Ecological triad or epidemiological triad

Today is our topic of discussion Ecological triad or epidemiological triad

Ecological triad or epidemiological triad

Ecology:

It is the study of mutual relationship between living organisms. wed

Ecological triad:

The causative factors for the occurrence of a disease are regarded as the interaction among the agent, host and environment. The theory that combines these three factors is referred to as the ‘epidemiological/ecological triad or triangle’. 

The mere presence of the factors in pre-pathogenesis period is not sufficient to start the disease. The important event essential for the occurrence of disease is the interaction among these three factors – a harmful agent comes into contact with a susceptible host in a proper environment.

Fig: ‘Ecological triad’ or ‘epidemiologic triangle’

Importance of ecological triad:

1. The cycle can be blocked by intersecting the triangle at any of its three sides of the triangle. 
2. It helps epidemiologists to focus on different classes of factors, especially with regard to infectious diseases. 

Concepts of ‘causation of disease’:

Regarding the causation of the disease, few theories have been evolved –

1. The germ theory: This theory implies that disease occurs due to bad air 
2. Epidemiological triad: The disease occur when agent, host and environmental factors are not in balance

         a) Due to new agent.

         b) Due to change in existing agent (infectivity, pathogenecity, virulence).

         c) Due to change in number of susceptible individual in the population. nm orb nitive to enc

         d) Due to environmental changes that affect transmission of the agent or growth of the Agent.

3. Multifactorial causation: Multiple risk factors are involved for the causation of disease. land olda
4. Web of causation: Includes the predisposing factors for causation of disease

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