The Public Health Revolution
Pandemics led to the public health revolution in developed countries in
the aftermath of the Industrial Revolution, massive migration from rural
areas to cities, and the emergence of overcrowded and filthy slums
inhabited by the working classes. A comprehensive definition of ‘public
health’ is:
Public health is the science and art of preventing disease, prolonging
life, and promoting physical health and efficiency through organized
community efforts for the sanitation of the environment, the control of
community infections, the education of the individual in the principles
of personal hygiene, the organization of medical and nursing services
for the early diagnosis and preventive treatment of disease, and the
development of social machinery which will ensure to every individual in
the community a standard of living adequate for the maintenance of
health.
The goal of public health is to create a conducive environment to
promote the health of the community and prevent diseases. It adopts two
broad approaches: population-based and clinical. The population-based
approach delves into the social and environmental determinants of
health: congested housing, poor sanitation, lack of sewers, polluted
air, etc. Clinical methods focus on screening, counseling, and treatment
of diseases in clinical settings. As many socio-environmental and
biological factors influence health outcomes, the practice of public
health does not rely on any specific body of knowledge. It rather
applies a mix of science and social management approaches, depending on
the context.
The growth of scientific knowledge about diseases, the development of
means to prevent and control them, social reforms promoting the value of
hygiene and health, and the organization of public institutions,
including the empowerment of municipalities to implement interventions,
were the pillars of the public health movement in developed countries.
These countries made enormous investments in public health, related
infrastructure, and spatial planning to maximize the benefits of urban
development while minimizing its negative consequences, such as
congestion, disease, etc. For example, the cholera eruption in
nineteenth-century London led to huge national investments in water
supply, sewerage, drainage, and sanitation in the city. The tuberculosis
outbreak in the twentieth century in New York City resulted in
improvements in tenement regulations, housing reforms, and public
transit. The SARS pandemic in the twenty-first century in Asia led to
significant upgrading of medical infrastructure and scientific mapping
of the spread of disease to enable focused interventions by public
health authorities.
Advances in public health have significantly impacted nations through a
reduction in mortality, an increase in longevity, and a rise in labor
productivity. Life expectancy at birth in industrialized countries rose
from 45 years to 75 years during the twentieth century. The majority of
the gain – 25 out of 30 years – is attributed to public health
improvements, including better nutrition, sanitation, safer housing, and
other non-medical factors. The largest gains in life expectancy in the
United States occurred between 1880 and 1920 due to infectious disease
control, clean water, and sanitation. to three phases of ‘mortality
transition.’ In the first phase – from the middle of the eighteenth to
the middle of the nineteenth century, improvements in nutrition,
economic growth, and incipient public health measures might have played
a key role. In the second phase – from the last decades of the
nineteenth century to the first decades of the twentieth, public health
developments overwhelmingly dominated the factors contributing to
mortality reduction. These include improvements in water supply and
sanitation, food safety, vaccination, and efforts to improve personal
hygiene. The third phase – from the 1930s – is the era of big
medicine, marked by antibiotics, new vaccines following advances in
bacteriology, and intensive personal interventions that characterize the
modern medical system.