Preventive Medicine

The medical discipline of preventive medicine covers the gamut of measures, individual and societal, that can reduce the occurrence of illness and injury. Physicians who practice in preventive medicine may be infectious disease specialists, community health specialists, and occupational health specialists. Preventive medicine is also a mainstay of most other medical specialties, notably family practice, internal medicine, and pediatrics. The research field of epidemiology studies trends in and risks for illness and injury and explores methods for reducing health risks. Epidemiologists and preventive medicine practitioners work closely together.

This section, “Preventive Medicine,” presents an overview discussion of preventive medicine concepts and entries about preventive health measures and the public health dimensions of illness and injury. The entries in this section focus on the larger picture of how illness and injury affect the health and well-being of communities and populations. Entries in other sections of The Facts On File Encyclopedia of Health and Medicine provide detailed content about the causes, symptoms, diagnosis, treatment, and outlook for specific infections and diseases. Cross-references link the entries to one another.

Traditions in Preventive Medicine History

Early cultures and medical systems had their unique variations on preventing illness and INFECTION. There is some evidence of guidelines for sanitation and public health practices in ancient Macedonia, and the ruins of ancient Rome’s intricate aqueducts and sewage canals remain today. But for the most part the premise of public health is relatively modern, emerging after a flurry of scientific discoveries in the 19th century that revealed the pathogenesis (origin and progression) of infection and disease. Key to these discoveries were the observations of physicians such as Ignaz Philipp Semmelweis, who was the first to make the connection that doctors carried the infection of childbirth FEVER from one patient to another through blood on their hands and clothing, and the experiments of scientists such as Joseph Lister, Louis Pasteur, and Robert Koch, whose discoveries proved the existence of microbes and the value of antisepsis in preventing the spread of infection. Their work further led to the development of antibiotics and vaccines.

These three factors-antisepsis, antibiotics, and vaccines-forever changed the perceptions and patterns of disease throughout the world and are among the most significant breakthroughs in medical history. In less than half a century these discoveries dramatically reduced the occurrence and severity of many diseases that had for millennia been the leading causes of death: tetanus, ANTHRAX, SMALLPOX, CHOLERA, TYPHOID FEVER, DIPHTHERIA, PERTUSSIS, POLIOMYELITIS, SYPHILIS, bacterial PNEUMONIA, bacterial wound infections, INFLUENZA, and TUBERCULOSIS. Though death due to infection after CHILDBIRTH is rare in the United States today, until the early 20th century childbirth fever (puerperal fever) was a leading cause of death among women of childbearing age. From 1900 to 1999, maternal death in childbirth declined 99 percent in the United States.


  • eradication of SMALLPOX in the United States in 1967 and worldwide in 1977
  • near eradication of MEASLES in the United States in 1998
  • near eradication of POLIOMYELITIS in the United States in 2000

Public Health

Improvements in COMMUNITY SANITATION, such as sewage and garbage control, in the late 19th and early 20th centuries further contained diseases spread through close contact reduced pest and vermin infestation and the resultant diseases, including the much dreaded “black death,” plague. Cities and towns focused effort on maintaining clean and safe drinking water supplies, decreasing waterborne illnesses. The home refrigerator debuted in 1913 and quickly replaced the icebox as the standard for food storage, dramatically decreasing FOODBORNE ILLNESSES.

Doctors and others began to recognize, by the start of the 20th century, the extent to which community and personal cleanliness influenced health and illness. Poor ventilation and overcrowded living and working conditions, especially in densely populated cities, encouraged rampant and rapid spread of infectious diseases. In 1900 pneumonia, tuberculosis, and GASTROENTERITIS together were to blame for a third of all deaths in the United States. Annual influenza outbreaks could kill entire families, even communities, within weeks. In cities, infections caused the deaths of nearly a third of infants before their first birthdays.

With clean water standards came assurances that bathing would no longer be the source of illness but rather could be the guardian of health. Public officials began to extol the virtues of frequent HAND WASHING and daily, or at least weekly, bathing. Between 1920 and 1937 illnesses and deaths from waterborne infections such as cholera and typhoid fever plummeted, and by 1950 were nearly nonexistent. Health officials also encouraged opening windows and getting fresh air, measures that helped dilute the concentration of airborne pathogens such as viruses and BACTERIA and reduce opportunities for infection to occur. In 1944 the US Congress passed the Public Health Service Act that established a consistent framework for public health laws, standards, and procedures throughout the United States.

Life expectancy

A key measure of public health and the effectiveness of disease-prevention efforts is LIFE EXPECTANCY. A child born in 1900 could expect to live to age 47. A child born in 1950, the dawn of the golden era of preventive health care, could expect to live nearly half again as long, to age 68. These children were the first who also could expect to grow up without experiencing the CHILDHOOD DISEASES that claimed the lives of one in five children in their parents’ generation.

Epidemics and pandemics

Epidemics and pandemics strike fear in the hearts of health experts and individuals alike. Epidemics are extensive but localized outbreaks of illness or infection. Pandemics are worldwide outbreaks. Despite vaccination efforts, annual influenza epidemics sicken millions and cause the deaths of 30,000 Americans. Health experts believe basic preventive measures such as frequent hand washing and appropriate SNEEZE/COUGH ETIQUETTE, combined with more comprehensive vaccination, could prevent most of these infections.

The Spanish influenza epidemic of 1918, the worst pandemic of modern history, claimed the lives of half a million Americans and more than 20 million people worldwide. It also provided much learning for public health officials about how, and how quickly, such infections spread. Health experts have used this knowledge to develop mechanisms and systems to detect and report outbreaks that have pandemic potential. Such efforts could not entirely prevent, though did help contain, influenza pandemics in 1957 (the Asian flu) and 1968 (the Hong Kong flu). They did, however, allow early detection and containment of small outbreaks of avian influenza in 2000 and 2004, and of the deadly SEVERE ACUTE RESPIRATORY SYNDROME (SARS).

Motor vehicle safety

A uniquely modern-day public health issue is motor vehicle safety. Coming into its own in the early 1900s, the automobile wasted little time acquiring notoriety. By the time Henry Ford set the standard for the “everyman” car, MOTOR VEHICLE ACCIDENTS had already claimed more than 40,000 lives. By the 1960s, motor vehicle accidents accounted for more than 40,000 deaths each year. Measures such as structural integrity requirements, seat belts, and airbags have held motor vehicle deaths steady near that level since 1998.