Executive Summary

Disease-causing microbes have threatened human health for centuries. The Institute of Medicine's Committee on Emerging Microbial Threats to Health believes that this threat will continue and may even intensify in coming years. The committee's report, which is summarized here, describes key elements responsible for the emergence of infectious diseases; it also presents recommendations that, if appropriately implemented, should allow the United States to be better prepared to recognize and respond rapidly to these public health threats.

What are the factors, operating both singly and in combination, that are contributing to the emergence of such pathogens? Like other living organisms, infectious agents are subject to genetic change and evolution. This quality is manifested by their ability to infect new hosts, by alterations in their susceptibility to antimicrobial drugs, and by changes in their response to host immunity. Alterations can also occur in geographic ranges; in some cases, modern transport has led to rapid movement of agents throughout the world. The human host has changed as well. We have adopted new types of personal behavior and new food-processing methods that may enhance transmission of some microbes. New diseases and modern medical treatments may result in immunosuppression and thus increase susceptibility to pathogenic microorganisms. Moreover, in recent years, the human population has experienced rapid growth and increased mobility resulting in intrusion into new ecological settings. These changes in infectious agents and human populations favor exposure to new pathogens and more efficient transmission of recognized microbes.

Other changes are also affecting disease emergence. For example, some infectious agents exist in vertebrate reservoirs such as wild animals. These



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Emerging Infections: Microbial Threats to Health in the United States Executive Summary Disease-causing microbes have threatened human health for centuries. The Institute of Medicine's Committee on Emerging Microbial Threats to Health believes that this threat will continue and may even intensify in coming years. The committee's report, which is summarized here, describes key elements responsible for the emergence of infectious diseases; it also presents recommendations that, if appropriately implemented, should allow the United States to be better prepared to recognize and respond rapidly to these public health threats. What are the factors, operating both singly and in combination, that are contributing to the emergence of such pathogens? Like other living organisms, infectious agents are subject to genetic change and evolution. This quality is manifested by their ability to infect new hosts, by alterations in their susceptibility to antimicrobial drugs, and by changes in their response to host immunity. Alterations can also occur in geographic ranges; in some cases, modern transport has led to rapid movement of agents throughout the world. The human host has changed as well. We have adopted new types of personal behavior and new food-processing methods that may enhance transmission of some microbes. New diseases and modern medical treatments may result in immunosuppression and thus increase susceptibility to pathogenic microorganisms. Moreover, in recent years, the human population has experienced rapid growth and increased mobility resulting in intrusion into new ecological settings. These changes in infectious agents and human populations favor exposure to new pathogens and more efficient transmission of recognized microbes. Other changes are also affecting disease emergence. For example, some infectious agents exist in vertebrate reservoirs such as wild animals. These

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Emerging Infections: Microbial Threats to Health in the United States agents, in some instances, have migrated and increased in number. Some microbes that are transmitted by insects or other vectors exhibit these characteristics as well; in addition, they may have become resistant to pesticides, which impedes efforts at control. Finally, the environment has changed and will continue to change. Humanity has altered the world's ecology through deforestation, urbanization, and industrialization, which some believe may lead to global climate change. Moreover, the world periodically experiences civil unrest and war, which can lead to regional breakdowns in sanitation, allowing microbes to flourish. Individually and collectively, these and other factors lead to the emergence and reemergence of microbial pathogens. Infectious diseases remain the major cause of death worldwide (World Health Organization, 1992) and will not be conquered during our lifetimes. With the application of new scientific knowledge, well-planned intervention strategies, adequate resources, and political will, many of these diseases may be prevented by immunization, contained by the use of drugs or vector-control methods, and, in a very few cases, even eradicated—but the majority are likely to persevere. We can also be confident that new diseases will emerge, although it is impossible to predict their individual emergence in time and place. The committee believes that there are steps that can and must be taken to prepare for these eventualities. Its recommendations address both the recognition of and interventions against emerging infectious diseases. RECOGNITION The key to recognizing new or emerging infectious diseases, and to tracking the prevalence of more established ones, is surveillance. A well-designed, well-implemented surveillance program can detect unusual clusters of disease, document the geographic and demographic spread of an outbreak, and estimate the magnitude of the problem. It can also help to describe the natural history of a disease, identify factors responsible for emergence, facilitate laboratory and epidemiological research, and assess the success of specific intervention efforts. The importance of surveillance to the detection and control of emerging microbial threats cannot be overemphasized. Poor surveillance leaves policymakers and medical and public health professionals with no basis for developing and implementing policies to control the spread of infectious diseases. The committee does not know whether the impact of human immunodeficiency virus (HIV) disease could have been limited if there had been an effective global infectious disease surveillance system in place in the late 1960s or early 1970s. However, without such a system in place, we would have little chance for early detection of emerging diseases in the future.

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Emerging Infections: Microbial Threats to Health in the United States Current U.S. disease surveillance efforts include both domestic and international components. Domestically, the bulk of federal disease-reporting requirements (individual states also require reporting) are implemented through the National Notifiable Diseases Surveillance System, established in 1961 and administered by the Centers for Disease Control (CDC). The CDC also operates a domestic influenza surveillance program that supplies epidemiological information to public health officials, physicians, the media, and the public. Notwithstanding such programs, the United States has no comprehensive national system for detecting outbreaks of infectious disease (except for food-and waterborne diseases). Outbreaks of any disease that is not on CDC's current list of notifiable illnesses may go undetected or may be detected only after an outbreak is well under way. Emerging infectious diseases, with the exception of those reportable diseases that reemerge, also are not detected through established surveillance activities. Another problem is the lack of coordination among the various U.S. government agencies, or between government agencies and private organizations, involved in these efforts. The effectiveness of U.S. domestic surveillance could be vastly improved by designating an agency or central coordinating body as a focus for such activities. The committee recommends the development and implementation of strategies that would strengthen state and federal efforts in U.S. surveillance. Strategy development could be a function of the Centers for Disease Control (CDC). Alternatively, the strategy development and coordination functions could be assigned to a federal coordinating body (e.g., a subcommittee of the Federal Coordinating Council for Science, Engineering, and Technology's [FCCSET] Committee on Life Sciences and Health,1 specifically constituted to address this issue. Implementation of the strategies would be assigned to the appropriate federal agencies (e.g., CDC, National Institutes of Health, U.S. Department of Agriculture). Approaches for consideration could include simplifying current reporting forms and procedures, establishing a telephone hotline by which physicians could report unusual syndromes, and using electronic patient data collected by insurance companies to assist in infectious disease surveillance. 1   The FCCSET is a federally appointed body of experts that serve on seven standing committees and act as a mechanism for coordinating science, engineering, technology, and related activities of the federal government that involve more than one agency. In addition to conducting cross-cutting analyses of programs and budgets, the various committees and their subcommittees (interagency working groups) examine wide-ranging topics with the goal of reaching consensus on fundamental assumptions and procedures that can guide the actions of the participating agencies in achieving their mission objectives more effectively.

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Emerging Infections: Microbial Threats to Health in the United States A second major domestic disease surveillance effort is the National Nosocomial Infections Surveillance System (NNISS), which currently gathers data from approximately 120 sentinel hospitals and is operated by CDC's Hospital Infection Program. Although nosocomial diseases constitute an important share of the burden of disease in this country, the system has several major limitations. For example, it cannot correct for differences among participating hospitals in diagnostic testing, intensity of surveillance, and provisions for postdischarge surveillance. The requirement that NNISS member hospitals have at least 100 beds, and the relatively small sample of hospitals that are included in the system, are also potential sources of bias. Current plans call for improvements in the dissemination of NNISS data, the inclusion of a surveillance component for immunosuppressed patients, and the addition of more sentinel hospitals, among other efforts. The committee recommends that additional resources be allocated to the Centers for Disease Control to enhance the National Nosocomial Infections Surveillance System (NNISS) in the following ways: Include data on antiviral drug resistance. Include information on morbidity and mortality from nosocomial infections. Increase the number of NNISS member hospitals. Strive to make NNISS member hospitals more representative of all U.S. hospitals. Evaluate the sensitivity and specificity of nosocomial infection surveillance activities performed in NNISS member hospitals. Determine the reliability of antimicrobial susceptibility testing performed in NNISS member hospitals. Considerable effort and resources are being expended on the various surveillance activities in which U.S. government agencies and the private sector participate. Much of this information, however, is not readily accessible. There is currently no single database from which a physician, researcher, health care worker, public health official, or other interested party can obtain information on disease incidence, antibiotic drug resistance, drug and vaccine availability, or other topics that might be relevant to infectious disease surveillance, prevention, treatment, and control. The committee recommends that the U.S. Public Health Service develop a comprehensive, computerized infectious disease database. Such a database might consolidate information from more specialized sources, such as the National Nosocomial Infections Surveillance System (NNISS), the National Electronic Telecommunications System for Surveillance (NETSS), and the influenza surveillance system; it could also include

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Emerging Infections: Microbial Threats to Health in the United States additional information, such as vaccine and drug availability. As an alternative, expansion of currently available databases and provisions for easy access to these sources should be aggressively pursued. The implementation of such a program should also encompass expanded efforts to inform physicians, public health workers, clinical laboratories, and other relevant target groups of the availability of this information. U.S.-supported overseas laboratories have played a historic role in the discovery and monitoring of infectious diseases. The United States and other nations first created these disease surveillance posts, many of them in tropical and subtropical countries, to protect the health of their citizens who were sent to settle or administer recently acquired territory. After World War II, there was a second blossoming of such surveillance activities. The Fogarty International Center was established, as were several overseas laboratories staffed by Department of Defense personnel. Privately funded activities, like those of the Rockefeller Foundation Virus Program, were also important contributors to infectious disease surveillance at the international level. Over the past two decades, a number of these facilities have been closed or are no longer operating with U.S. oversight. Nevertheless, although its efforts are substantially reduced from previous levels, the United States still maintains an international presence in infectious disease surveillance and research. As is the case in related domestic efforts, however, international infectious disease surveillance activities undertaken by U.S. government agencies remain largely uncoordinated and in need of a strategy to focus them in appropriate areas, such as emerging diseases. The committee recommends that international infectious disease surveillance activities of U.S. government agencies be coordinated by the Centers for Disease Control (CDC). To provide the necessary link between U.S. domestic and international surveillance efforts, the body that is established for this purpose should be the same as that suggested earlier in the recommendation on domestic surveillance. Alternatively, a federal coordinating body (e.g., a subcommittee of the Federal Coordinating Council for Science, Engineering, and Technology's [FCCSET] Committee on Life Sciences and Health, specifically constituted to address this issue) could be assigned the coordinating function. Implementation of surveillance activities, however, should remain with the appropriate federal agencies (e.g., the CDC, Department of Defense, National Institutes of Health, U.S. Department of Agriculture). The efforts of multilateral international organizations, such as the World Health Organization (WHO), are critical in coordinating infectious disease

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Emerging Infections: Microbial Threats to Health in the United States surveillance worldwide. The WHO is a focal point for surveillance data on several globally important infectious diseases; it also operates a number of surveillance networks around the world, composed of selected ''collaborating centers," that report and investigate outbreaks of specific diseases, such as influenza and HIV disease. The WHO is often involved in early investigative efforts related to newly emerging or reemerging infectious diseases (e.g., Ebola, Lassa, yellow, and dengue fevers). Current U.S. and international surveillance efforts are certainly of great value in detecting known infectious and noninfectious diseases. They fall short, however, in their ability to detect emerging infectious diseases. There has been no effort to develop and implement a global program of surveillance for emerging diseases or disease agents. The committee believes that an effective global surveillance network on emerging infectious diseases is an essential element in efforts to combat microbial threats and that it should have four basic components: a mechanism for detecting (using clinical presentation as the criterion) clusters of new or unusual diseases or syndromes; laboratories capable of identifying and characterizing infectious agents; an information system to analyze reportable occurrences and disseminate summary data; and a response mechanism to provide feedback to reporting agencies and individuals and, if necessary, to mobilize investigative and control efforts of local and international agencies. A global surveillance network should also comprise such elements as locally staffed surveillance centers to promote regional self-reliance and train local personnel, links to academic centers and other regional facilities involved in basic research, a clinical arm for hospital-based surveillance and drug and vaccine trials, an effective specimen collection and transport system, and an active system of data analysis and dissemination, with feedback to those providing data. Models that may offer useful lessons for the design of such a network include the WHO's global influenza surveillance network and its collaborating centers for specific diseases, the Pan American Health Organization's (PAHO) polio eradication program, and earlier infectious disease initiatives, such as the WHO smallpox eradication campaign and the Rockefeller virus program. The committee recommends that the United States take the lead in promoting the development and implementation of a comprehensive global infectious disease surveillance system. Such an effort could be undertaken through the U.S. representatives to the World Health Assembly. The system should capitalize on the lessons from past successes and on

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Emerging Infections: Microbial Threats to Health in the United States the infrastructure, momentum, and accomplishments of existing international networks, expanding and diversifying surveillance efforts to include known diseases as well as newly recognized ones. This effort, of necessity, will be multinational and will require regional and global coordination, advice, and resources from participating nations. INTERVENTION The recognition of an emerging infectious disease is the first component of response, but what follows that recognition may, in fact, determine the final impact of an emerging disease on the public's health. Effective intervention against such diseases necessitates coordinated efforts by a variety of individuals, government agencies, and private organizations. The committee believes that the current U.S. capability for responding to microbial threats to health lacks organization and resources. The recommendations in the subsections below address these deficiencies. The U.S. Public Health System In the United States, principal responsibility for protecting the public's health rests with the 50 state health departments, or their counterparts, and more than 3,000 local health agencies. At the federal level, the national focus for disease assessment is the CDC. A 1988 Institute of Medicine (IOM) report, The Future of Public Health, described the U.S. public health system as being in a state of disarray that has produced "a hodgepodge of fractionated interests and programs, organizational turmoil among new agencies, and well-intended but unbalanced appropriations—without coherent direction by well-qualified professionals." It is the committee's view that there has been little positive change in the U.S. public health system since the release of that report. The recent rapid increases in the incidence of measles and tuberculosis are evidence of these continuing problems. Steps have now been taken to address inadequacies in programs for these diseases, but these responses are reactive, not proactive. It is the committee's belief that the prevention of infectious diseases must be stressed if the health of this nation's inhabitants is to be maintained or improved. Greater efforts directed at the recognition of and responses to emerging public health problems, particularly emerging infectious diseases, would help achieve this goal. The problems of the U.S. public health system are attracting the attention of policymakers. Recently, the U.S. Public Health Service published a set of strategies for improving disease surveillance, epidemiology, and communication, three key areas of weakness cited in the 1988 IOM report. A number of these strategies are particularly relevant to the emerging disease

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Emerging Infections: Microbial Threats to Health in the United States issues addressed by this committee. If implemented, these suggested improvements will, in part, respond to recommendations made in this report. Research and Training Many of the factors that are responsible for, or that contribute to, the emergence of infectious diseases are now known. Yet our understanding of these factors and of how they interact is incomplete. We are a long way from being able to develop strategies to anticipate the emergence of infectious diseases and to prevent them from becoming significant threats to health. The committee nevertheless sees this kind of development as a desirable long-term goal and concludes that research to achieve it should be strongly encouraged. In July 1991, the National Institute of Allergy and Infectious Diseases (NIAID) convened a task force on microbiology and infectious diseases to identify promising research opportunities and to recommend research strategies for future NIAID programs. The committee has reviewed the January 1992 NIAID task force report, and it believes that its studies and the work of the task force are complementary. Consequently, the committee fully supports the conclusions and recommendations of the NIAID task force. The committee recommends the expansion and coordination of National Institutes of Health-supported research on the agent, host, vector, and environmental factors that lead to emergence of infectious diseases. Such research should include studies on the agents and their biology, pathogenesis, and evolution; vectors and their control; vaccines; and antimicrobial drugs. One approach might be to issue a request for proposals (RFP) to address specific factors related to infectious disease emergence. Several programs support research and training related to the epidemiology, prevention, and control of infectious diseases. Whether they involve U.S. or foreign scientists, have a broad or narrow focus, all of these programs contribute to the international capability to recognize and respond to emerging infectious diseases. The Rockefeller Foundation's International Clinical Epidemiology Network trains junior medical school faculty from developing countries in the discipline of epidemiology. After their training, these individuals return to their home countries, where they become part of a medical school-based training unit that helps evaluate the availability, effectiveness, and efficacy of health care. Recently, the NIAID consolidated the International Collaboration in Infectious Disease Research (which allows U.S. scientists to develop overseas work experience) and the Tropical Disease Research Units (which focus on six diseases cited by the WHO as major health problems in the tropics)

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Emerging Infections: Microbial Threats to Health in the United States programs, as well as several other efforts in international health under one new initiative, the International Centers for Tropical Disease Research. The CDC currently supports research and training in the area of infectious diseases through its National Center for Infectious Diseases. Earlier efforts by the agency, however, may have valuable components that deserve revisiting. For example, from the mid-1960s to the early 1970s, the CDC administered an extramural program that awarded grants to academic and other institutions for research in infectious disease prevention and control. The committee has concluded that this now defunct program filled a need for support in a critical area of research. The committee recommends increased research on surveillance methods and applied control strategies; on the costs and benefits of prevention, control, and treatment of infectious disease; and on the development and evaluation of diagnostic tests for infectious diseases. Reinstating and expanding (both in size and scope) the extramural grant program at the Centers for Disease Control, which ceased in 1973, would be one important step in this direction. Similarly, the Food and Drug Administration's (FDA) extramural grant program should be expanded to place greater emphasis on the development of improved laboratory tests for detecting emerging pathogens in food. An adequate supply of well-trained, experienced epidemiologists is critical to the nation's surveillance efforts. CDC's Epidemic Intelligence Service (EIS) provides health professionals with two years of training and field experience in public health epidemiology. The EIS is the model as well for another evolving program, the joint CDC/WHO Field Epidemiology Training Program (FETP), which places field-oriented epidemiologists in countries that need to develop and implement disease prevention and control programs. Current and former EIS officers and FETP graduates are important sources of information on emerging diseases and constitute a personnel nucleus for a global surveillance network. The distribution of these epidemiologists, however, is restricted because of the limited number of program graduates each year. The committee recommends the domestic and global expansion of the Center for Disease Control's (CDC) Epidemic Intelligence Service program and continued support for CDC's role in the Field Epidemiology Training Program. The seven overseas medical research laboratories maintained by the U.S. Department of Defense are the most broadly based international facilities of their kind supported by the United States. In addition to being well situated

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Emerging Infections: Microbial Threats to Health in the United States to recognize and study emerging disease threats, the facilities are valuable sites for testing new drugs and vaccines, because they are located in areas of the world in which the diseases of interest are endemic. The committee recommends continued support—at a minimum, at their current level of funding—of Department of Defense overseas infectious disease laboratories. In the area of training, previous studies have noted shortages of medical entomologists, clinical specialists trained in tropical disease diagnosis, prevention, and control, biomedical researchers, and public health specialists. The National Health Service Corps scholarship program, created in 1972, underwrites the costs of medical education in return for medical service in underserved areas of the United States. The committee is unaware of any similar program directed at individuals who wish to train for careers in public health and related disciplines. Such a program might attract those who otherwise would not consider careers in public health. The committee recommends that Congress consider legislation to fund a program, modeled on the National Health Service Corps, for training in public health and related disciplines, such as epidemiology, infectious diseases, and medical entomology. Vaccine and Drug Development Vaccines and antimicrobial drugs have led to significant improvements in public health in the United States and in many other nations during the latter half of this century. Despite this encouraging history, the committee is concerned that many of the vaccines and drugs available today are the same ones that have been used for decades. It believes that there is a need to review the present vaccine and drug armamentaria with a view toward improving availability and "surge" capacity, as well as safety and efficacy. VACCINES Advances in immunology, molecular biology, biochemistry, and drug delivery systems have stimulated major new initiatives in vaccine development. As a result, the generation of vaccines that will come into use in the next decade is likely to be different from previous vaccines. For example, some will contain more than one highly purified antigen and will rely on new delivery methods. For all their potential, however, vaccines should not be viewed as magic bullets for defeating emerging microbial threats to health. The potential value of vaccination and the speed with which vaccines

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Emerging Infections: Microbial Threats to Health in the United States can be developed depend on many factors, such as the existing scientific knowledge of the agent (or a similar organism), its molecular biology, rate of transmission, pathogenesis, how the human immune system responds to natural infection, and the nature of protective immunity. Economic factors may also impede vaccine development, because it requires an extensive, up-front investment in research. Most vaccine manufacturers (and policymakers) are reluctant to make the necessary financial commitment since few vaccines are highly profitable and strict federal safety and efficacy requirements make the risk of failure a very real possibility. Vaccine developers must also take into account the extra costs that may arise from liability claims for injuries or deaths blamed on vaccines. This concern has forced a number of vaccine manufacturers out of the marketplace. Industry might be encouraged to assume a greater role in vaccine development if it was asked to participate in a public/private sector collaboration, similar to NIH's National Cooperative Vaccine Development Groups, whose focus is HIV disease vaccines. Another alternative might be to offer industry various economic incentives, such as minimum guaranteed purchases, to conduct its own development work. Given the various disincentives to vaccine development for more common pathogens, the development of vaccines for emerging microbes is even more problematic. There may be potentially catastrophic consequences if the development process is left entirely to free enterprise. The committee thus believes that a comprehensive strategy is urgently needed. To bring a new vaccine rapidly from the research laboratory into general use—a necessary criterion if one hopes to prevent or control an emerging infectious disease—will require an integrated national process that defines the need for a vaccine, its technical requirements, target populations, and delivery systems; ensures the purchase and use of the developed product through purchase guarantees and targeted immunization programs; relies as much as possible on the capability of private industry to manage the vaccine development process, through the use of contracted production, if necessary; utilizes the capacity of the NIAID to manage and support basic, applied, clinical, and field research, and of the CDC and academia to conduct field evaluations and develop implementation programs; is centrally coordinated to take maximum advantage of the capabilities of the public and private sectors; and is prepared for the possible rapid emergence of novel disease threats, such as occurred in the 1918-1919 influenza pandemic. The committee recommends that the United States develop a means for generating stockpiles of selected vaccines and a "surge" capacity for vaccine

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Emerging Infections: Microbial Threats to Health in the United States development and production that could be mobilized to respond quickly to future infectious disease emergencies. Securing this capability would require development of an integrated national process, as described above. The committee offers two options for implementation of this recommendation: Develop an integrated management structure within the federal government and provide purchase guarantees, analogous to farm commodity loans, to vaccine manufacturers that are willing to develop the needed capacity. Build government-supported research and development and production facilities, analogous to the National Cancer Institute's program for cancer therapeutics and the federal space, energy, and defense laboratories. The assigned mission of these new facilities would be vaccine development for future infectious disease contingencies. ANTIMICROBIAL DRUGS The usefulness of antimicrobial drugs can be ensured only if they are used carefully and responsibly, and if new antimicrobials are continually being developed. The development of drug resistance by microorganisms, as well as the emergence of new organisms, will require replacement drugs to be in the "pipeline" even while existing drugs are still effective. The establishment of public/private sector alliances, along the lines of the National Cooperative Drug Development Groups at the NIH, may be desirable to ensure the continued development of effective antimicrobial drugs. The committee recommends that clinicians, the research and development community, and the U.S. government (Centers for Disease Control, Food and Drug Administration, U.S. Department of Agriculture, and Department of Defense) introduce measures to ensure the availability and usefulness of antimicrobials and to prevent the emergence of resistance. These measures should include the education of health care personnel, veterinarians, and users in the agricultural sector regarding the importance of rational use of antimicrobials (to preclude their unwarranted use), a peer review process to monitor the use of antimicrobials, and surveillance of newly resistant organisms. Where required, there should be a commitment to publicly financed rapid development and expedited approval of new antimicrobials. Vector Control The United States and other developed countries have been able to free themselves to a remarkable degree from the burden of vector-borne diseases

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Emerging Infections: Microbial Threats to Health in the United States by using a variety of methods of vector control. These methods include the spraying of chemical pesticides, application of biological control agents, destruction or treatment of larval development sites, and personal protection measures, such as applying repellents or sleeping under bednets. For a disease agent that is known or suspected to be transmitted by an arthropod vector, efforts to control the vector can be vital for containing or halting an outbreak. This is true even for those vector-borne diseases, such as yellow fever or malaria, for which there is or may eventually be an effective vaccine. For most vector-borne infectious diseases, the onset of winter dampens transmission; it can even, in some cases, eliminate the vector or infectious agent. The exceptions are pathogens that can survive in humans for long periods and produce chronic infection (e.g., malaria and typhus). A sudden drop in cases of an unidentified disease at the start of winter may be the first epidemiological evidence that the disease is vector borne. Although many local and regional vector-control programs can effectively combat small and even medium-size outbreaks of vector-borne disease, they are not equipped to deal with outbreaks that are national in scope. For example, regional vector-control programs cannot declare a health emergency or bypass the many legal restrictions that now limit the use of certain pesticides that are potentially useful agents for control. That authority rests with health and environmental agencies at the state and federal levels. The lack of a sufficient stockpile of effective pesticides, which might be required in the event of a major epidemic, continues to be a serious problem. The committee recommends that the Environmental Protection Agency develop and implement alternative, expedited procedures for the licensing of pesticides for use in vector-borne infectious disease emergencies. These procedures would include a means for stockpiling designated pesticides for such use. A growing problem in vector control is the diminishing supply of effective pesticides. Federal and state regulations increasingly restrict the use and supply of such chemicals, largely as a result of concerns over human health or environmental safety. In addition, the 1972 Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA; Public Law No. 92-516) requires that all pesticides used in the United States be re-registered by 1997, a procedure that requires manufacturers to submit additional safety data. Some pesticide manufacturers have chosen not to re-register their products because of the expense of gathering necessary safety data. Partly as a result, many effective pesticides developed over the past 40 years are no longer available in the United States. The Environmental Protection Agency (EPA) further restricts the use of pesticides through the Endangered Species Protection Plan, which prohibits

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Emerging Infections: Microbial Threats to Health in the United States the application of a wide range of pesticidal chemicals within the habitat of any endangered species. EPA has developed an emergency exemption procedure to allow pesticide use in restricted areas when the possibility of an outbreak of a vector-borne disease is great. This procedure, however, is extremely cumbersome and time-consuming, and the committee believes that it is essentially useless if followed as prescribed, since emergency approval of a pesticide is likely to come after the critical period during which its use could avert an outbreak. As with vaccines, there is little economic incentive for firms to develop new pesticides for public health use, primarily because such use is a very small fraction of the total pesticide market. Pesticide development is now driven mainly by the demands of agriculture. Moreover, as pesticide development has become more specialized, there are fewer compounds available that have both agricultural and public health uses. The committee feels strongly that pesticide development for public health applications needs to be given some priority. The committee recommends that additional priority and funding be afforded efforts to develop pesticides (and effective modes of application) and other measures for public health use in suppressing vector-borne infectious diseases. Public Education and Behavioral Change Public policy discussions and scientific efforts sometimes focus on vaccine and drug development to the exclusion of education and behavioral change as means for preventing and controlling outbreaks of infectious disease. This is unfortunate, because it is often only by changing patterns of human activity—from travel, personal hygiene, and food handling to sexual behavior and drug abuse—that the spread of disease can be halted. Even when scientists and public health officials rely on and encourage education and behavioral change to prevent or limit the spread of infectious disease, the public may not be convinced of its necessity. Although scientists may see emerging microbes as a very real threat to public health, the average citizen may be unaware of the potential danger or may consider those dangers to be less important than other health risks, like heart disease and cancer. In such instances, a carefully conceived media campaign may have a beneficial effect on behavior that affects disease transmission. The committee recommends that the National Institutes of Health give increased priority to research on personal and community health practices relevant to disease transmission. Attention should also be focused on developing more effective ways to use education to enhance the health-promoting behavior of diverse target groups.

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Emerging Infections: Microbial Threats to Health in the United States * * * * * It is the committee's hope that this report will be an important first step in highlighting the growing problem of emerging microbial threats to health and focus attention on ways in which the United States and the global community will attempt to address such threats, now and in the future. The committee strongly believes that the best way to prepare for the future is by developing and implementing preventive strategies that can meet the challenges offered by emerging and reemerging microbes. It is infinitely less costly, in every dimension, to attack an emerging disease at an early stage—and thus prevent its spread—than to rely on treatment to control the disease. In some instances, the measures that this report proposes will require additional funds. The committee recognizes and has wrestled with the discomforts that such recommendations can bring—for example, the awareness that there are other compelling needs that also justify (and require) increased expenditures. But policymakers and the public alike must realize and understand the potential magnitude of future epidemics in terms of human lives and monetary costs. The 1957 and 1968 influenza pandemics killed 90,000 people in the United States alone. The direct cost of medical care was estimated to be $3.4 billion (more than three times the NIAID budget for fiscal year 1992) and the total economic burden to be $26.8 billion2—almost three times the total NIH budget for fiscal year 1992. A more current example offers a similar lesson. The recent resurgence of TB (from 22,201 cases in 1985 to 26,283 cases in 1991, or 10.4 per 100,000 population), after a steady decline over the past several decades, will be costly. Every dollar spent on TB prevention and control in the United States produces an estimated $3 to $4 in savings; these savings increase dramatically when the cost of treating multidrug-resistant tuberculosis is factored in. We also have a recent example of what results when early prevention and control efforts are lacking. The costs of AIDS/HIV disease—in human lives as well as dollars—have been staggering, and the end is not yet in sight. The objective in the future should be earlier detection of such emerging diseases, coupled with a timely effort to inform the population about how to lower their risk of becoming infected. Obviously, even with unlimited funds, no guarantees can be offered that an emerging microbe will not spread disease and cause devastation. Instead, this committee cautiously advocates increased funding and proposes some more effective ways for organizations—domestic and international, public and private—as well as individuals—both health professionals and the lay public—to work together and, in some cases, combine their resources. These efforts will help to ensure that we will be better prepared to respond to emerging infectious disease threats of the future. 2   Figures are in 1992 dollars.