Infectious Disease Epidemiology

In our first module, we met the Thompson family and began exploring epidemiology, discussing its essentials, historical impact, and importance in public health. We initiated our hands-on investigation by monitoring symptoms and interviewing the affected individuals, setting the stage for further analysis.

Now, we will focus on infectious disease epidemiology as we continue to study the Thompson family and their town to try to identify and hopefully treat the disease responsible for everyone getting sick.

Our objective now is to identify the pathogen causing the illness.

Pinpointing this pathogen is crucial—it will shape our approach to managing and halting the disease.

In this module, we will dive into various crucial topics:

The characteristics of pathogens and their resultant diseases.
The body's defense mechanisms and when homeostasis fails.
The development of pathogens, especially regarding antibiotic resistance.
We will also examine how the disease spreads within the community.

Applying the epidemiology triangle—host, agent, environment—will help structure our investigation. Your involvement and analysis are vital as we aid the Thompson family and their community. By the end of this module, we aim to identify the pathogen and create effective treatment and prevention strategies.

Let’s collaborate to solve this epidemiological puzzle, potentially curbing the outbreak and preserving health.

questions to think about

How does the body fight off disease?
What are the steps in the disease process?
How do the components of the epidemiologic triangle interact?
How can prevention activities influence the impact of diseases?
What are the different types of immunity?
What are the different types of pathogens?
What is pathogen evolution and antibiotic resistance?
What are the different modes of disease transmission, and how do they affect the spread of infectious diseases?
How are models used to demonstrate disease transmission and evaluate the impact of timing of exposure on disease spread?
How are global and local patterns of infectious diseases analyzed while identifying key factors involved in their spread?

Words you need to know

Disease - an abnormal condition affecting the body of an organism.
Immune system - a system of biological structures and processes within an organism that protects against disease.
Direct transmission - a pathogen is transferred directly into the body of an organism.
Indirect transmission - a pathogen is transferred to an organism by an intermediate such as a fomite or vector.
Incubation period - the time elapsed between exposure to a pathogen, a chemical or radiation, and when symptoms and signs are first apparent.
Pathogen - a microorganism that causes disease in its host.
Host - the organism that is affected.
Index case - the initial patient in the population of an epidemiological investigation.
Agent - disease causing entity.
Carrier - a person or organism infected with an infectious disease agent.
Immunity - resistance of an organism to infection or disease.
Antibody - a large Y-shaped protein that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.
Antigen - a protein on the surface of a cell that induces a specific immune response.
Communicable - able to be transmitted from one to another.
Active immunity - the development of antibodies in response to stimulation by an antigen, such as from vaccines, exposure to a pathogen, or recovering from a disease.
Passive immunity - the development of antibodies from another person or source, such as given antibodies, or from mother to baby through placenta or breast milk.
Acute disease - a disease characterized by rapid onset and a short duration.
Chronic disease - a disease of long duration and generally slow progression.
Prodromal period - the period of nonspecific symptoms before a disease's real symptoms appear.
Infectious disease - disease caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi - the diseases can be spread, directly or indirectly, from one person to another.
Antibiotic resistance - when bacteria change or evolve to no longer be killed by antibiotics.

What lessons are in this module?

Pathogens and Disease
The Body’s Defense
Pathogen Evolution and Antibiotic Resistance
The Epidemiology Triangle
Disease Transmission

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