Natural and Human-Made Disasters

Epidemiologic evidence is a critical element of humanitarian assistance. The identification of appropriate interventions for priority health problems depends heavily on the rapid collection, analysis, and interpretation of data derived from sound methods adapted to challenging circumstances. In the relative chaos of the emergency setting, accurate determination of both numerators and denominators can depend on the ability to be observant, innovative, and flexible. In addition to possessing technical skills, the humanitarian epidemiologist needs to be a strong advocate for the importance of data, an excellent communicator, and a team player. At all times, the epidemiologist should remember that every action taken is not about producing more and better data, but rather about saving imperiled lives.

Exposures and Conditions of Acute Environmental Origin

Investigations of acute events with suspected environmental associations include unique decision points and action steps. Public health professionals should prepare to respond to these investigations by maintaining expertise in fields including toxicology, environmental epidemiology, environmental and occupational medicine, industrial hygiene, environmental risk assessment, and environmental monitoring. Notification of a disease cluster or of an acute exposure event is often the initial trigger for public health awareness of the situation. Setting case definitions and characterizing exposure can be challenging, and input might be needed from subject matter experts, responders, and partners outside of public health. Quantifying the magnitude and route of exposure, understanding the inherent toxicity and duration of exposure, and other factors are unique steps in environmental investigations. Effective risk communication to affected communities and involved partners is critical and should be carefully planned.

Healthcare Settings

Healthcare-associated infections (e.g., bloodstream, respiratory tract, urinary tract, or surgical site) can be common in patients. Patients receiving acute and chronic healthcare across various settings, such as hospitals, dialysis clinics, and nursing homes, tend to have comorbidities that make them more susceptible to infection than their counterparts in the general community. Also, some pathogens may be more likely to cause infection in healthcare settings because of the unique exposures that patients can experience, such as invasive procedures or indwelling medical devices. Similar to community outbreak investigations, the primary purpose of an investigation in a healthcare setting is to determine the source of the outbreak, define mode of transmission, disrupt disease transmission, and prevent further transmission.

Multinational Outbreak Investigations

Multinational collaborations on international outbreak investigations and response have a long history. Development of the World Health Organization (WHO) in 1948 was closely linked to efforts by the global community to prevent, detect, and respond to outbreaks of international concern. Through the International Health Regulations (IHR) of 2005, a legally binding instrument requiring countries to report certain outbreaks and public health events, WHO outlined a strategy for disease threat response. Efforts by global partners to strengthen cooperation have evolved over the years, including roles and responsibilities of WHO, its Member States, and other partners. Among the challenges faced by Member State and WHO in implementing the IHRs are limited funding to support staffing and operational support as well as sometimes conflicting multijurisdictional decision-making. The response to recent outbreaks provides evidence that much work remains to be done to strengthen IHR mechanisms.

Communicating During an Outbreak or Public Health Investigation

Effective communication during an outbreak or public health investigation is crucial for fostering adoption of public health recommendations and minimizing or preventing harm. During outbreaks, a comprehensive communication strategy integrating news media, social media, and partner engagement is essential for reaching affected persons and for keeping everyone informed about public health actions and recommendations. The strategies outlined in this chapter are the foundation for rapidly and effectively conveying information and public health recommendations to the persons at risk, the media, and the different entities involved in the response. Regardless of the public health event’s cause, core communication actions and steps will be similar; however, in every outbreak or public health investigation, perceptions and needs will vary among target audiences, partners (i.e., persons or organizations that can play a role in the crisis response), and persons or organizations with a connection or interest in the outbreak (stakeholders).

Collecting and Analyzing Qualitative Data

Qualitative research provides an adaptable, open-ended, rigorous method to explore local perceptions of an issue. Qualitative approaches are effective at revealing the subjective logic motivating behavior. They are particularly appropriate for research questions that are exploratory in nature or involve issues of meaning rather than magnitude or frequency. Key advantages of qualitative approaches include speed, flexibility and high internal validity resulting from emphasis on rapport building and ability to probe beneath the surface of initial responses. Given the time-intensive nature of qualitative analysis, samples tend to be small and purposively selected to assure every interview counts. Qualitative studies can be done independently or embedded in mixed-method designs. Qualitative data analysis depends on rigorous reading and rereading texts ideally with more than one analyst to confirm interpretations. Computer software is useful for analyzing large data sets but manual coding is often sufficient for rapid assessments in field settings..

Describing Epidemiologic Data

Descriptive epidemiology is a systematic organization of reliable data to sharpen understanding of health problems. It addresses the five questions of what (the health condition), how much (counts, rates, and averages), when (time), where (place), and among whom (person). The field epidemiologist organizes these data into tables, graphs, maps, charts, and other displays to reveal patterns of a health problem by these five questions.

Conducting a Field Investigation

Performing field investigations is a core function of epidemiology in public health. When a threat to the public’s health occurs, epidemiologists investigate to describe the problem and identify causes, recommend immediate prevention and control measures, and provide a foundation for communicating information quickly to those who need to know to save lives and protect people from future illness. Although diseases and evaluative technologies evolve continually, the approach to conducting an epidemiologic field investigation remains relatively constant. Investigating an outbreak requires both a speedy and accurate response, necessitating a systematic approach that results in action. This chapter describes the basic 10-step approach for conducting an epidemiologic field investigation. Although the steps in this chapter are presented in a numeric and conceptual order, the order sometimes changes in practice. Ultimately, the goal of any epidemiologic field investigation is to use the science of epidemiology to rapidly ensure public health and safety.

Acute Enteric Disease Outbreaks

Public health officials investigate outbreaks to control them, to prevent additional illnesses, and to learn how to prevent similar outbreaks in the future. The process the public health community uses to detect, investigate, and control enteric (intestinal) disease outbreaks from food, water, and other sources involves certain procedural steps. These include detecting a possible outbreak, defining and finding cases, generating hypotheses about likely sources, testing the hypotheses and evaluating evidence, finding contamination sources, controlling the outbreak, and determining when the outbreak is over. Investigating outbreaks of acute enteric diseases can be a dynamic and complex undertaking involving multiple public health and regulatory partners in different jurisdictions. This chapter provides an overview of the investigation process with an emphasis on multijurisdictional foodborne illness investigations in the United States.

Coordination of Multiple States and Federal Agencies

Although most outbreaks are confined to a local jurisdiction, the number of multijurisdictional outbreaks (i.e., involving multiple geographic areas, widely distributed contaminated food or pharmaceutical products, or multiple government agencies) is increasing. In such cases, a clear and effective management system for the response must be established promptly. The roles and expectations of all involved responders should be clearly defined and closely monitored. Partners should be in regular communication throughout the response. Procedures and mechanisms for sharing of appropriate data and protecting sensitive information should be established from the onset of the investigation. Public communication about the investigation and response should be closely coordinated among agencies and preferably handled by a single spokesperson. Following the established procedures of the Incident Command System is often appropriate for large-scale or multijurisdictional outbreak responses.