What is Epidemiology?
The textbook definition of epidemiology is: "The study of the distribution and determinants of diseases in human populations". Less formally, epidemiology is the scientific method used to track population health and to find causes of disease (and health) in groups of people. It is often called the basic science of public health, but its principles extend to clinical research.
Epidemiologists study causes and patterns of:
- chronic diseases (e.g., heart disease, cancer and diabetes)
- infectious diseases (e.g., flu and HIV)
- illnesses that result from environmental exposures to such agents as chemicals or pollutants
- illnesses that are related to genetic traits (e.g., cystic fibrosis, certain cancers)
- injuries (e.g., workplace injuries, injuries from violence and car accidents)
- mental illnesses (e.g., depression and schizophrenia)
- the risks and benefits of drugs
What Do Epidemiologists Do?
Epidemiologists improve the public’s health by studying causes of and solutions for population-wide health problems. The responsibilities of an epidemiologist may range from finding factors that affect a community’s health to carrying out sophisticated, scientific research using the most advanced techniques of modern molecular biology and genetics. On a typical day, an epidemiologist might spend time:
- designing a health study
- collecting or analyzing data
- writing reports
- speaking to the public and colleagues about research findings
Epidemiologists work in many different settings, including:
- state or local health departments
- government agencies such as: the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), or the National Institutes of Health (NIH)
- universities and academic institutions, such as schools of public health and schools of medicine
- private companies such as pharmaceutical corporations
- consulting firms
- international agencies like the World Health Organization
What Is an Epidemic?
Epidemiologists define an epidemic as any unusual occurrence of disease, generally first noticed by an unexpected number of cases occurring over a particular amount of time or in a particular place. During the course of an epidemic, epidemiologists work to identify the disease and its causes. For example, the surprising number of cases of a deadly form of pneumonia in China led to the identification of SARS and the virus that causes SARS.
We usually think about epidemics as acute events that take place rapidly and cause a dramatic increase in the numbers of deaths. Epidemics, however, can also be slow, or chronic—but equally deadly. Over the last 100 years, for example, there has been an ever-accelerating epidemic of lung cancer caused by cigarette smoking. Lung cancer had been rare at the start of last century, but at the century’s end, high rates of smoking had made the disease a common killer. Epidemiologists use the same methods to study both acute epidemics and chronic epidemics.
What Is a Pandemic?
A pandemic is an epidemic occurring over a very wide area, crossing international boundaries and usually affecting a large number of people. It is the term for a global epidemic. Due to its impact around the world, HIV/AIDS is considered a pandemic. The 1918 influenza is another example of a pandemic. Pandemics do not have to be caused by infectious diseases. The spread of health behaviors can create pandemics as well. For example, the increase in cigarette smoking around the world has led to a pandemic of lung cancer.
Epidemiologists are concerned about pandemics because the increased amount of travel in recent years and the speed at which people can travel from country to country would almost certainly help disease to spread faster than in the past.
(referenced from the Johns Hopkins Bloomberg School of Public Health)