ዶክፋን ፋርማ አካዳሚ

1. Ancient and medieval public health

People organised to protect health long before germs were known. Early cities in Mesopotamia and the Indus Valley built drains and bathing places. Roman engineers brought clean water through aqueducts and carried waste away in sewers. The Greek writings attributed to Hippocrates (about 400 BCE), such as Airs, Waters, Places, linked disease to climate, water, soil and the way people live. This is an early form of environmental and social thinking about health.

In the medieval period, epidemics of leprosy and plague led to the first systematic disease control. During the Black Death (1347 to 1351) port cities such as Venice and Dubrovnik (Ragusa) held arriving ships offshore. The period was first 30 days and later 40 days, the origin of the word quarantine (from quaranta giorni, forty days). Cities also appointed health boards, burned or buried the dead outside the walls, and registered deaths. Hospitals and medical schools in the Islamic world, and the writings of Ibn Sina (Avicenna), carried medical knowledge forward in the same centuries.

2. Renaissance, Enlightenment and the birth of numbers

• Fracastoro (1546) proposed that diseases spread by invisible “seeds” of contagion.
• John Graunt (1662) analysed London’s Bills of Mortality and showed that births, deaths and causes follow patterns. This is the start of vital statistics.
• Bernardino Ramazzini (1700) described diseases of workers and taught doctors to ask “What is your occupation?”
• James Lind (1747) ran a comparison of treatments for scurvy among sailors, an early controlled trial.
• Edward Jenner (1796) showed that cowpox material protected against smallpox. The word vaccine comes from vacca, Latin for cow.

3. Social reform and the sanitary movement (19th century)

Industrial cities grew fast, and crowded housing, dirty water and poor food produced cholera, typhoid and tuberculosis. Edwin Chadwick’s 1842 report on the sanitary condition of the labouring population argued that poverty and filth caused disease and that government must supply clean water and sewers. Britain’s Public Health Act (1848) created a central Board of Health. In the United States, Lemuel Shattuck’s 1850 Massachusetts report recommended state and local health boards. In Germany, Rudolf Virchow studied a typhus epidemic in Silesia (1848) and concluded that social and political conditions were the root causes. He is often quoted: “Medicine is a social science, and politics is nothing but medicine on a grand scale.”

John Snow and cholera. In 1854 a cholera outbreak struck the Soho district of London. Snow mapped the deaths and saw that they clustered around the water pump on Broad Street. He interviewed families, compared with people who used other water, and persuaded officials to remove the pump handle. The outbreak was already declining, but Snow’s method (map cases, compare exposed and unexposed, act on the pattern) is a model for outbreak investigation today. He did this before the cholera bacterium was discovered.

4. Germ versus miasma: the bacteriological revolution

Until the late 1800s most doctors believed in miasma, the idea that “bad air” from rotting matter caused disease. Reformers such as Chadwick acted on this idea, and cleaning cities did reduce disease even though the theory was wrong. The germ theory then gave a precise explanation.

Germ theory led to the discovery of the causes of many diseases within 30 years, then to antitoxins, vaccines, water filtration and chlorination, and later antibiotics.

5. Models of disease causation

In 1965 Austin Bradford Hill listed considerations that help judge whether an association is causal: strength, consistency, specificity, temporality (cause before effect), biological gradient, plausibility, coherence, experiment and analogy. Temporality is the only one that is essential.

6. The philosophy of public health

The World Health Organization’s Constitution (1948) describes health as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity”. C.-E. A. Winslow (1920) described public health as the science and art of preventing disease, prolonging life and promoting health through the organised efforts of society. The United States Institute of Medicine (1988) said public health is what we, as a society, do collectively to assure the conditions in which people can be healthy.

From these definitions come the core beliefs of the field:

• Population focus. The unit of concern is a group of people, not only the individual patient. Geoffrey Rose (1985) showed that small shifts across the whole population can prevent more cases than treating only the high-risk few.
• Prevention first. Stopping illness is better and often cheaper than treating it.
• Social justice and equity. Health differences that are avoidable and unfair are a matter of justice, and health is a human right.
• Collective responsibility. Some health protection can only be provided together (clean water, vaccination coverage, clean air), so government and communities have duties.
• Evidence and accountability. Actions should be based on data and judged by results.

7. Milestones and achievements

The US Centers for Disease Control and Prevention listed ten great public health achievements of the 20th century (1999): vaccination; motor-vehicle safety; safer workplaces; control of infectious diseases; decline in deaths from coronary heart disease and stroke; safer and healthier foods; healthier mothers and babies; family planning; fluoridation of drinking water; and recognition of tobacco use as a health hazard. Globally, life expectancy rose by more than 20 years in the century, smallpox was eradicated, and oral rehydration therapy saved millions of children. Ethiopia was among the last countries with endemic smallpox, with its final cases in 1976.

8. The era of new public health

From the 1970s the field widened. The Lalonde report (1974), the Alma-Ata Declaration (1978) and the Ottawa Charter (1986) moved attention from germs and hospitals to health promotion, primary health care, healthy public policy, community action and the social determinants of health. “New public health” combines the old agenda (infection and sanitation) with the new (chronic disease, mental health, injuries, environment, equity).