two people.
· Sometimes there are organisms as insects, arthropods, or even mammals as dogs or bats who can act as vectors (organisms who
allow the infecting agent to thrive, reproduce, and then act as the mode of transmission)
· Infectious dose - the amount of pathogen (measured in number of microorganisms) required to cause an infection in the host.
Usually it varies according to the pathogenic agent and the consumer's age and overall health.
· Period of communicability - the period when you are infectious and can spread your germs (whether bacteria, viruses, or parasites)
to an uninfected person
· Control Methods regarding the Susceptible Host
o Vaccination
o Chemoprophylaxis – drugs given to exposed and susceptible hosts
o Maintaining a healthy life style
o Limiting exposure to sources of infection
o Personal protective equipment
Types of Prevention Strategies
· Level of Prevention
o Primordial - Measures designed to avoid the development of risk factors in the first place, early in life – example- many adult health
problems (e.g. obesity, hypertension) develop in childhood because this is when lifestyles are formed so developing healthy lifestyles is
essential.
o Primary - Promote general health and avoid risk factors for disease – examples include immunization against disease, maintaining a
healthy diet and exercise regimen as well as utilizing protective measures to prevent susceptibility and presymptomatic disease
o Secondary - Early detection and timely treatment – examples include treatment of hypertension to avoid cardiovascular diseases and
cancer screening
o Tertiary -Rehabilitation and prevention of further disease or disability – examples include surgical procedures that halt the spread or
progression of disease
Primary Prevention Approaches
Population-Based Approach: · Preventive measure widely applied to an entire population (public health approach) · Strive for small
absolute change among many persons · Must be relatively inexpensive and non-invasive
High-Risk Approach: · Target group of individual at high risk · Strive for strong risk factor control · Often times requires clinical action to
identify the high risk group and to motivate risk factor control.