Passage 1

The Changing Landscape of Health and Disease

For centuries, human health has been defined primarily by the absence of sickness. Yet since the early twentieth century, the concept has broadened considerably. The World Health Organization (WHO) famously describes health as 'a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity'. This definition, though criticized for being idealistic, highlights a fundamental shift in thinking: health is no longer viewed as the simple opposite of illness, but as a positive asset shaped by a complex array of factors.

One important consequence of this broader perspective is attention to the so-called 'epidemiological transition'. During industrialization, improved sanitation, vaccination and antibiotics dramatically reduced death from infectious diseases in high-income countries. In their place, chronic or noncommunicable diseases (NCDs) became the leading causes of death. Today, NCDs are estimated to kill 41 million people each year, roughly 71 per cent of all global deaths. The four main categories are cardiovascular diseases, cancers, chronic respiratory diseases and diabetes. Although often associated with affluence, NCDs now disproportionately affect low- and middle-income countries, where people face a 'double burden' of coping with both lingering infections and rising chronic conditions.

Many NCDs share common behavioural risk factors. Tobacco use, harmful alcohol consumption, physical inactivity and unhealthy diets account for a large share of disease burden. For instance, physical inactivity alone is among the top ten causes of death worldwide. However, individual lifestyle choices are not made in a vacuum. A person's ability to eat well, exercise regularly and avoid tobacco is strongly influenced by social determinants such as income, education, employment, housing and access to healthy food. Poor environmental conditions, including air pollution, add another layer of risk. Thus, telling people to change their habits is rarely enough; supportive environments are essential.

Health is also a mental as well as physical matter. According to global estimates, one in four people will experience a mental or neurological disorder at some point in life. Depression is currently the leading cause of disability worldwide, yet it remains under-diagnosed and under-treated. Stigma around mental illness often prevents people from seeking help. The relationship between mental and physical health is bidirectional: persistent anxiety raises the risk of cardiovascular problems, while chronic illness can trigger depression. Mental health, therefore, should not be treated as a secondary concern but as an integral component of overall well-being.

The response to these challenges has increasingly focused on universal health coverage (UHC), the idea that all people should receive the health services they need without suffering financial hardship. UHC includes not only treatment but also prevention and health promotion. Strengthening primary health care is widely regarded as the most effective and equitable strategy, because primary care can manage common conditions close to home and coordinate more specialized services when needed. Yet health systems in many countries remain focused on hospitals and curative medicine rather than public health and prevention.

In recent decades, enormous progress has been made in increasing life expectancy and reducing child mortality. The global under-five mortality rate fell by more than half from 1990 to 2019. In addition, new vaccines have eradicated or controlled several ancient diseases. Nevertheless, progress is uneven, and new threats constantly appear. Antimicrobial resistance, the climate crisis and an increasingly globalized food system pose serious challenges to health security. The COVID-19 pandemic demonstrated how a new pathogen can disrupt every dimension of human life and widened existing inequalities.

In conclusion, the changing landscape of health demands a comprehensive approach. No single medicine can cure the consequences of poverty, pollution or stress. Governments, communities and individuals all have a role to play in creating conditions that allow people to lead healthy lives. Ultimately, health is not just a personal responsibility but a social achievement.