Question

Use an infectious disease as an example, identify how an epidemiologist may use the Epidemiologic Triangle to prevent and/or control the disease.

Answer 1

The germ theory of disease has many limitations. For example, it is well known ,that everyone exposed to tuberculosis develops tuberculosis.The same exposure , however in an undernourished or otherwise susceptible person may result in clinical disease. Similarly, not everyone exposed to beta- haemolytic streptococci develops acute rheumatic fever. There are other factors relating to the host and environment which play important roles in determining whether or not disease will occur in the exposed host. The factors of causation of disease may be classified as agent, host and environment . These three factors are referred as "EPIDEMIOLOGICAL TRIAD".

The first one in the chain of disease transmission is a disease agent. Agent is a substance which may be living or non living . Human immuno deficiency virus is a viral agent that targets a person’s immune system opens in new window, making it more vulnerable to other forms of infection. As the virus targets the immune system , the body ; immune system cannot effectively fight HIV on its own. HIV is contracted through direct contact with an infected person’s bodily fluids, and it primarily spreads through sexual contact or shared needles or blood transfusion.

The next is the host factors. The association of a particular disease with a specific set of host factors mostly provide a blue print of cause of disease.The host factors play an important role in determining the outcome of an individual's risk of exposure to any infection. Scientists has found that AIDS virus was originally carried by monkeys (chimpanzees) and that humans who hunted these for meat affected with a mutated form of the virus upon contact with the chimpanzees’ blood. HIV can be transmitted via bodily fluid and also when infected blood comes in contact with a open wound in mucous membrane or damaged tissue .

Study of disease involves two factors studying the person and his environment. There are numerous socio environmental factors contributing to infection of HIV. Communities with more sexually transmitted infections but not reported due to social pressure and shame is the place where HIV infection flourish. Poverty , unemployment and lack of education may also contribute to the disease progression.