Why might epidemiology be considered more essential for the study of non-infectious diseases than the study of infectious diseases? (A) The causes of infectious diseases have already been determined - HSC - SSCE Biology - Question 16 - 2015 - Paper 1

Epidemiology plays a crucial role in understanding patterns and determinants of health and diseases in populations. Non-infectious diseases, such as chronic conditions, often arise from lifestyle factors, genetic predisposition, and environmental influences. Unlike infectious diseases, which can often be traced to specific pathogens, non-infectious diseases require a broader approach to analyze complex interactions among various determinants.

Given the options:

• (A) The causes of infectious diseases have already been determined: This statement is misleading since many infectious diseases still have unknown causes or require ongoing research for new strains.
• (B) Only non-infectious diseases are affected by patterns of behaviour: This is not accurate, as infectious diseases are also influenced by behavior, but non-infectious diseases typically require behavioral analysis for prevention.
• (C) Epidemiology cannot be used to find the causes of infectious diseases: This is incorrect; epidemiology is vital in studying all disease types.
• (D) Koch’s postulates are not useful in finding the causes of non-infectious diseases: This accurately points to a limitation of Koch's postulates, which were originally designed for infectious diseases.

Thus, option (D) is correct. It emphasizes the challenges faced by epidemiologists when studying non-infectious diseases, where Koch’s postulates do not apply.