Assignment:

Describe this traditional triangle of epidemiology. What model is this triangle based on? What are the different components of the triangle? Provide examples relevant to this triangle.

The four epidemiologic factors contributed to an outbreak in the 1500s whipping out entire populations. These factors are: 1. The role of the host, 2. The agent or disease-causing organism, 3. The environmental circumstances needed for the disease or pathogen to survive and spread, 4. Time related issues. Such an epidemic ran wild because of poor sanitation and basic knowledge of the disease, they had low levels of immunity, there were various modes of transmission and the environmental factors were an issue as well. The traditional triangle is used to express the connection between the host, the agent and the environment. “This triangle is based on the communicable disease model and is useful in showing the interaction and interdependence of the agent, host, environment, and time as used in the investigation of diseases and epidemics”(Merrill, 2013). The agent is the cause of the disease (bacteria, virus, fungi, parasites, etc). The host is an organism like a human or animal that holds the disease. The environment consists of the surrounding outside the host that cause or allow transmission of pathogens; examples include physical stress (excessive heat, cold, noise, radiation, etc), chemicals (drugs, acids, heavy metals, poisons, etc) and psychosocial milieu (families, socioeconomic status, social networks, etc). Time explains the incubation period, the life expectancy of the host and/or pathogen and the length of the illness or condition given from the pathogen. “Delays in time from infection to when symptoms develop, duration of illness, and the threshold of an epidemic in a population are time elements with which the epidemiologist is concerned” (Merrill, 2013).

An example of this triangle is Tuberculosis.

Agent: Tuberculosis

Host: Human

Environment: airborne bacteria that can be spread from person to person through microscopic droplets that is released in the air. Ex: cough, breathing, spits, laughs, sneezes.

Time: Latent period is an inactive period where the infection remains inside of the host but shows no symptoms and an active period can develop within the first two years of the infection.

Merrill, R., (2013). Introduction to Epidemiology. (6th Edition). Burlington, MA: Jones and Bartlett Learning, LLC.