Final answer:
Cardiovascular diseases are the leading cause of death in developed countries and are on the rise in developing nations, surpassing infectious diseases due to lifestyle factors that can be modified for prevention.
Step-by-step explanation:
The largest proportion of mortality in most developed countries and an increasing number of developing countries is caused by cardiovascular diseases. These include conditions such as heart disease, stroke, and diabetes, which are often linked to lifestyle choices and are largely preventable. Infectious diseases remain a significant cause of death in low-income countries; however, the burden of noninfectious diseases such as cancer and cardiovascular diseases is rising globally, driven by factors such as aging populations, urbanization, and the adoption of unhealthy lifestyles.
It is important to note that in higher-income nations, noncommunicable diseases like cardiovascular diseases and cancer are the leading causes of death. Factors contributing to these diseases include genetics, environmental influences, and lifestyle choices, with obesity, diabetes, and hypertension being key risk factors. Public health strategies aimed at prevention through modifying risk factors have proven effective in reducing the incidence of these diseases.