ECOLOGICAL TRIADA: Definition, Elements and Examples

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The health of people is directly related to the different types of diseases and pathogens that exist, so that advances in medicine always go hand in hand with scientific knowledge of these pathogens. In this field of scientific research, the ecological triad and the epidemiological chain play a really important role, since they make possible the study of the different interactions that occur in the development of diseases and their consequent spread, which sometimes causes pandemics, as in the case of the current coronavirus (COVID-19 or 2022-nCoV).

If you want to know more about the elements that intervene in the development and spread of diseases, continue reading this article by Ecologist Verde in which you will find all the information you need to know what the disease consists of. ecological triad: definition, elements and examples.

What is the ecological triad: simple definition

The ecological triad concept refers to the interactions that exist between different elements involved when a disease occurs, mainly but not always, of an infectious nature. It is called a triad because there are three elements that intervene during the disease process, and ecological, because these three elements or factors share an ecological character. It is a model that allows a better understanding of the elements and processes that characterize diseases, as well as the possibility of identifying patterns of action to combat these diseases.

In the next sections of the article we will see in detail what are the three elements that make up the ecological triad, as well as some examples of diseases and their associated ecological triads.

Elements of the ecological triad or epidemiological triad

As we have seen in the previous section, the elements that make up the ecological or epidemiological triad they are three. These are usually represented in the shape of a triangle, or as a balance, specifying the relationships that exist between them and the factors that constitute each element of the triad, these being:

• Epidemiological agent.
• Epidemiological host.
• Epidemiological environment.

Let's see in the next section what each of the three elements of the ecological triad consist of.

Epidemiological agent, the first element of the ecological triad

Are considered epidemiological agents each and every one of the different organisms that are capable of developing diseases in other organisms that act as hosts of the disease. The great variety of epidemiological agents that exist are included within bacteria, viruses or other groups of microscopic parasites, as is the case of some protozoa.

These epidemiological agents share a series of characteristics that make them organisms capable of causing disease. Between the characteristics of epidemiological agents stand out:

• Pathogenicity.
• Infectivity.
• Virulence.
• Antigenic power or immunogenicity.
• Lethality.
• Mutation.

At this point, we recommend that you also read this other article on Parasitism: definition and examples.

Epidemiological host

The second element of the ecological triad is the epidemiological host or susceptible host to contract the disease caused by the infection of the epidemiological agent.

Both human beings and animals and other living organisms can be considered as epidemiological hosts, whose resistance and / or immunity mechanisms at the time of infection are deficient and favor their susceptibility to contracting a disease. Said susceptibility may depend on different intrinsic characteristics of the hosts, such as age, heredity, environmental conditions, nutrition, and hormonal imbalance.

As for the routes of transmission of the disease, that is, the way in which the agent infects the host, they are usually the respiratory, digestive, urinary, and even through the skin and mucous membranes.

Environment, the third element of the edpidemiological triad

The environment plays a very important role in the process of infection and spread of diseases, since, according to the environmental conditions, infectious agents are able or not to reach the hosts.

In this way, in the environment as an element of the epidemiological triad Both physical factors specific to the environment (soil, water, wind, objects), as well as biotic factors (animals, food, or even human beings) are included; which act as vectors for the transmission of the disease.

On many occasions, a single change in the environmental and / or geographical conditions included within the environment are capable of allowing or preventing the spread of infectious diseases.

What is the epidemiological chain

Now that we know the three elements of the ecological triad, it is necessary to highlight the pattern or route that infectious agents follow from the source of infection to the hosts. Said model of interrelations is called epidemiological chain, which allows knowing each and every one of the different links and elements that intervene (directly or indirectly) in the development of a disease and its consequent transmission mechanism.

The epidemiological chain fulfills a really important function, since thanks to it it is possible to identify which element of the triad must be acted upon (through prevention and / or control measures), to deal with diseases. Thus, the six fundamental links in the epidemiological chain are:

1. Infectious agent.
2. Reservoir
3. Exit port of the infectious agent from the reservoir.
4. Transmission route.
5. Gateway from the agent to the guest.
6. Guest.

Ecological triad: examples

To better understand what the ecological triad is, let's look at the example of some of the most known diseases and their associated ecological triad:

Example of dengue ecological triad

• Agent: dengue virus.
• Environment vector: mosquito Aedes aegypti.
• Host: human.

Example of ecological triad of diabetes

• Agent: sugar.
• Environment vector: sugary drinks.
• Host: human.

Example of ecological triad of influenza

• Agent: influenza virus.
• Environment vector: animal.
• Host: human.

We recommend that you learn more about this topic with these other Green Ecologist articles on Are viruses living beings? and about the Difference between viruses and bacteria.

If you want to read more articles similar to Ecological triad: definition, elements and examples, we recommend that you enter our Health and Science category.

Bibliography

• M. R. Ochoa, et al., (2015) Analysis of dengue, its transmitting agent and prevention and control strategies. Camagüey Medical Archive Magazine. Volume 19 (2).
• Rosenberg F.J. & Mello, P.A. (2004) FMD virus carriers, terminal process of infection or intermediate link in the epidemiological chain of the disease? World Health Organization Newsletter. Volume 13 (16), pp: 50-60.