A sticky situation: the unexpected stability of malaria elimination

Malaria eradication involves eliminating malaria from every country where transmission occurs. Current theory suggests that the post-elimination challenges of remaining malaria-free by stopping transmission from imported malaria will have onerous operational and financial requirements. Although resurgent malaria has occurred in a majority of countries that tried but failed to eliminate malaria, a review of resurgence in countries that successfully eliminated finds only four such failures out of 50 successful programmes. Data documenting malaria importation and onwards transmission in these countries suggests malaria transmission potential has declined by more than 50-fold (i.e. more than 98%) since before elimination. These outcomes suggest that elimination is a surprisingly stable state. Elimination''s ‘stickiness’ must be explained either by eliminating countries starting off qualitatively different from non-eliminating countries or becoming different once elimination was achieved. Countries that successfully eliminated were wealthier and had lower baseline endemicity than those that were unsuccessful, but our analysis shows that those same variables were at best incomplete predictors of the patterns of resurgence. Stability is reinforced by the loss of immunity to disease and by the health system''s increasing capacity to control malaria transmission after elimination through routine treatment of cases with antimalarial drugs supplemented by malaria outbreak control. Human travel patterns reinforce these patterns; as malaria recedes, fewer people carry malaria from remote endemic areas to remote areas where transmission potential remains high. Establishment of an international resource with backup capacity to control large outbreaks can make elimination stickier, increase the incentives for countries to eliminate, and ensure steady progress towards global eradication. Although available evidence supports malaria elimination''s stickiness at moderate-to-low transmission in areas with well-developed health systems, it is not yet clear if such patterns will hold in all areas. The sticky endpoint changes the projected costs of maintaining elimination and makes it substantially more attractive for countries acting alone, and it makes spatially progressive elimination a sensible strategy for a malaria eradication endgame.     

Eradication of Yaws: Historical Efforts and Achieving WHO's 2020 Target

Background

Yaws, one of the 17 neglected tropical diseases (NTDs), is targeted for eradication by 2020 in resolution WHA66.12 of the World Health Assembly (2013) and the WHO roadmap on NTDs (2012). The disease frequently affects children who live in poor socioeconomic conditions. Between 1952 and 1964, WHO and the United Nations Children''s Fund (UNICEF) led a global eradication campaign using injectable benzathine penicillin. Recent developments using a single dose of oral azithromycin have renewed optimism that eradication can be achieved through a comprehensive large-scale treatment strategy. We review historical efforts to eradicate yaws and argue that this goal is now technically feasible using new tools and with the favorable environment for control of NTDs. We also summarize the work of WHO''s Department of Control of Neglected Tropical Diseases in leading the renewed eradication initiative and call on the international community to support efforts to achieve the 2020 eradication goal. The critical factor remains access to azithromycin. Excluding medicines, the financial cost of yaws eradication could be as little as US$ 100 million.

Conclusions

The development of new tools has renewed interest in eradication of yaws; with modest support, the WHO eradication target of 2020 can be achieved.     

A research agenda for malaria eradication: health systems and operational research

Health systems research and development is needed to support the global malaria eradication agenda. In this paper, we (the malERA Consultative Group on Health Systems and Operational Research) focus on the health systems needs of the elimination phase of malaria eradication and consider groupings of countries at different stages along the pathway to elimination. We examine the difference between the last attempt at eradication of malaria and more recent initiatives, and consider the changing health system challenges as countries make progress towards elimination. We review recent technological and theoretical developments related to health systems and the renewed commitment to strengthening health systems for universal access and greater equity. Finally, we identify a number of needs for research and development, including tools for analyzing and improving effective coverage and strengthening decision making and discuss the relevance of these needs at all levels of the health system from the community to the international level.     

Malaria eradication: the Taiwan experience

In November 1965, the World Health Organization (WHO) certified Taiwan as an area where malaria had been eradicated. Malaria eradication in Taiwan resulted from government initiatives and involvement, careful planning and organization, the development of basic health structure and community support, as well as the cooperation and assistance of international agencies. The Japanese colonial government of Taiwan had contributed to the antimalarial efforts through the establishment of a rudimentary health infrastructure and introduction of measures to combat malaria and other diseases during their occupation of the island from 1895 to 1945. The Chinese government regained control of the island after Japan's surrender in 1945, and with the support of the Rockefeller Foundation, established a research institute to investigate the malaria problem. Political instability in 1949, however, caused the Foundation to end its support. After the Nationalist government moved to Taiwan, it continued antimalarial efforts which received the support of WHO and other international agencies. While Taiwan followed closely WHO's guidelines and plan of attack, the development of the program illustrates the importance of local factors in shaping its actual implementation and eventual success. Malaria eradication in Taiwan went through the following phases: preparatory (1946-1951); attack (1952-1957); consolidation (1958-1964); and maintenance (after 1965).     

The malaria challenge in the 21st century: perspectives for Africa

Malaria control has had little success in Africa despite the achievements in malaria research. It is time to put more emphasis on sustainable control measures through local commitment to diagnose and treat malaria in order to prevent illness and death. This goal can be best achieved through basic health care centers, schools and safe water supplies to rural areas. Complementary actions through research and international support will be strongly needed.     

Epidemiology in the strategies for malaria control

A rapid overview is presented of the evolution of the main orientations of malaria control, since the discovery of mosquito transmission. Stated control objectives appear to have oscillated between expectations to eradicate the vector, or at least the disease, and more modest approaches to minimise the effects of the infection. High optimism was raised when a new control measure, or new combination of existing measures, appeared to be highly effective and was expected to have universal applicability. The implementation of large scale campaigns eventually found the limits of applicability of the proposed strategy and the exaggerated expectations soon gave way to disillusion and, eventually, to a revival of research. The longest and most impacting period of exaggerated expectations was the global malaria eradication campaign of the 1950s and 1960s, which completely disregarded the study of local epidemiology, considering that all it was needed was to know if an area was "malarious" or not. Research was practically abandoned and, even when reinstated after the recognised failure of the campaign, it has retained an almost exclusive orientation towards the development of control tools, drugs or eventually vaccines. One of the earliest victims of the eradication campaign was the study of epidemic malaria and its determinants in different epidemic prone areas. In spite of an extremely long period of disillusion, lasting for almost two decades, the reality of the malaria problem led WHO and member countries to agree on a global strategy of control, aiming at a realistic use of existing tools, to at least reduce or prevent mortality. An essential element of this strategy is the prevention or control of malaria epidemics and the selective use of vector control, both of which have to be based on a solid knowledge of local epidemiology, the study of which has to rejoin the path abandoned fifty years ago.     

A research agenda for malaria eradication: cross-cutting issues for eradication

Discipline-specific Malaria Eradication Research Agenda (malERA) Consultative Groups have recognized several cross-cutting issues that must be addressed to prevent repetition of some of the mistakes of past malaria elimination campaigns in future programs. Integrated research is required to develop a decision-making framework for the switch from malaria control to elimination. Similarly, a strong economic case is needed for the very long-term financial support that is essential for elimination. Another cross-cutting priority is the development of improved measures of intensity of transmission, especially at low and nonrandom levels. Because sustained malaria elimination is dependent on a functioning health system, a further key cross-cutting research question is to determine how inputs for malaria can strengthen health systems, information systems, and overall health outcomes. Implementation of elimination programs must also be accompanied by capacity building and training to allow the assessment of the impact of new combinations of interventions, new roles for different individuals, and the operational research that is needed to facilitate program expansion. Finally, because community engagement, knowledge management, communication, political, and multisectoral support are critical but poorly understood success factors for malaria elimination, integrated research into these issues is vital.     

Ten years of freedom from smallpox: lessons and experiences. Dedicated to the tenth anniversary of worldwide freedom from smallpox

Many lessons and experiences were learned during the global programme of smallpox eradication, the most important being those which could be generalized and applied to other health programmes. This does not mean imitating or implementing smallpox eradication techniques to other diseases, since each infection requires its own strategy. It is difficult to dissect out the single key element or to equate the various factors responsible for the success, as these always worked together, in combination, depending one on others. For global eradication, the element of essential importance was international cooperation and close coordination of activities between nations. This would be impossible without proper mechanisms dedicated to international cooperation in the field of health, provided by the World Health Organization, which also assured mobilization of world resources for national programmes and application of appropriate techniques across international borders. The established specific, practical and measurable goals, objectives and targets made every programme worker clearly understand what was to be accomplished and to find his own role in achieving these objectives. Operational techniques had to be flexible, modified appropriately from country to country to make them suitable to present epidemiological situations, local administrative and health structures as well as to demographic and geographic patterns. It was the effective system of surveillance and outbreak-containment that ultimately proved to have been the key to eradication. However, application of skillful management, sound epidemiological principles, advanced technology and adequate logistic support contributed significantly to the achievement of the final goal.(ABSTRACT TRUNCATED AT 250 WORDS)     

The potential contribution of mass treatment to the control of Plasmodium falciparum malaria

Mass treatment as a means to reducing P. falciparum malaria transmission was used during the first global malaria eradication campaign and is increasingly being considered for current control programmes. We used a previously developed mathematical transmission model to explore both the short and long-term impact of possible mass treatment strategies in different scenarios of endemic transmission. Mass treatment is predicted to provide a longer-term benefit in areas with lower malaria transmission, with reduced transmission levels for at least 2 years after mass treatment is ended in a scenario where the baseline slide-prevalence is 5%, compared to less than one year in a scenario with baseline slide-prevalence at 50%. However, repeated annual mass treatment at 80% coverage could achieve around 25% reduction in infectious bites in moderate-to-high transmission settings if sustained. Using vector control could reduce transmission to levels at which mass treatment has a longer-term impact. In a limited number of settings (which have isolated transmission in small populations of 1000-10,000 with low-to-medium levels of baseline transmission) we find that five closely spaced rounds of mass treatment combined with vector control could make at least temporary elimination a feasible goal. We also estimate the effects of using gametocytocidal treatments such as primaquine and of restricting treatment to parasite-positive individuals. In conclusion, mass treatment needs to be repeated or combined with other interventions for long-term impact in many endemic settings. The benefits of mass treatment need to be carefully weighed against the risks of increasing drug selection pressure.     

A research agenda to underpin malaria eradication

The interruption of malaria transmission worldwide is one of the greatest challenges for international health and development communities. The current expert view suggests that, by aggressively scaling up control with currently available tools and strategies, much greater gains could be achieved against malaria, including elimination from a number of countries and regions; however, even with maximal effort we will fall short of global eradication. The Malaria Eradication Research Agenda (malERA) complements the current research agenda--primarily directed towards reducing morbidity and mortality--with one that aims to identify key knowledge gaps and define the strategies and tools that will result in reducing the basic reproduction rate to less than 1, with the ultimate aim of eradication of the parasite from the human population. Sustained commitment from local communities, civil society, policy leaders, and the scientific community, together with a massive effort to build a strong base of researchers from the endemic areas will be critical factors in the success of this new agenda.     

Malaria: burden of disease

Despite more than 100 years since Laveran described plasmodium species and Ross confirmed that they were transmitted by female anopheline mosquitoes, malaria remains a leading cause of morbidity and mortality worldwide. Although the areas where transmission takes place have reduced, and they are by now confined to the inter tropical areas, the number of people living at risk has grown to about 3 billion, and is expected to go on increasing. Not only does malaria cause around 500 million cases every year, and between 1 and 3 million deaths, but it also carries a huge burden that impairs the economic and social development of large parts of the planet. The failed attempt to eradicate malaria gave way to the control policy that was followed by a huge resurgence of malaria during the late 70s and 80s. Together with the emergence and spread of resistance to chloroquine and the weak health infrastructure in many of the endemic countries, particularly in Africa, the malaria situation worsened worldwide. The last decade of the 20th century was witness to the international community becoming increasingly aware of the unacceptable situation that the burden of malaria represented to large parts of the world. Renewed efforts to describe the problem, design and evaluate new control strategies, design and develop new drugs, better understand the biology of the parasite and the immunity it induces in the human host, develop candidate vaccines, together with new financial support constitute renewed hope that may lead to new trends in global health.     

The United States Army and malaria control in World War II

The United States Army faced difficult malaria control problems both at home and abroad during World War II. This challenge forced the Army to develop new tools and strategies for use in malarious areas where fighting was occurring. Due to the severe malaria problems being faced in some combat areas and the need to solve these problems quickly, intensive malaria research and operational programs were developed and implemented. With these concerted efforts and the simultaneous development of new control technologies, malaria was successfully controlled in most locations. In order to accomplish this high level of control both in the US and overseas, the Army developed a very organized approach to the malaria problem and implemented it in an effective manner. The creation of new technical solutions was also strongly emphasized and out of this effort came the development of effective antimalaria drugs to replace quinine, of new insecticides and of more effective systems for delivering these insecticides. Some of the major new tools which came out of this research were DDT and drugs such as Atabrine and chloroquine. The availability of Atabrine and DDT revolutionized malaria control throughout the world. The knowledge and experience gained through the use of these new tools by the US Army and other agencies in World War II provided the basis for a new optimism regarding malaria control which then led to the development of the global malaria eradication strategy in the post-war years.     

Global eradication of lymphatic filariasis: the value of chronic disease control in parasite elimination programmes

The ultimate goal of the global programme against lymphatic filariasis is eradication through irrevocable cessation of transmission using 4 to 6 years of annual single dose mass drug administration. The costs of eradication, managerial impediments to executing national control programmes, and scientific uncertainty about transmission endpoints, are challenges to the success of this effort, especially in areas of high endemicity where financial resources are limited. We used a combined analysis of empirical community data describing the association between infection and chronic disease prevalence, mathematical modelling, and economic analyses to identify and evaluate the feasibility of setting an infection target level at which the chronic pathology attributable to lymphatic filariasis--lymphoedema of the extremities and hydroceles--becomes negligible in the face of continuing transmission as a first stage option in achieving the elimination of this parasitic disease. The results show that microfilaria prevalences below a threshold of 3.55% at a blood sampling volume of 1 ml could constitute readily achievable and sustainable targets to control lymphatic filarial disease. They also show that as a result of the high marginal cost of curing the last few individuals to achieve elimination, maximal benefits can occur at this threshold. Indeed, a key finding from our coupled economic and epidemiological analysis is that when initial uncertainty regarding eradication occurs and prospects for resolving this uncertainty over time exist, it is economically beneficial to adopt a flexible, sequential, eradication strategy based on controlling chronic disease initially.     

A research agenda for malaria eradication: modeling

Malaria modeling can inform policy and guide research for malaria elimination and eradication from local implementation to global policy. A research and development agenda for malaria modeling is proposed, to support operations and to enhance the broader eradication research agenda. Models are envisioned as an integral part of research, planning, and evaluation, and modelers should ideally be integrated into multidisciplinary teams to update the models iteratively, communicate their appropriate use, and serve the needs of other research scientists, public health specialists, and government officials. A competitive and collaborative framework will result in policy recommendations from multiple, independently derived models and model systems that share harmonized databases. As planned, modeling results will be produced in five priority areas: (1) strategic planning to determine where and when resources should be optimally allocated to achieve eradication; (2) management plans to minimize the evolution of drug and pesticide resistance; (3) impact assessments of new and needed tools to interrupt transmission; (4) technical feasibility assessments to determine appropriate combinations of tools, an associated set of target intervention coverage levels, and the expected timelines for achieving a set of goals in different socio-ecological settings and different health systems; and (5) operational feasibility assessments to weigh the economic costs, capital investments, and human resource capacities required.     

The high cost of half-hearted breastfeeding promotion in Germany

The economic value of breastfeeding to the society at large is under researched and its importance as a preventive public health strategy is underestimated. What little research there is indicates that considerable savings would accrue from following the WHO/UNICEF advice to breastfeed exclusively for six months and continue breastfeeding along with complementary foods for two years or more. Despite relatively high breastfeeding initiation in Germany, neither exclusive breastfeeding nor breastfeeding duration come close to international recommendations. Breastfeeding is mostly regarded as a woman’s personal choice and the government has been slow to engage in breastfeeding promotion, support and research. Some structures in Germany do offer support for breastfeeding women – including the growing number of Baby Friendly Hospital Initiative (BFHI) certified hospitals and a comprehensive maternity leave policy. However, the costs of breastfeeding are mostly borne by the mothers and those for breastfeeding training mostly by the individual health care workers or hospital, while the health insurance companies and society-at-large are profiting from the financial savings from exclusive and long-term breastfeeding. Factors which might improve breastfeeding rates and duration in this country include broad expansion of and financial support for both BFHI hospitals as well as training for the health care personnel who support the mother-infant dyad during the breastfeeding period.     

IPBES:生物多样性科学评估将成为政策决策的驱动因素

生物多样性和生态系统服务政府间科学-政策平台(IPBES)的目的,是为了缓解生物多样性持续减退的趋势,推动政策和科学之间的互动。2012年成立至今构建了概念模型,确定了2014—2018年的工作方案。分析IPBES工作方案的4个目的和相应交付成果可以看出,通过推出不同专题评估报告,将为全球提出生物多样性相关的新问题,给生物多样性相关的谈判和履约提出新挑战。一系列区域和全球评估报告的推出,可能通过持续积累效益,引起公众和媒体的关注,使生物多样性问题迅速政治化,形成科学驱动政策决策的趋势。应对IPBES及其生物多样性相关公约的谈判,我国需要制定深入和持续参与其国际过程的策略,需要通过培养和推荐专业水平高且政治敏感的专家,参与IPBES评估报告的具体工作,从科学层面影响评估结果,把握生物多样性领域国际政策决策动向,在保护生物多样性的基础上,维护国家利益。     

Overview of malaria control in the Americas

The malaria endemic countries of the Americas have adopted in 1992 the WHO Global Malaria Control Strategy whose difficulties of implementation have been compounded to a major reform in the health sector, as the countries adjust to conform to financial scarcity and new economic policies. Most countries of the Region have reoriented its control program from eradication of malaria to the elimination of malaria mortality and morbidity. The Region has advanced towards these objectives having already reduced its mortality by 60% and is now in the final stages of applying new tools to control transmission and rapidly advance to reduce the incidence of malaria in the Americas.     

Epidemiological considerations for malaria reduction by transmission blocking vaccination

Outside of the temperate regions, malaria transmission continues throughout much of the world in a distribution which is not very different to that of one hundred years ago. However, with the notable exception of Africa sub Sahara, the morbidity and mortality due to malaria has generally been reduced to very low levels by comparison with earlier times. In a broad sense the malaria problem today falls into two distinct compartments, 1) how to deal with the remaining problem of malaria in the affected areas outside of sub Saharan Africa and 2) how to manage the, currently, much greater problem of malaria-related morbidity and mortality in Africa sub Sahara. Malaria control campaigns of the past have always placed great emphasis on reducing malaria inoculation rates in the affected populations. This may seem entirely logical, and is, indeed, an absolute requirement where eradication of malaria from an endemic area is the goal. There can, nevertheless, be dangers as well as benefits associated with reducing malaria inoculation rates in previously endemic populations. I discuss here the epidemiological issues which should be taken into account in this respect. I then examine the role that vaccination to reduce malaria inoculation rates in endemic populations--malaria transmission blocking vaccination--could play in malaria control.