Field Epidemiology

The term field epidemiology describes the application of epidemiologic methods, usually by representatives of a public health service, to address specific healthrelated questions in community settings. Many, if not most, field investigations address urgent or acute health problems. However, many others are conducted as planned studies addressing less urgent needs. All field investigations have in common the aim of conducting scientifically rigorous studies, sometimes under difficult circumstances, to answer very specific epidemiologic questions with the ultimate aim of planning, implementing, or evaluating public health interventions.

Outbreak investigations are a prominent example of field epidemiology studies and serve to illustrate many of the characteristics common to all field investigations. An outbreak investigation, like other field investigations, has the following goals: (a) to determine the cause and etiology of the disease, (b) to limit the spread and severity of illness of the disease, and (c) to prevent future outbreaks. In addition, investigations of this sort can serve to identify new modes of transmission of illnesses, identify new pathogens, and monitor the effectiveness of prevention activities.

Field epidemiology also includes investigations conducted in several different types of community settings, each involving its own challenges. These settings may include health care facilities, child care settings, occupational settings, and even areas affected by natural disasters.

Investigations in health care settings, such as hospitals, rehabilitation centers, transitional care centers, outpatient settings, and long-term care facilities, differ from other field investigations in several ways. First of all, most of the infections encountered are endemic to the setting and are unlikely to be completely eradicated. Patients affected in these settings typically have additional medical conditions that render them more susceptible to adverse sequelae than healthier community-based individuals. The infectious agents involved in health-care-related outbreaks are a greater danger to the patients and health care workers in the [Page 389]facility than to the general public outside the facility. Finally, an outbreak in a health care facility may require even more rapid identification and control than a community-based problem, not only because the risk of litigation is higher but also because of the greater vulnerability of the patients to the infection. These distinctions aside, the methods used to identify and control an outbreak in a health care setting are basically the same as for a community-based outbreak.

Child care settings present issues similar to those in other care facilities, though the ‘at-risk’ population is not confined to the facility itself. Epidemiologists need to be aware of the potential spread of illness beyond the children and child care providers to family contacts and children encountered in other settings such as schools, community playgrounds, and the like.

Field epidemiology may also be conducted in areas affected by disasters, either natural or man-made. Such investigations typically involve, at least initially, the gathering and summarizing of data about the needs of the affected population: What food is available or needed? Are water sources available? What medical conditions and/or injuries are prominent or likely to occur, and what medications, treatments, and medical personnel are needed? Early data such as these can be used to guide humanitarian and relief efforts, matching available resources to the needs. In addition to assessing the needs of the populations, epidemiologists may be called on to assist in preventing further adverse health effects, to evaluate the effectiveness of relief programs in meeting the most immediate needs of the population, and to assist in contingency planning. Epidemiologists may also need to quickly establish surveillance systems, monitoring ongoing health risks and adverse events, evaluating the effectiveness of clinical interventions, and identifying potential risk factors for developing adverse outcomes. Opportunities exist as well for studying the natural history of a disaster and its potential for longterm health impacts. In the setting of a natural disaster, field epidemiologists may serve as a communication and coordination hub for medical personnel, relief effort coordinators, and other decision makers, making skills in communication, coordination, and public relations key.

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