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What is Epidemiology

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Definition of Epidemiology?   Purpose of Epidemiology Functions of Epidemiology Limitations of Epidemiology Basic Epidemiology Information Glossary of Epidemiologic Terms   Epidemiology Unit Logo Definition of Epidemiology Epidemiology is considered to be the basic science of public health. It is the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control health problems. Source: Last JM: A Dictionary of Epidemiology, Ed 2. New York, Oxford University Press, 1988. Health is defined by the World Health Organization (WHO) as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. __ Purpose of Epidemiology The fundamental purpose of epidemiology is to use data to evaluate the health of a population. Epidemiology is used to describe the causes of both health and disease and ways to minimize poor health in a population. The major objectives of epidemiology are:   - to identify the cause, the risk factors for a disease, condition, or health state; - to determine the extent of disease found in the community; - to study the natural history and prognosis of disease; - to evaluate both preventive measures and therapies; -to provide the foundations for developing public policy. It is important to use reliable, quality data to answer these questions in a systematic and scientific manner. __ Functions of Epidemiology A key function of epidemiology is to collect data through surveillance and reporting systems. This data is then analyzed to examine patterns and trends. Epidemiology looks at more than just demographic data or general frequencies of disease occurrence. Epidemiological studies and analysis often look for associations between outcomes and specific risk factors in addition to how diseases spread in a community over time. This analysis is interpreted, and reports and summaries communicate findings. While early epidemiological studies focused on infectious and communicable diseases, modern epidemiology is used to study chronic diseases, environmental exposures, and behavioral risk factors. Epidemiology uses data from hospital discharges, disease surveillance databases, cancer registries, and surveys. Surveillance systems include data about mortality, birth, and reportable diseases. (For a list of diseases that must be reported in San Mateo County, click here). __ Limitations of Epidemiology While epidemiology is a powerful tool for outbreak investigations and informing policy decisions, there are limitations. These limitations are those that affect all observational research. Several methodological problems may affect epidemiological findings. It is often difficult to say that a risk factor and disease that are associated are actually causally related. If a sample is too small, the precision of estimates may be affected. Other times, the association of a risk factor with a disease may show only a small effect. Another limitation is that when a study examines many potential risk factors, a few risk factors may be statistically significant by chance alone. Epidemiologic findings must be carefully interpreted. Chronic diseases and conditions with multiple risk factors are particularly challenging to assess. The complexity of chronic diseases makes exposure and risk factor information difficult to quantify and causal relationships may be difficult to clarify. __ Basic Epidemiology Information For more information about Epidemiology, visit the Foundation for American Communications website. The page is tailored for journalists but provides information about epidemiology for people of all professional backgrounds. __ Glossary of Epidemiologic Terms Click here for a link to a glossary of epidemiological terms. __ Meaning of the Water Pump Logo The water pump is the logo for the San Mateo County Epidemiology Unit and a general symbol of epidemiology. John Snow is considered the Father of Epidemiology. He was a physician in London during the mid 1800's who believed that cholera was spread primarily through contaminated water. Most others in the 1830s and 1840s believed that cholera was transmitted by inhaling vapors. In 1854, nearly 500 people who lived near the intersection of Cambridge and Broad Streets had died of cholera. Through interviews and mapping of individuals, Snow traced their cholera infection back to the Broad Street water pump. Officials removed the handle from the pump, and the outbreak was subsequently contained. Learn more about John Snow, the Father of Epidemiology here. __