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EPID: Focus on Surveillance
Early Warning: The Necessary Beginning**

Stephen S. Morse, Ph.D.
Professor, Department of Epidemiology, Columbia University
Director, PREDICT, USAID Emerging Pandemic Threats program


Although most infections have been with us for a long time, new infections enter the human population or rapidly spread from a geographically limited area.  Infections that appear  suddenly or rapidly increase in number of cases or geographic range, are often called “emerging infections.”  Examples include human immunodeficiency virus/acquired immunodeficiency syndrome  (HIV/AIDS), SARS (Severe Acute Respiratory Syndrome), Nipah, and pandemic influenza (H1N1-2009).  Early warning surveillance is essential if we wish to prevent currently existing infectious diseases from increasing their range, or to prevent the next pandemic.  But we do not currently have adequate capabilities in place at virtually any level.  While the scientific issues are complex, I believe we have the scientific framework to begin, and that recent technological/scientific advances make this an opportune time to attack this problem.  Recommendations include: the need to develop capability both to identify (and rule out) common infectious diseases, as well as the unexpected or unusual; implementing the revised International Health Regulations; coordinating reporting systems and enhancing data sharing; encouraging interagency cooperation; maintaining personnel; strengthening research to refine microbial risk assessment and triggers for action, and continuing to educate policy makers on the importance of early warning surveillance.

Current realities

Since the middle of the last century we have witnessed the emergence of a number of “new” infections.  HIV/AIDS is a prime example: unknown until the late 1970s.  HIV has now become one of our greatest health concerns worldwide.  Others include SARS in 2003, hemolytic uremic syndrome, pandemic influenza (H1N1-2009), and Nipah, as well as increases in Hantaan (hemorrhagic fever with renal syndrome) in Asia as a consequence of land use changes.  Evidence suggests that the ancestor of HIV may have been introduced into the human population from another animal species (probably chimpanzees in central Africa), through hunting and butchering or handling of the meat.  A similar pattern (entry into the human population through handling of food animals) was seen with SARS and H5N1 avian influenza.
Emerging infections thus often already exist in other species or in geographically limited human populations, but are given an opportunity to come in contact with new human populations – often as a result of agricultural or environmental changes.  Important sources are therefore other vertebrate species, including wildlife.  Changes in ecology and land use can result in the emergence of apparently “new” infectious diseases (this fact also emphasizes the value of the “One Health” approach, linking human and animal health, including wildlife).  Infectious disease emergence is likely to rise with the increasing pace of ecological change and globalization continuing worldwide.  While many of these infections may be geographically limited, or currently have limited ability to transmit in the human population (e.g., H5N1 avian influenza), others may be transmissible from person-to-person (such as pandemic influenza, SARS, and HIV), and may be spread through human activities such as global travel and trade, sexual transmission, the healthcare system or the blood supply, and many others.
Early warning surveillance is essential if we wish to prevent currently existing infectious diseases from increasing their range, or to prevent the next pandemic (whether of an already known infection, such as influenza, or the “next HIV”).  However, the current reality is that we do not have adequate capabilities in place either for global surveillance of regionally or nationally important infectious diseases, or for new emerging infections.  Capabilities tend to be fragmented and disease-specific, with foodborne disease surveillance additionally fragmented and often separate.  The capability to identify, report, and differentiate both common and uncommon emerging infections is essential (Morse et al., 1996). 

Scientific opportunities and challenges

Effective systems of surveillance and response will therefore be obligatory (Morse, 2007).  Scientifically, we have unparalleled opportunities: a basic, if embryonic, scientific framework which can be built upon, and new capabilities that were unthinkable only a decade ago in communications, informatics, and diagnostic technology (Morse, 1995; Morse et al., 1996; Jones et al., 2008).  When ProMED-mail was initiated (1994), there was no World Wide Web, and many colleagues in remote areas could get e-mail access only via satellite uplinks.  Today, e-mail is widespread and almost half the world’s population has mobile phone access.  This makes it far easier to report outbreaks, to develop networks for surveillance and data sharing, and enables more rapid collaborative research.  In the response to the 2003 SARS outbreak, both epidemiologic data and basic research were shared rapidly through electronic networks, greatly accelerating the development of diagnostic tests and allowing effective public health response based on rapid case identification.  The widening availability of mobile phone networks now extends this reach even further, making disease event reporting possible in the community and in the field, even in locales without healthcare or public health infrastructure.  Similarly, advances in molecular technology have revolutionized diagnostic and identification capabilities (e.g., portable rapid molecular diagnostic tests, methods for genome sequencing of pathogens, and the computational power to compare these genomes and follow their geographic movement and evolution).  The U.S. Agency for International Development (USAID) recently developed an “Emerging Pandemic Threats” program (which includes an early warning component, PREDICT), an excellent example of what can be done to begin developing global capacity in early warning and response.
Among the challenges, in addition to the need to develop and implement sustainable capacity, emerging infections remain a moving target.  Environmental and ecological changes worldwide, and globalization, will increase both the opportunities for new infections to emerge and spread, and increase the complexity of the interactions.  It is therefore essential to develop a deeper understanding of the drivers, or factors, of emergence (Morse, 1995), and how to prevent their unintended consequences.  While we can identify many new microbes in other species, some of which have potential to become serious emerging infections, our ability to predict which infections are important and require special attention remains embryonic.  Therefore, we also need to develop better scientific approaches for risk assessment and risk reduction.  In short, we will require continuing development of our understanding of the drivers of emergence, and we must learn how to anticipate and avoid some of the currently unanticipated consequences of environmental changes and globalization.

Policy issues

Implementation and sustained political will remain the greatest challenges.  I suggest the following as specific steps towards developing a more effective system:
  • An effective system requires the ability to identify/rule out common infectious diseases, and to recognize and report the unexpected or unusual.  Governments should support the development of networks with these capabilities, including laboratory capacity.  To control costs, countries should pool resources and develop regional networks.
  • More specifically, implementing the revised International Health Regulations (IHR) is a step toward enhancing global surveillance capabilities.  Lessons learned from implementation should be used to improve the system. 
  • Coordinate reporting systems worldwide, and enhance data sharing (including ensuring compatible data standards).  As many emerging infections are zoonotic, this should include sharing between human and animal health resources (consider the “One Health” framework, including joint teams and co-located facilities).
  • Cooperation and coordination among the World Health Organization (WHO), Food and Agricultural Organization (FAO), and OIE (the World Organization for Animal Health), which has begun with avian influenza activities, should be extended and strengthened.
  • Skilled personnel is key; resources should be provided to recruit and train sufficient high-quality personnel and to ensure a stable career path for these workers.  Although (fortunately) pandemics and major emerging infectious disease outbreaks are rare, outbreaks of more common infectious diseases are sufficiently numerous to provide useful work in the periods between pandemics or major outbreaks. 
  • Educate clinicians, and also the general public, to recognize and report unusual outbreaks to appropriate authorities (in developing countries, where clinicians are in short supply, consider training local people to recognize and report.)
  • Research to continue improvements in diagnostics and data collection should be strongly supported by appropriate technical and funding agencies.
  • Refine microbial threat assessments and triggers for action.  This is a nascent area; examples include definitions in the new IHR and discussions in USAID, CDC, and elsewhere.  Technical and implementing agencies should strongly support continuing development of a useful risk assessment framework and defining triggers for action.
  • To encourage sustained funding and political will, continue educating policy makers on the importance of early warning surveillance.


Jones, K.E., Patel N.G., Levy M.A.,  Storeygard A., Balk D., Gittleman J.L., and Daszak P. (2008). Global trends in emerging infectious diseases. Nature. 451: 990-94.
Morse, S.S., Rosenberg B.H., Woodall J., and ProMED Steering Committee Drafting Subgroup. (1996). Global monitoring of emerging diseases: design for a demonstration program. Health Policy. 38:135-53.
Morse, S.S. (2007). Global infectious disease surveillance and health intelligence. Health Affairs. 26:1069-77.

From: Morse, S.S. (1995). Factors in the emergence of infectious diseases. [CDC] Emerging Infectious Diseases. 1:7-15.



Table 1: Factors in infectious disease emergence





Examples of specific factors

Examples of diseases

Ecological changes (including

Agriculture; dams, changes in

Schistosomiasis (dams); Rift Valley fever

those due to economic

water ecosystems;

(dams, irrigation); Argentine hemorrhagic

development and land use)


fever (agriculture); Hantaan (Korean


flood/drought; famine; climate

hemorrhagic fever) (agriculture);



hantavirus pulmonary syndrome, southwestern US, 1993 (weather anomalies)

Human demographics,

Societal events: Population

Introduction of HIV; spread of dengue; spread


growth and migration

of HIV and other sexually transmitted


(movement from rural areas



to cities); war or civil conflict;



urban decay; sexual behavior;



intravenous drug use; use of



high-density facilities


International travel and

Worldwide movement of goods

“Airport” malaria; dissemination of mosquito


and people; air travel

vectors; ratborne hantaviruses; introduction of cholera into South America;



dissemination of O139 V. cholerae

Technology and industry

Globalization of food supplies;

Hemolytic uremic syndrome (E. coli


changes in food processing

contamination of hamburger meat), bovine


and packaging; organ or

spongiform encephalopathy;


tissue transplantation; drugs

transfusion-associated hepatitis (hepatitis


causing immunosuppression;

B, C), opportunistic infections in


widespread use of antibiotics

immunosuppressed patients, Creutzfeldt-Jakob disease from



contaminated batches of human growth hormone (medical technology)

Microbial adaptation and

Microbial evolution, response to

Antibiotic-resistant bacteria, “antigenic drift”


selection in environment

in influenza virus

Breakdown in public health

Curtailment or reduction in

Resurgence of tuberculosis in the United


prevention programs;

States; cholera in refugee camps in Africa;


inadequate sanitation and

resurgence of diphtheria in the former


vector control measures

Soviet Union

** A policy position paper prepared for presentation at the conference on Emerging and Persistent Infectious Diseases (EPID): Focus on Surveillance convened by the Institute on Science for Global Policy (ISGP) Oct. 17-20, 2010, at Airlie Conference Center, Warrenton, Va.

Debate summary

The following summary is based on notes recorded by the ISGP staff during the not-for-attribution debate of the policy position paper prepared by Prof. Stephen Morse (see above).  Prof. Morse initiated the debate with a 5-minute statement of his views and then actively engaged the conference participants, including other authors, throughout the remainder of the 90-minute period.  This Debate Summary represents the ISGP’s best effort to accurately capture the comments offered and questions posed by all participants, as well as those responses made by Prof. Morse.  Given the not-for-attribution format of the debate, the views comprising this summary do not necessarily represent the views of Prof. Morse, as evidenced by his policy position paper.  Rather, it is, and should be read as, an overview of the areas of agreement and disagreement that emerged from all those participating in the critical debate.

Debate conclusions

  • Strong support was expressed for enhancing global leadership and coordination for activities addressing infectious disease surveillance.  To make this a reality, it is imperative that governmental agencies and international organizations significantly improve the coordination of their efforts.
  • Capacity building for infectious disease surveillance was deemed essential, particularly with respect to strengthening laboratory capacity, epidemiological capacity, and regional networks.
  • Scientific and public health communities must learn to better convey to government officials and the public the results emerging from the analyses of information obtained from infectious disease surveillance.  Engaging the media is viewed as essential to communicating credible information that both supports government officials and fosters public trust by sharing relevant information that educates the citizenry.
  • Rigorous analysis and modeling of surveillance data are fundamentally essential to formulate the type of information needed by policy makers, especially with respect to justifying the public resources devoted to disease surveillance.
  • Country ownership with respect to infectious disease surveillance must be fostered through bottom-up approaches with links to regional networks to strengthen the sustainability of these programs and create more effective surveillance priorities.
  • Political, economic, and technical barriers to sharing data from infectious disease surveillance across international borders should be significantly eased.

Current realities

Prominent intergovernmental organizations (e.g., the United Nations [U.N.] and the World Health Organization [WHO]) are increasingly focused on infectious disease control worldwide through an array of programs, directives, and activities, such as the Millennium Development Goals, the WHO’s International Health Regulations (IHR), and the Technical Area for Health Surveillance and Disease Prevention and Control of the Pan American Health Organization.  Of central importance to many of these initiatives is the expansion and improvement of infectious disease surveillance.  Yet, deficiencies remain in terms of effective coordination of roles and innovative leadership among domestic agencies, departments, and commissions, as well as between international organizations.
While wealthier nations maintain extensive laboratory facilities, epidemiological activities, and regional networks, less-wealthy regions of the world are often dramatically less well equipped in these arenas.  This dichotomy is paradoxical, as less-wealthy areas possess a disproportionately strong need for these capabilities given that the global burden of infectious diseases is concentrated in these regions.  Obviously, a scarcity of resources and myriad competing disease and health needs are the primary reasons that less-wealthy nations are deficient in these arenas.
Data transfer (i.e., the sharing of data across agencies and/or geographic boundaries) is increasingly recognized as playing an integral role in infectious disease control.  The importance of data transfer has been highlighted for its role in prevention, accurately identifying outbreaks, and identifying resources for remediation.  In addition, data sharing can mitigate the duplication of surveillance efforts that often occurs when different domestic agencies or national governments are not working in concert with one another.
A number of “new” diseases hass emerged since the middle of the last century, such as human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), human monkeypox, Severe Acute Respiratory Syndrome (SARS), and Lyme disease.  The number of “new” diseases is expected to continue to increase due to the effects of ecological change and rapid globalization.  Endemic infectious diseases are expected to remain problematic since it is difficult to control infectious diseases even when a cure is known.  This is attributable to impediments such as the continued presence, and potential of transmission of, infectious diseases in animal reservoirs and vectors (e.g., Salmonella and malaria), the continued reservoir of disease in human populations (e.g., tuberculosis), and the influence of ongoing socioeconomic and political constraints.  In line with this growth in the total number of infectious diseases (“new” and endemic), surveillance needs will expand in the short and long term.
Prevention is an important component of emerging and re-emerging infectious disease control, and early warning surveillance is integral to the success of any prevention program.  Timely recognition of emerging infections is needed so that they may be promptly investigated and control plans outlined prior to large-scale outbreaks and/or pandemics.  Prevention also relies on a thorough understanding of trends in incidence and distribution of known infectious agents — information that is a product of good surveillance data.   
Even when surveillance data exists, it is not always acknowledged or used in a timely fashion.  The history of HIV/AIDS provides a modern lesson on the importance of giving early attention to surveillance data.  In the 1960s, a surge in opportunistic infections such as cryptococcal meningitis, Kaposi’s sarcoma, tuberculosis, and specific forms of pneumonia was observed in parts of Africa.  Although it is now known that this constellation of infections was directly related to HIV/AIDS, at the time the information was not viewed in a holistic manner that could have revealed the disease’s emergence.  Even when reports emerged of similar symptoms in other parts of the world (including clusters of warning signs in gay communities, which led to the initial name, Gay-Related Immune Deficiency (GRID), response was slow.  It was not until the disease was better understood and outbreaks recognized that public health and political support for HIV/AIDS control fully mobilized.  By that point, however, the disease had firmly taken root throughout the world and a global epidemic ensued. 

Scientific opportunities and challenges

The need for improved laboratory facilities and expanded epidemiological training and expertise in less-wealthy nations represents both infrastructural and scientific challenges to emerging and persistent infectious disease control.  From an infrastructural standpoint, a need for improvements in terms of the coordination of resources, logistical capabilities, and policy processes was stressed.  From a scientific perspective, technological advancements are likely to mitigate some infrastructural concerns over time, although this was generally viewed as a long-term endeavor that requires substantial research and investment. 
Although the technology for rapid data transfer has markedly improved in the last decade, it was contended that significant progress in this area is needed.  In addition, it was argued that important obstacles remain in terms of breaking down the political and economic barriers that impede data sharing.  Political and economic issues that were raised as specific challenges included the publicly acceptable extent of individual privacy, country security, and conflicts regarding data ownership.
As technologies advance, new windows of opportunity for enhancing infectious disease surveillance emerge.  This positive change was highlighted by examples of the potential value of infectious disease prediction based on the modeling of hotspots and infections.
Although early warning surveillance is widely recognized as a fundamental component of infectious disease prevention, many challenges remain.  Monitoring must be consistent, comprehensive, and accurate for early warning to be effective.  Moreover, new techniques are needed to help identify the early appearance of “new” diseases before they escalate within a population.  However, early warning surveillance should not be considered a silver bullet for infectious disease control.  Public health communities can never be fully prepared to prevent widespread transmission of infectious diseases because what is needed to avert a crisis is not always known in advance, particularly in the case of emerging diseases.  However, given that early warning systems often provide critically important new information, they should not only continue to be used extensively, but research into how their effectiveness can be improved also needs to be expanded.

Policy issues

There was general consensus on the need for significantly improving the quality of global leadership and coordination of disease surveillance designed to protect the public’s health.  However, there was clear disagreement on who should take the lead in improving agency coordination and in defining leadership responsibilities.  While some touted the WHO as the primary choice for this role (citing improvements in the WHO’s ability to act proactively rather than reactively), others argued that agencies like the WHO often talk about coordination without effectively improving it.  In addition, coordination between international agencies was raised as a critical issue, especially with respect to the barriers impeding coordination caused by each organization’s budgetary and political constraints.  Candid dialogues among these international organizations concerning their funding and policy priorities were viewed as essential steps to any effective coordination on disease surveillance.
Capacity building for infectious disease surveillance was unanimously considered an essential need.  Three fundamental areas for immediate amelioration were identified.  The first was to expand and enhance laboratory capacity for disease confirmation (particularly in less-wealthy countries).  The second focused on improving the national epidemiological capacity for better targeting where pathogens are located and to treat those who are directly affected.  This can be accomplished in a variety of ways, such as through in-country training.  The third recommendation was to create regional networks to increase coordination and cooperation among countries as well as to expand the opportunities for obtaining additional funding in resource-poor areas.  These three recommendations were viewed as parts of a general, ongoing process that would take time to develop and implement. 
There was also consensus on the critical need to improve infectious disease messaging to the public (i.e., enhancing the effectiveness with which both the scientific and public health communities convey accurate and timely information on the potential impact and/or risks of diseases).  It was noted that although improvements have been observed in this arena, significant gains are urgently needed.  There was agreement that the greatest challenge is the difficulty of communicating enough relevant information, including imparting an accurate understanding of the degree of uncertainty associated with almost all disease surveillance information.  The apparent absence of public trust in the information provided by government agencies concerning the recent H1N1 outbreak was considered a prime example of the need for change in communication approaches.
It was noted that messages are undermined when risks are either overplayed or do not materialize, regardless of whether epidemics are mitigated through the appropriate interventions.  Public confusion and even mistrust is created when the scientific and public health communities do not present uniform, readily understandable information.  This situation often occurs when conflicting information is presented to the public.  A common example involves the distribution of conflicting information based on the use of different models in the analysis of disease surveillance data.  It was suggested that these communities work together to provide authenticated information to the public from the outset of a disease outbreak and to appropriately engage the credible media.  It is critical that officials identify any incorrect or false information provided by unofficial sources (as was routinely witnessed in the 1990s) and educate the public concerning the real long-term risks from infectious diseases, even when crises are averted.
Discussions also noted that the value of disease surveillance data is practically realized only after rigorous analysis and interpretation using the appropriate modeling methods.  From this perspective, data analysis and modeling were viewed as integral to obtaining the information required to effectively inform the policy-making process.  These same results can be useful in identifying the societal benefits needed to justify the resources spent on disease surveillance itself.
It was strongly agreed that country ownership with respect to designing and implementing infectious disease surveillance programs should be fostered.  A bottom-up approach was widely endorsed, with strong connections to regional networks.  It was voiced that sustainability and effective agendas will be strengthened when less-wealthy countries take responsibility for their own health destinies.  Within this context, it was asserted that less-wealthy countries should invest more of their own gross domestic products into disease surveillance and other actions needed to effectively respond to emerging and persistent infectious diseases.  These investments would permit each country to set its own priorities rather than rely strictly on funds from donor organizations that come with preset goals, which may not be consistent with what a country wants or needs. 
A vigorous debate focused on the need to resolve conflicts over the sharing of disease surveillance data among agencies, international organizations, and across international borders.  The need for facilitating data sharing was supported by several examples, mostly involving the consequences of delays in transferring scientifically credible information to policy makers.  In the case of the recent H1N1 epidemic, only two scientific papers were initially available on projecting the spread of the disease.  It was argued that correcting this problem would involve a mindset shift for scientists who would have to sacrifice some assurance of accuracy (uncertainty of conclusions) in favor of expediency so that policy makers would have the information they need to make timely decisions. 
In addition, it was noted that information sharing is greatly impeded by vastly different national, political, and economic concerns.  Countries are frequently hesitant to share information because the perceived political and social risks outweigh the potential benefits.  For example, countries may be concerned that the dissemination of their disease surveillance data will cause security breaches, especially with respect to the methods used to obtain that information.  Similarly, they may fear economic fallout (e.g., reduced tourism or revenue losses caused by the dissemination of proprietary data).  While no consensus was established on how much information should be shared across borders, it was agreed that significant improvements in how this information is shared are needed to make disease surveillance a viable tool to protect human health, both domestically and internationally. 
Although it was agreed that surveillance data do not guarantee that prevention will be possible, it was emphasized that no system designed to protect human health can function properly without effective surveillance.  Additionally, it was recommended that research be fostered with respect to developing new ways to improve disease tracking processes and to identify more precise applications of the data.
Support was raised for implementation of the revised International Health Regulations for emerging and persistent infectious disease surveillance objectives.  This support was challenged by the argument that although the IHRs are important, they are not useful for early warning purposes.
Although much emphasis has been placed on the practice of surveillance for infectious diseases, specifically to ensure that monitoring obtains the appropriate data, there were those who stressed that the data gathering process is only the first step in surveillance.  The data must also be analyzed and modeled in ways that properly inform the decision-making processes.  From a policy perspective, infectious disease surveillance information must be distilled so that individuals in leadership positions can understand what the data mean and effectively use this knowledge to allocate financial and human resources appropriately.
While the rise of HIV/AIDS exemplifies the importance of practicing infectious disease surveillance and heeding the warning signs that surveillance provides, it was emphasized that surveillance data alone does not ensure that crises will be averted.  With so much information collected and distributed, it is often difficult for researchers to effectively decipher what pieces are important and to predict which diseases will escalate.  This abundance of information makes it especially challenging for policy makers to decide where their finite resources should be allocated.  For many reasons, including politically motivated priorities, policy makers often wait until an infectious disease threat has fully materialized before responding.  Discovering the best way to balance surveillance reports and competing social and political priorities is an obvious goal for all communities involved in disease surveillance.

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