Tutor Marked Exercise



Tutor Marked Exercise

Tutor Marked Exercise 1

Explain the relative benefits of the following models to describe disease causation:

The epidemiological triangle

Epidemiology is the branch of medicine devoted to the study of the distribution, frequency, determinants, relationships, prediction and control of factors related to health and disease in certain human populations and the application of this study to the problems of health. Therefore health epidemiology studies of human groups in relation to their environment. Epidemiology is considered the basic science for preventive medicine and a source of information for formulating public health policies. The epidemiology studies, especially the cause-effect relationship between exposure and disease. Diseases do not occur randomly; have causes, many of them of human origin, which can be avoided. Thus, many diseases could be prevented if they had known their causes. Epidemiological methods have been crucial in identifying numerous etiologic factors, in turn, have justified the formulation of health policies aimed at preventing disease, injury and premature death.

The epidemiological triangle causal of disease consists of the environment, agents and the host. A change in any of these three components will alter the existing balance to increase or decrease the frequency of the disease; therefore can be called causal factors or determinants of disease. The basic premise for undertaking disease prevention can be understood by an awareness of the epidemiological triangle (see Figure 1). An agent may be thought of as a substance that must be present for a disease or condition to occur. Transmission of an agent to a host may be accomplished in a variety of ways: infectious agents such as bacteria, viruses and parasites by contact; chemical agents such as toxic chemicals or pesticides may be inhaled, or absorbed through the skin; poisons may be ingested.

Environmental factors include climate (temperature, rainfall); plant and animal life (agents, reservoirs or habitats for agents); human population distribution (crowding, social support, resources, and access to care); and working conditions (stress, noise, job satisfaction). Host factors concern the health status of the human and include genetic susceptibility; immutable and age/gender, characteristics; immunology status; lifestyle factors; diet and exercise. Prevention strategies are ones which seek to address these factors either individually or concurrently. Reducing or eliminating this probability is the goal of prevention. The power of the biomedical approach to disease prevention can be seen by examining the reduction in communicable disease; for example, smallpox was responsible for an estimated 300-500 million deaths in the twentieth century. Following improvement of the host's immune system via vaccination, smallpox was eradicated in 1979.

In critiquing disease prevention model, Baggott (2000) informs us that the biomedical approach generalises health behaviours to a focus on danger and risk. This leads to a requirement for greater surveillance and attempts to orientate health behaviours to health outcomes. This process however adopts a victim-blaming approach, where the individual concerned is blamed for health outcomes, due to their own risky behaviour. No consideration is given to the social, environmental and political factors that influence health choices.

The so-called epidemiological triad or triangle is ...