Initiating Operations

Duc J. Vugia, Richard A. Goodman, James L. Hadler, and Danice K. Eaton


In the United States, the responsibility for public health rests primarily with city or county and state public health agencies. All states and many large counties and cities have their own public health departments. Although many public health investigations are conducted with local resources, a city, county, or state health department can request field epidemiologic or laboratory assistance from the next higher level public health agency in response to a large or complex outbreak or problem that requires additional staff, expertise, or other resources. In the United States, the Centers for Disease Control and Prevention (CDC) is the highest level public health agency. Federal prisons, military bases, and tribal reservations have their own independent health systems but also can request assistance from CDC. Globally, countries can request assistance for field investigations from the World Health Organization, which coordinates with its members for needed resources.

An epidemiologic field investigation entails considerably more effort than simply following the recommended, scientifically oriented steps as enumerated and described in Chapter 3. Numerous operational concerns must be addressed in addition to the necessary data collection, tabulation, and analyses. This chapter describes crucial operational and management steps and principles that apply before, during, and after the field work, often to both invitees and inviters.


Initial Request, Communications, and Formal Invitation

Initial Request and Communications

When requesting epidemiologic assistance, inviters should gather as much information as possible about the outbreak or problem and communicate the details, along with a formal invitation, to the invited agency to prepare for initial teleconference meetings. At the initial teleconference meeting, invitees and inviters should attempt to answer the following questions:

  • What is the purpose of the investigation?
    • Is the local or state health department simply requesting additional staff to complete the investigation?
    • Has the local or state health department been unable to determine the source of disease or the mode of spread?
    • Does the local or state health department want to share the responsibility of the investigation with others to more fully address the political or scientific pressure?
  • What specifically is the investigation expected to accomplish? The field team might be asked to confirm findings from data already collected or perform an entirely new investigation and develop new recommendations.
  • What authority does the inviter have to request assistance? Occasionally, field investigations have been aborted simply because persons requesting assistance had no authority to do so.

Formal Invitation

An essential consideration is the need for a formal request for assistance from an official who is authorized to request help. In the United States, each state has a State Epidemiologist. This official usually has the authority and responsibility for major epidemiologic field investigations of acute public health problems and for deciding whether to investigate independently within the state or to request CDC assistance on behalf of the state or a local health department. However, a State Epidemiologist first needs to inform his or her State Health Officer and, depending on the sociopolitical context, obtain permission to proceed with a formal invitation. At the city or county health department level, a senior city or county public health officer usually has authority to invite assistance from the state health department. For international problems, determining who has authority to extend a request can be more complicated and might involve, for example, senior officials from ministries of health requesting assistance from the World Health Organization.

Clarification of Objectives, Roles, and Responsibilities

Depending on the extent and complexity of the outbreak or problem and the main purpose(s) of the field investigation initially discussed, subsequent communications between invitees and inviters should focus on clarifying the investigation’s main objectives and the roles and responsibilities of key persons.

  • What are the main public health questions the field investigation needs to answer? The primary purpose of field investigations in response to outbreaks or other urgent public health events is to identify control and prevention measures.
  • What is the status of the Incident Command System (ICS) and local Emergency Operations Center (EOC) (see also under Other Issues)? Have they already been activated or are likely to be activated? If so, what will be the role of the field team?
  • What epidemiology, laboratory, and other resources (including personnel) will the jurisdiction requesting assistance provide?
  • What resources will the visiting team and responding agency provide?
  • Who will supervise the day-to-day investigation?
  • Who will provide overall direction and ultimately be responsible for the investigation?
  • Who will be the media point person for the investigation?
  • Who will be responsible for data analyses, and how will data be shared?
  • Who will write a report of the findings, if needed? To whom will it be disseminated?
  • Who will be the lead and senior authors, if field investigation results warrant publication in a peer-reviewed journal or presentation at a scientific venue?

Not all of these crucial problems can be resolved before the field team arrives or the investigation concludes. However, they must be addressed, discussed openly, and agreed on as soon as possible.

Field Team Preparation

Many field investigations require laboratory support. Even if local laboratories are available and capable of processing and testing specimens, invited epidemiologists should immediately contact their laboratory counterparts within their agency to share details of the problem and discuss specimen types, collection, processing and testing, and potential basic or applied research questions that can be appropriately addressed and answered during the field investigation. Early enlistment of laboratory collaboration and support, at both the local level and at the invited agency, is crucial to the success of many field investigations.

The same early consideration applies to statistical support and contacting other health professionals, such as behavioral scientists, veterinarians, mammalogists, entomologists and vector-control specialists, environmental health specialists, and infection prevention and control practitioners, whose expertise can be crucial to a successful field investigation. The invited agency should consider including such professionals on the field team so that appropriate data and environmental specimens can be collected at the same time as other relevant epidemiologic information.

After the field team is chosen, the invited agency should take the following key measures to prepare the team:

  • Identify the team leader and the senior staff at the agency home base to whom the team leader should report.
  • Meet with all proposed field team members and home-based staff to review details of the public health problem, nature of the request for assistance, current knowledge of any suspected pathogen or disease, goals and objectives for the field investigation, and preliminarily agreed-on roles and responsibilities.
  • Arrange in advance an initial in-person meeting with the requestor (e.g., the State Epidemiologist) or persons designated by the requestor (e.g., local senior health officials and epidemiologists). This contact ensures that local authorities are not surprised by an unexpected arrival and underscores for all parties the need for advance planning and orderliness in the investigation, which will set the tone for the conduct of the investigation.
  • Write a memorandum for the record or to relevant key officials, which should be done by a senior member of the team before leaving for the field that summarizes the following points:
    • How and when the request was made.
    • What information the requesting health agency has provided.
    • What the agreed-on purpose is of the investigation.
    • What the commitments are of both the visiting team and requesting health officials.
    • Who will be members of the field team.
    • When the team is expected to arrive in the field.

This memorandum should be distributed to key personnel in the offices of the visiting team and the requesting host agency and to others who need to know. The memo serves not only as notification to everyone, but also as a method to prevent redundant responses. It will also identify expertise and resources from other programs that might contribute to the investigation. Even when a problem does not directly involve a state (for example, an investigation on tribal land or at a federal facility), an array of state and local officials typically are notified because of possible ramifications to populations in surrounding communities.

  • Review a basic checklist with each team member before departing to ensure they have materials and aids essential for field operations and have covered fundamental travel and logistic considerations. A partial list includes the following items:
    • Cell phones with key contacts
    • Laptop computers with appropriate software (e.g., Epi Info, SAS, or R)
    • Digital cameras
    • Credit cards
    • Travel and lodging reservations
  • Review with each team member before leaving the need for any necessary personal protective measures, such as vaccinations; antimalarial prophylaxis; antimicrobials or antivirals for postexposure prophylaxis; and personal protective equipment, including face masks or respirators, gloves, and gowns.
Initial In-Person Meeting of Field Team with Local Health Officials

The field team needs to keep in mind its role as consultant or collaborator. The guiding principle should be that the field team is there to provide help but not to take charge. Equally important is the need to balance the focus of the investigation with the competing priorities of the requesting jurisdiction. Although the immediate problem is the team’s sole concern, local health officials must continue to address a myriad of other local priorities and ongoing problems. The team needs to try to understand and appreciate the local viewpoint early in the investigation.

After arriving on site, the team should meet promptly with the official who requested assistance and his or her key staff. At this meeting, essential steps include the following items:

  • Review and update the status of the problem.
  • Identify or review the primary points of contact.
  • Identify a principal local collaborator who also can serve as what might be termed a “guardian angel” to facilitate and coordinate local contacts and team needs.
  • Identify or confirm availability of local resources (e.g., office space, clerical support, assistance for surveys, and laboratory support).
  • Create a method and schedule for the team to update local officials and home base.
  • Review sensitivities, including potential problems with institutions and individuals (e.g., hospitals, administrators, practitioners, and local public health staff) likely to be encountered during the investigation. Meeting the requesting official at the outset should ensure that key doors will be opened, rather than spending valuable time later in the investigation mending fences.

Because large outbreaks are likely to attract media attention, the presence of an experienced and knowledgeable public information officer (PIO) who can respond to public inquiries and regularly meet the media is invaluable. In the United States, the inviting local or state health department often has its own PIO who can serve as the media point person for the investigation. During the initial meeting, the local PIO should be identified. The field team should avoid direct contact with the news media and defer to local health officials. The field team essentially is working at the request and under the authority of the local health officials. The local officials not only know and appreciate the local situation, but also are the appropriate persons to comment on the investigation.

Management of Field Team Activities

Because of the potential complexity of field investigations, as well as the distracting circumstances under which they typically are conducted, the field team leader might want to take the following approaches to ensure the systematic and orderly progression of the investigation:

  • Maintain lists of necessary tasks, check off completed actions, and update the list at least daily.
  • Communicate frequently with other field team members, requesting official, and designated media contact, and hold a team meeting each day at a regularly scheduled time. Communicate with home base senior staff as often as needed.
  • Request additional help, without hesitation, as required by the circumstances.
  • Avoid setting a departure date in advance or succumbing to the pressure of team family members to return earlier to ensure the investigation will be completed.

Investigations of large and complex problems can be particularly challenging for field teams and require even more rigorous organization of field operations. The following practical pointers can help designated team leaders manage key aspects of the investigation:

  • Record the team’s decisions as they are made. This will help to ensure consistency and make the investigation reproducible, a consideration particularly important to case definitions and why certain criteria were used.
  • Remember the need for quality control measures, such as training and monitoring of data collectors and abstractors, including conducting error checks, validating data independently, and evaluating nonrespondents and missing records.
  • Resist collecting more data than are needed (e.g., excessive clinical details); focus on accomplishing the investigation objectives.
  • Write continually while the investigation is ongoing and before key details are forgotten.
    • Write the background section of the report.
    • Write the methods as they are being defined and developed by team members; keeping a decision log helps.
    • Maintain and retain an inventory of data files.
  • Assess data continually to determine when enough is known to make or update recommendations for control and prevention measures (see Chapter 11).
  • Make a special effort to maintain morale and to provide ongoing encouragement, positive reinforcement, and appreciation to participating investigators. Because field investigations are often difficult and associated with long hours and stress, the necessity might arise to give team members breaks or periods of rest to maintain productivity.

Occasionally, after some time in the field, an investigation does not yield definite results or it identifies additional questions that require one or more subsequent investigations to address. At that point, the team leader, in consultation with home base senior staff, should assess the team’s morale and capacity to persevere to determine whether the team should continue or a fresh team should prepare to extend the investigation.

Debriefing and Departure Meeting

After concluding the on-site field investigation, the team leader and the local senior official should organize a debriefing or departure meeting that includes the requestor, local collaborators, other key officials, and field team members. This meeting enables the team to debrief the requesting official and local partners about preliminary findings of the investigation, review preliminary recommendations, provide acknowledgments, and express appreciation to local hosts and collaborators. The team should obtain any additional names, titles, and street and email addresses for follow-up communications. If possible, the team should leave on site a preliminary report and commit to providing a complete written report within an agreed-on, specified time.

The departure meeting also might be the most appropriate occasion for planning follow-up activities with the requesting official and agency. Such activities include additional data collection, implementation and evaluation of control measures, analysis and maintenance of data collected during the investigation, plans for final reports and manuscripts (including discussion of authorship), and determination of who is responsible for each follow-up activity.

Drafting of Reports

Written summaries of the investigation include both preliminary and final reports. The preliminary report fulfills the immediate obligation to the requesting official and agency. It should summarize the methods used to conduct the investigation, preliminary epidemiologic and laboratory findings, recommendations, clearly delineated tasks and activities to be completed, and acknowledgments. In addition to the preliminary report, which optimally should be delivered to the requestor on departure or earlier, the team should prepare follow-up emails or letters to other principals (e.g., local health officials or coinvestigators) to inform them and to reinforce long-term relations.

The final reports with complete and final data should be written as quickly as possible—before team members are called out to another epidemiologic field investigation! In addition to a written final report, field team members should consider other methods for communicating the findings of the investigation. Options include formal presentations in person, teleconference, or videoconference at professional meetings; presentations or media communication to local communities affected by the public health event or to the general public; and written reports for public health bulletins intended for public health practitioners (e.g., CDC’s Morbidity and Mortality Weekly Report) or comprehensive articles for peer-reviewed journals.

Other Issues

Human Subjects and Privacy Concerns

Investigators must ensure that data collections comply with all requirements for human subjects protection. Field investigations conducted in response to outbreaks or other urgent public health events usually are determined to be public health response rather than research. However, an appropriate human subjects institutional review board must approve data collections determined to be research. Investigators must adhere to privacy requirements and confidentiality concerns throughout all phases of the field investigation. In addition to federal requirements regarding information privacy (see Chapter 13), each state has its own laws that cover privacy and confidentiality of information obtained during epidemiologic investigations (1). The stringency of these laws varies by state. Reports should be written in a manner that prevents identification of persons—and occasionally places—that were the subject of or implicated during the field investigation. After the investigation is complete, all records containing identifying information should be given to the inviting state or local jurisdiction for management according to the jurisdiction’s laws. In addition to protecting the privacy interests of persons who were subjects of the investigation, this approach also minimizes the likelihood that members of the invited field team would have information that might be subject to subpoena or freedom of information requests that normally would be denied by the state or local jurisdiction.

Suspected Bioterrorism

Suspected bioterrorism raises a spectrum of general operational and other practical considerations about the coordination of concurrent and overlapping investigations involving officials from both public health and law enforcement agencies (2) (see Chapter 24). A paramount operational consideration is determination of what sector and persons might be in charge of a given site; this is a function of several factors, including the extent to which information or evidence indicates that the site is a crime scene or has public health intervention implications in terms of preventing further exposures or identifying and managing potentially exposed persons.

In addition to determining who is in charge of the site, other key operational considerations are the approaches to interviewing persons who might be affected, either with active disease or with exposure, or who might be targeted by the criminal investigation as potential suspects, and to collecting biological samples from such persons and environmental samples from the site. For a concurrent investigation of suspected bioterrorism, interviews of affected persons are best conducted jointly by public health and law enforcement officials. Epidemiologists and criminal investigators must adhere to procedures that serve the interests of public health and safety and respect laws that safeguard the rights of persons, including those who are or might become suspects in a criminal investigation. When biological specimens and environmental samples are collected, field team members must recognize that physical information-gathering steps taken by law enforcement officials as part of an ongoing criminal investigation must adhere strictly to the process of establishing a chain of custody of evidence. A key purpose for this process is to ensure that specimens and samples presented as evidence during a criminal prosecution and trial in court can withstand challenge by the defense.

Incident Command Systems

Finally, regardless of whether an acute public health problem resulted from a natural or unintentional occurrence or from suspected bioterrorism, it might be serious enough to involve multiple jurisdictions (i.e., local, state, and federal) and multiple government agencies (e.g., emergency medical services, law enforcement, public health, or environmental health) and might require a standardized, coordinated response encompassing jurisdictions beyond public health. In the United States, ICS is a standardized command structure to manage incidents across jurisdictional boundaries (see Chapter 16). ICS enables personnel from different agencies and disciplines to work together in a common management structure with a clear chain of command or unified commands and provides logistical and administrative support to operational staff. In recent years, as part of bioterrorism preparedness, public health personnel at local, state, and federal levels have been engaged in emergency preparedness, and many are trained in ICS. In addition, ICS increasingly is used at all levels of public health to coordinate responses to large outbreaks or other acute situations with substantial political and public interest.

During the 2001 anthrax attacks in the United States, local, state, and federal public health field investigators worked with investigators from other agencies under an ICS set up at state and federal levels while the EOC was activated at CDC (3). In recent years, ICS and EOCs have been activated at CDC or states in response to pandemic influenza A(H1N1) (4) and outbreaks of Ebola virus disease (5) and Zika virus infection (6). Field investigators should be familiar with ICS and EOC, as well as their roles when a local EOC is activated. Use of ICS should simplify the defining of roles for all involved and optimize use of all resources and expertise across jurisdictions during management of emergency incidents.


Epidemiologic field investigations are important public health responses that can be enhanced through consideration of and adherence to certain key operational principles and practices. They will proceed more smoothly and productively if both inviters and invitees adequately address operational aspects before, during, and after the investigation.


The authors gratefully acknowledge the late Michael B. Gregg, Robert A. Gunn, and Jeffrey J. Sacks, whose work on this chapter in previous editions of this book contributed in part to this chapter.

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Page last reviewed: December 13, 2018