Vector-Borne Diseases Understanding the Environmental, Human Health, and Ecological Connections: Workshop Summary (2008) / Chapter Skim
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3 Integrating Strategies to Address Vector-Borne Disease
3 Integrating Strategies to Address Vector-Borne Disease
Pages 241-296
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, offer their perspectives on issues discussed by the workshop panel on integrating strategies for vector-borne disease surveillance, diagnosis, and response. Topics included the need for, and challenges of, creating multidisciplinary teams to study and respond to vector-borne disease outbreaks; opportunities to integrate the surveillance and diagnosis of vector-borne disease with outbreak response; funding opportunities; research directions; and the training of vector biologists.
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Workshop panelist Adriana Costero, vector biology program officer for NIAID's Division of Microbiology and Infectious Diseases, describes the variety of funding mechanisms and projects supported by that agency in her contribution to this chapter. These include grants for basic studies and the initial phases of translational research, training grants, and career awards.
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Fish advocates a repositioning of the field of vector biology as a collaboration of environmental sciences and infectious disease epidemiology, supported by technologies such as remote sensing and geographic information systems. Among infectious diseases, Fish concludes, "vector-borne diseases have the greatest potential for advancing the integration of ecology and environmental science into the mainstream of infectious disease epidemiology." NEEDS AND OPPORTUNITIES TO CONTROL VECTOR-BORNE DISEASES: RESPONSES TO THE IOM MICROBIAL THREATS TO HEALTH COMMITTEE RECOMMENDATIONS Barry J
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Indeed, VBDs account for 7 of 10 neglected infectious diseases that are considered to disproportionally affect poor and marginalized populations and therefore have been targeted by the World Health Organization (WHO) Special Programme for Research and Training in Tropical Diseases (TDR)
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. Other VBDs have emerged in or trafficked to new or previously endemic areas (e.g., Lyme disease, plague, Japanese encephalitis, WNV disease, and Rift Valley fever)
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. Clearly, many of the factors listed in Table 3-2 condition the emergence of all TABLE 3-1 Factors in Emergence of Infectious Diseases • Microbial adaptation and change • Human susceptibility to infection • Climate and weather • Changing ecosystems • Economic development and land use • Human demographics and behavior • Technology and industry • International travel and commerce • Breakdown of public health measures • Poverty and social inequality • War and famine • Lack of political will • Intent to harm SOURCE: IOM (2003)
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. infectious diseases, not just VBDs.
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aegypti and yellow fever virus (YFV) were introduced into the New World on slave ships.
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should work with academia, private organizations, and foundations to support efforts at rebuilding the human resource capacity at both academic centers and public health agencies in the relevant sciences -- such as medical entomology, vector and reservoir biology and ecology, and zoonoses -- necessary to control vector-borne and zoonotic diseases. Background Erosion in the human resource capacity to address VBDs is linked to the erosion of overall public health infrastructure for VBDs.
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Indeed, it was difficult to identify local medical entomologists, vector biologists, and arbovirologists to respond to the WNV emergency in the initially affected states. There has been a reduction in the numbers of medical entomologists, vector biologists, and vector control personnel.
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Training Training of a new generation of vector biologists/medical entomologists capable of applying modern molecular and information technology approaches to prevent and control emerging and resurging VBDs is critical. A number of agencies, including WHO-TDR, PAHO, NIH, CDC, and private foundations, recognized this situation and initiated training programs for vector biologists and medical entomologists in the United States and other countries.
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These types of programs need to be continued and expanded upon in the future, especially to transfer scientific and technical know-how to the developing world where improved vector and disease control is a matter of life and death. Unfortunately, funding for the CDC FTP in Vector-Borne Infectious Diseases has been terminated after one funding cycle, despite the productivity and popularity of this program, which was such a well-conceived approach to address human resource needs in field-oriented vector biology and VBD control.
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, which TABLE 3-3 Innovative Approaches to Restoring Human Resource Capacity in Vector-Borne Diseases • stablish a medical entomology/vector biology program to complement the existing CDC EIS E program • stablish RCEs in medical entomology/vector biology, preferably incorporated into larger E interdisciplinary comprehensive infectious disease centers • ew training initiatives (e.g., Biology of Disease Vectors course) for targeted areas for N training new leaders and advancing the field scientifically • argeted RFAs for field-oriented research using modern molecular and quantitative tools and T approaches • ong-term sustainable laboratories in disease-endemic countries for training, research, and L surveillance of VBDs SOURCE: Adapted from IOM (2003)
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The development of safe and effective pesticides and repellents, as well as novel strategies for prolonging the use of existing pesticides by mitigating the evolution of resistance, is paramount in the absence of vaccines to prevent most VBDs. In addition, newer methods of vector control -- such as biopesticides and biocontrol agents to augment chemical pesticides, and novel strategies for interrupting vector-borne pathogen transmission -- should be developed and evaluated for effectiveness.
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was founded to address this and other needs and opportunities identified in the 2003 IOM report. The major objectives of the IVCC are to partner with industry to develop new pesticides and formulations and to develop new tools and approaches to manage vector control programs and mitigate pesticide resistance, focusing upon vector control in and around the house.
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The IVCC is partnering with industry to develop and deploy new public health pesticides and/or formulations for vector control. The cost of developing a new insecticide is in the range of $70 million.
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, and for developing new pesticides for vector control. New biopesticides and biocontrol agents to augment chemical pesticides The Committee also recommended renewed effort in developing a new generation of biocontrol agents, such as viruses and bacteria, which could augment chemical pesticides and be incorporated into IPM approaches for vector control.
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; new insight into the vector immune system and the development of the field of vector immunology (Christophides et al., 2002; Bartholomay et al., 2003; Keene et al., 2004; Blandin et al., 2004; Waterhouse et al., 2007) ; new immunization strategies that incorporate vector salivary protein antigens to reduce pathogen transmission or other antigens for vector killing vaccines (e.g., Titus and Ribiero, 1988; Kamhawi et al., 2000)
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Summary The renaissance in vector biology is providing unprecedented information concerning the molecular basis of vector biology and critical vector phenotypes that could be exploited for vector control. Testimony to the growth of the field from the black box of the vector to the renaissance in vector molecular biology is the formation of VectorBase (Lawson et al., 2007)
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, or risk of pathogen exposure (presence or abundance of infected vectors or vertebrates, presence or incidence of human disease) have been developed for a variety of diseases including hantavirus pulmonary syndrome, Lyme disease, plague, and WNV disease in the United States, and dengue and malaria in tropical areas (e.g., Kitron et al., 1991; Glass et al., 1995, 2000, 2002; Boone et al., 2000; Hay et al., 2000; Brownstein et al., 2002; Rogers et al., 2002; Peterson et al., 2005; Diuk-Wasser et al., 2006; Eisen et al., 2006, 2007a,b)
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. In the case of GIS-derived risk models for vector-borne and zoonotic diseases based on epidemiological data in the United States, plague and hantavirus pulmonary syndrome models are most reliable because probable sites of pathogen exposure are determined through comprehensive case investigations carried out by state health agencies or CDC (Eisen et al., 2007a,b)
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Support was provided by the Innovative Vector Control See http://www.ent.iastate.edu/medent.
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CDC subject matter experts in epidemiology, medical entomology, vertebrate ecology, virology, immunology, pathology, diagnostics, human behavior, public communication, and so forth readily work as teams to address specific outbreak events and to formulate comprehensive approaches to further public health programs. In addition, CDC frequently works closely with a variety of government, academic, and Research Entomologist; Chief of the Arboviral Diseases Branch, Division of Vector-Borne Infectious Diseases.
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Because vector-borne zoonotic diseases involve nonhuman components (e.g., mosquitoes and birds amplify West Nile virus) , monitoring enzootic/epizootic transmission activity may provide early warning of conditions that result in epidemic transmission.
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An example of such a program is the still experimental ArboNET/plague surveillance system. 10 This system, a partnership between the CDC Division of Vector-Borne Infectious Diseases and the NASA Science Mission Directorate, Earth-Sun System Division Applied Sciences Program, is designed to evaluate and verify models as early warning tools for plague.
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As a result, vector control is the primary strategy for disease prevention and pesticides are integral to pest management programs designed to manage vector populations. Pesticides to control mosquitoes target larvae with a variety of modes of action (e.g., insect growth regulators, oils, microbial-produced insecticides like Bacillus thuringiensis israelensis or B
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While it is laudable that many of these jurisdictions have chosen to add such staff to deal with the problems stemming from the West Nile virus introduction, in my experience many of the positions are being filled by entomologists lacking public health training or experience. Many are highly skilled, professional entomologists, but many come from fields like insect ecology, forest entomology, or crop entomology and are responding to changes in the current job market.
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12 The findings and conclusions in this report are those of the author and do not necessarily represent the views of the U.S. Department of Agriculture, Animal and Plant Health Insepction Service, Veterinary Services, Centers for Epidemiology and Animal Health (CEAH)
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However, West Nile virus outbreaks have exposed weaknesses in communication and coordination between human public health and animal health agencies, as described in a Government Accountability Office (GAO) 2000 report: Links between public and animal health agencies are becoming more important.
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APHIS's operational program units mobilized to participate in multidisciplinary teams include Animal Care, Biotechnology Regulatory Services, International Services and Trade Support Team, Plant Protection and Quarantine, Wildlife Services, and Veterinary Services. Each team contributes its vast experience, knowledge, and expertise to collaborative responses.
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The outbreak of West Nile virus is an example of the need to integrate the varied animal, human, and entomological surveillance and laboratory systems. By monitoring an outbreak and anticipating the potential transmis
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Effective historical and ongoing links between vector-borne disease and the broader public health agenda have involved public health, animal health, and entomology experts, such as in the cases of equine encephalitides, West Nile virus, and Rift Valley fever. HHS, CDC, DHS, and APHIS have identified many agents and diseases that could be used for bioterrorism, many of which are zoonotic.
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vectors in Kenya • "Remotely sensed satellite climate and environmental data to detect elevated populations of mosquito vectors of emerging arboviruses in the U.S.," to develop an early warning system to detect elevated populations of potential vectors of RVF and other mosquito-borne emerging virus threat in the United States, providing decision support for agricultural and public health officials to implement improved agricultural and medical planning for potential containment and control operations • "Vector competence of North American mosquitoes for Rift Valley fever," to assess and determine epidemiological and entomological factors to facilitate/ develop effective RVFV control measures • "Countermeasures to control and eradicate RVF," through diagnostics Addressing questions through a multidisciplinary systems approach, including predictive modeling, is an essential component of the research that is needed. Research related to prevention and control measures, as well as effective vaccines for viral diseases in both humans and animals, is also needed.
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. The idea that once having emerged, such vector-borne diseases would settle down and become endemic background problems has, in the past 50 years, been shattered by tens of millions of deaths from increasingly drug-resistant falciparum malaria, by a 30-fold increase in the incidence of dengue associated with the emergence and global spread of dengue hemorrhagic fever, and by the emergences and reemergences of many other important vector-borne diseases, such as Lyme disease, West Nile virus disease, Rift Valley fever, and others (Gubler, 1998)
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For example, yellow fever, dengue, and chikungunya are largely urban diseases; the first emergence of West Nile virus in the western hemisphere occurred in New York City; and the resurgence of tick-borne encephalitis in the former Soviet Union has been fueled by the building of dachas in periurban fringes of large cities, placing millions of urbanites in direct contact with rural microorganisms (Morens et al., 2004)
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In the past decade, for example, the genes of all three "players" in the global tragedy of falciparum malaria have been fully sequenced -- the parasite, the vector Anopheles gambiae, and the human host -- and that information is now beginning to be exploited in search of new disease-fighting tools. Thus, there is hope that with an additional emphasis on translational and applied research, seemingly insurmountable problems of vector-borne diseases can be met with new solutions.
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When West Nile virus was imported into the United States in 1999, it was learned that some states had abandoned their vector control capacities entirely. Some states had no vector control personnel at all.
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Models for funding national and international vector control were never fully established and are now largely forgotten or no longer relevant. Aedes aegypti and malaria eradication programs are remembered only by senior experts, most of them retired.
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With the exception of a few excellent schools, prominent among them the London School of Hygiene and Tropical Medicine, and the Johns Hopkins School of Public Health, public health schools seem incapable of making substantial contributions to the creation of a professional and scientific workforce engaged in interdisciplinary approaches to vector-borne diseases in their current configurations. Beyond schools of public health, the picture remains grim.
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Two approaches that have worked extremely well, as judged by the quality and output of scientific work and the record of professional development of vector-borne disease and tropical medicine researchers, have been those of the U.S. Department of Defense (DoD)
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The flow of biological materials, the life blood of vector-borne disease research, is now impeded, and often times stopped entirely, by air transport regulations (International Air Transport Association [IATA] and Air Transport Association [ATA]
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By 1899, the London School of Hygiene and Tropical Medicine had been set up, followed by an explosion of public health and tropical disease research in the United States.
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It would probably be a mistake to try to recreate these golden days of tropical medicine by returning to the formulae that worked then. The problem of vector-borne diseases is a complex one that goes beyond simple "bug and drug" solutions.
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Research on a variety of vectors and their associated pathogens is supported by different funding mechanisms. Grant applications in the Vector Biology portfolio come in mostly as unsolicited grants, and occasionally in response to NIAID 21 Vector Biology Program Officer, Division of Microbiology and Infectious Diseases.
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have allowed for the development of short-term vector control technologies and approaches. Conference grants support new investigators in their participation in scientific meetings.
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Some DMID initiatives, such as the International Research in Infectious Diseases (IRID) Program, and the Tropical Medicine Research Centers (TMRCs)
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for differentiation and identification of Aedes aegypti subspecies and populations. American Journal of Tropical Medicine and Hygiene 47(6)
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Emerging Infectious Diseases 13(8) :e1, http://0-www.cdc.gov.mill1.sjlibrary.
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2006. Modeling the spatial distribu tion of mosquito vectors for West Nile virus in Connecticut, USA.
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Emerging Infectious Diseases 6(3)
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Emerging Infectious Diseases 11(8)
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1999. Origin of the West Nile virus responsible for an outbreak of encephalitis in the northeastern United States.
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Emerging Infectious Diseases 9(1)
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2002. The emer gence of West Nile virus in North America: ecology, epidemiology, and surveillance.
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INTEGRATING STRATEGIES TO ADDRESS VECTOR-BORNE DISEASE 295 WHO (World Health Organization)
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