FACT SHEET Understanding Control, Elimination, and Eradication
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The three main strategies for addressing infectious diseases are control, elimination, and eradication.1 Selection of the strategy should be based on the biologic nature and life cycle of the infectious agent, the environmental context in which the agent thrives, the social and political circumstances of those hardest hit by the disease, existing and future resources and tools that will be committed to the effort, and the level of commitment to accomplish the goal. Control Reducing infection, cases, deaths and illness due to a disease. “Acceptable” levels of disease may vary by region. Consistent, sustained prevention and treatment interventions are necessary to ensure ongoing reduction of illness.
Elimination Reducing the number of cases and new infections to zero. Efforts often focus on geographic areas in which the infectious agent is endemic. Sustained intervention measures are required to ensure that the infectious agent does not re-emerge once eliminated.
Examples: Onchocerciasis in Africa, Malaria, Tuberculosis and Diarrheal Diseases
Examples: Neonatal Tetanus, Measles, Leprosy, Poliomyelitis, Lymphatic Filariasis, Tuberculosis
Eradication Permanent worldwide elimination of an infectious agent in nature – no new infections or cases of disease – but it may exist in laboratories. Intervention is not needed after a period of time.
Extinction The specific infectious agent no longer exists in nature or in the laboratory. Examples: None – complete destruction of an infectious agent has not been undertaken
Examples: Smallpox
Conditions for Successful Elimination and Eradication of Disease2 • Biological and operational considerations
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Intervention tools must have sufficient sensitivity and specificity to counter transmission, but be simple enough to be used under field conditions.
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Elimination may be achieved in one region, but results may be limited to that geographic area.
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Interventions used to control or eliminate a disease may not be adequate for eradication.
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Eradication is more feasible when humans are the sole reservoir for the infectious agent, as in smallpox, rather than one with a more complex life cycle, such as malaria, which is transmitted via mosquitoes.
Economic considerations o
Given limited health resources, eliminating or eradicating one disease reduces available resources for other diseases; the costs and benefits need to be considered in context.
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Elimination or eradication programs need to be coordinated with other health programs – the goal is to maximize the effectiveness of both the elimination/eradication effort and comprehensive health programs.
Political considerations o
Elimination and eradication efforts may fail. Setting priorities requires technical experts, decisionmakers, scientists, and community leaders.
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Success within countries or regions can generate momentum for international support.
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Political commitment is needed at all levels; advocacy is also needed at each of these levels in order to sustain the commitment of resources from domestic and international sources.
Global Campaigns to Eradicate Malaria, Smallpox and Polio, Led by WHO and Partners Campaign
Organization and Operations •
Unsuccessful malaria campaign lasted 15 years, accounted for more than one-third of WHO's expenditures and 500 employees.
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Multiple mosquito species carry the malaria parasites – resistance can develop at the vector level and at the parasite level.
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The campaign did not effectively develop comprehensive strategies, particularly in areas with high disease prevalence.
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Regions with different demographics, geography, mosquito types and strains of parasites required different strategies.
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Programs adhered to a rigid and detailed standard manual of operations that did not allow for flexibility to meet country needs.
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The effort focused on administration and implementation of existing interventions. Research was not a priority.
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Efforts did not effectively use existing health services or gain community support.
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Health systems needed strengthening in areas with endemic malaria, such as Africa.
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Resource constraints required a small staff and low personnel and program costs.
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Tools were available and epidemiology known, but research was supported.
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Resource constraints forced the campaign to function within health service systems.
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Lessons learned from malaria eradication efforts informed the smallpox campaign.
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Broad goals and flexibility were used rather than rigid manuals of operations. Campaign could adjust from country to country.
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New technologies – jet injector, bifurcated needle, and heat-stable, single dose vaccine – were key to success.
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The program worked with community and religious leaders, teachers, and village elders.
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Surveillance was fundamental and was a quality control measure.
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Annual operational costs per child dwarf intervention costs. Two doses of vaccine cost US$ 0.20; training, social mobilization and operations to deliver vaccine cost US$ 0.80.4 Sustained in-country support is needed from ministries of finance, transportation, women's affairs and religious affairs.4 Trained volunteers can vaccinate children with the oral polio vaccine. This makes delivery easier than using an injected vaccine and reduces the costs of training. Countries in the Americas bore 80 percent of costs and were certified polio-free in 1994.4
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Polio is endemic in Afghanistan, Pakistan, India, and Nigeria.5 Efforts are complicated by poverty, poor health systems, conflict geography, and dispersed populations.4 Outbreaks occur in non-endemic countries. Support is needed from governments around the world, WHO, UNICEF, Rotary International and other organizations. Technology simplifies logistics and reduces costs – e.g., vaccine vial monitor indicates exposure to excessive heat. Innovative, country-specific strategies and political will are still needed.5
Malaria3 1955 – 1969 Global Malaria Eradication Programme
Smallpox
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1966 – 1980 Smallpox Eradication Programme
Polio 1988 – present !
Eradication target was 2000 Global Poliomyelitis Eradication Initiative
Other Key Components
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Recent Calls for Malaria Eradication All countries need to strengthen monitoring, evaluating and surveillance systems and explore regional strategies to address malaria. Global malaria eradication requires new tools (insecticides, medications and vaccines) and strengthened health systems. Until new tools are available, countries with high and stable transmission need to scale up control measures to 80 percent coverage; countries with low or unstable transmission need to focus on elimination efforts. Finally, the impact of climate change on malaria transmission is unclear – more research is needed.6 1
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Centers for Disease Control. (accessed November 13, 2007), Available from: http://www.cdc.gov/mmwR/preview/mmwrhtml/su48a7.htm. Dowdle WR. 1999. The principals of disease elimination and eradication. MMWR 48(SU01):23-7. Henderson DA. 1999. Eradication: lessons from the past. MMWR 48(SU01):16-22. Hull H, et al. 1999. Perspectives from the global poliomyelitis eradication initiative. MMWR 48(SU01):50-60. World Health Organization. 2007. The case for completing polio eradication. Available from: http://www.polioeradication.org/. McMichael A, et al. 2004.Global climate change. In: Ezzati M, et al, editors. Comparative quantification of health risks. Geneva: WHO.
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