Commentary:r Malaria control in the 1990s P.I. Trigg1 & A.V. Kondrachine1 In May 1955 the Eighth World Health Assembly adopted a Global Malaria Eradication Campaign based on the widespread use of DDT against mosquitos and of antimalarial drugs to treat malaria and to eliminate the parasite in humans. As a result of the Campaign, malaria was eradicated by 1967 from all developed countries where the disease was endemic and large areas of tropicalAsia and Latin America were freed from the risk of infection. The Malaria Eradication Campaign was only launched in three countries of tropicalAfrica since it was not considered feasible in the others. Despite these achievements, improvements in the malaria situation could not be maintained indefinitely by time-limited, highly prescriptive and centralized programmes. Also, vector resistance to DDT and of malaria parasites to chloroquine, a safe and affordable drug, began to affect programme activities. A Global Malaria Control Strategy was endorsed by a Ministerial Conference on Malaria Control in 1992 and confirmed by the World Health Assembly in 1993. This strategy differs considerably from the approach used in the eradication era. It is rooted in the primary health care approach and calls for flexible, decentralized programmes, based on disease rather than parasite control, using the rational and selective use of tools to combat malaria. The implementation of the Global Strategy is beginning to have an impact in several countries, such as Brazil, China, Solomon Islands, Philippines, Vanuatu, Viet Nam and Thailand. The lesson from these areas is clear: malaria is being controlled using the tools that are currently available. The challenge is now to apply these tools among vulnerable individuals and groups experiencing high levels of morbidity and mortality, particularly in sub-Saharan Africa, for which long-term investments are required. In May 1955, the Eighth World Health Assembly, meeting in Mexico, DF, adopted a Global Malaria Eradication Campaign based on the widespread regimented use of the insecticide DDT for indoor and outdoor spraying against adult mosquitos, of larvicides for treating mosquito breeding sites, and of antimalarial drugs to treat malaria and to eliminate the parasite in humans. This decision hinged on the idea that the transmission of malaria in a community would be interrupted if a sufficient number of adult mosquitos were killed before the parasite development in the vector was completed. The basis for this approach was provided by Professor George Macdonald et al., who developed a mathematical model of the epidemiology of malaria which "confirmed" that transmission could be interrupted by DDT and larvicides. In fact, such an approach had led to eradication of malaria in some countries by the end of the Second World War and, in 1954, the XIV Pan American Sanitary Conference had already adopted a plan for the eradication of the disease from the Americas. DDT had been shown to be highly effective in interrupting malaria transmission, important antimalarial organizations existed in most I Malaria Unit, Division of Control of Tropical Diseases, World Health Organization, 1211 Geneva 27, Switzerland. Requests for reprints should be sent to Dr Trigg at this address. Reprint No. 5817
malarious countries (but not in the majority of countries in sub-Saharan Africa), long-term savings were expected from time-limited eradication rather than the continued control approach that previously had been carried out, and there was concern that the vectors would become resistant to DDT if control activities were maintained for long periods. The resolution to establish the WHO Global Malaria Eradication Campaign was adopted by 46 votes in favour with only 2 against and 6 abstentions, but serious criticisms were voiced in public and particularly in private. For example, Dr J.N. Togba, Liberia, stated in Mexico that "Large-scale malaria control might present no great difficulties in a relatively well-developed country like Venezuela or an island like Ceylon, but the magnitude of the task of spraying residual insecticides in every village of Liberia, in the face of bad communication and adverse weather conditions, could hardly be imagined unless it had been experienced". "Furthermore, he therefore thought that it would be ill advised to arouse the hopes of governments and run the risk of censure when results failed to come up to expectations". He considered also that the proposed appropriation of funds "was not even a drop in the ocean" for the task ahead.a The delegates of France and the Eighth World Health Assembly, Mexico, DF, 10-22 May 1955. Resolutions, decisions, plenary meetings and annexes. Geneva, World Health Organization, 1955. a
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United Kingdom expressed great reservations on the affordability and the sustainability of the enterprise and indicated their doubts on the implied urgency. Sub-Saharan Africa was represented at the Eighth World Health Assembly by only three independent countries (Ethiopia, Liberia, and South Africa) and by the metropolitan governments of the colonial powers, Belgium, France, Portugal, Spain, and the United Kingdom. After the Assembly, even the colonial governments of Africa expressed disillusion at not having been consulted about the resolution. The Assembly also authorized the DirectorGeneral of WHO to obtain financial contributions from governments and private sources to assist countries to implement the campaign, but contributions were meagre. Between 1956 and 1963, US$ 20.33 million were donated, of which the USA contributed US$ 17.5 million (86.1%). As a result, the Global Eradication Campaign started in 1956 as a timelimited, regimented, centralized, and insufficiently funded enterprise with political overtones. The paper by Medecin-Colonel Bernard, published in 1956, reflects the concerns expressed at the World Health Assembly in 1955 and by many individuals following the initiation of the WHO Global Eradication Campaign. He pointed out that insecticide spraying had not had any impact on malaria transmission in tropical Africa and questioned the efficacy of the methods being used and whether the considerable expenditure was justified. While not ruling out the eventual eradication of malaria in this continent and even calling for a concerted action to do so, he suggested that there were other major problems apart from funding that needed to be addressed before such a campaign should be initiated in Africa. These problems included the following: the lack of personnel trained in malaria and its eradication; logistic problems related to transport difficulties particularly during the rains; the shortage of water needed to spray vast areas during the dry season; the different habits of African populations that affect malaria transmission, and without whose collaboration eradication could not be achieved; and the different biology of the vectors that would affect the impact of spraying. History was to show that these concerns were justified not only for Africa but also for most of the world where malaria was present. In the event, this international effort to eradicate malaria excluded most of sub-Saharan Africa, with the exception of Ethiopia, South Africa, and Southern Rhodesia (Zimbabwe). Vector control interventions were not considered feasible in most of this region because of the intensity of transmission and the limited health infrastructure to support such a programme. However, as a result of the Campaign, 12
malaria was eradicated by 1967 from all endemic developed countries and large areas of subtropical Asia and Latin America were freed or practically freed from the risk of infection. In India alone, morbidity and mortality was reduced to about 100000 clinical cases and 1000 deaths each year. Despite these achievements, it was realized that the objectives of global eradication could not be reached without a well-developed and publichealth-oriented infrastructure. It became obvious that improvements in the malaria situation could not be maintained indefinitely without substantial national commitments and international assistance in view of the mounting operational, financial, and technical problems faced by the programmes. In retrospect, it is easy to see that a solution was sought by oversimplification and standardization and that many programmes lacked the epidemiological and administrative expertise. These factors were overlooked because of the humanitarian appeal and urgency of the eradication effort. In addition, technical constraints such as resistance of vectors to DDT and of the parasites to chloroquine began to affect programme activities. The recognition of these constraints led the Twenty-second World Health Assembly, held in Boston, MA, in 1969, to re-examine the strategy and conclude that, while complete eradication of malaria was the ultimate goal, there were regions where eradication did not yet appear feasible and that, in such areas, its control with the means available should be encouraged as a necessary and valid step towards eventual eradication. This effectively ended the WHO Global Eradication Campaign, and an almost immediate effect was the considerable reduction in financial support to antimalarial programmes. The capabilities of malaria-endemic countries to continue their antimalarial operations were further reduced by the world economic crisis in the early 1970s that resulted in a dramatic rise in the prices of insecticides and drugs and of shipping costs. As a result of the reduction in antimalarial activities, especially vector control, and the inability of countries to formulate and implement realistic and epidemiologically sound plans for combating the disease, malaria started a gradual and sometimes even dramatic resurgence. Guarded optimism re-emerged in the 1980s. It was expected that the development of a primary health care approach to health services, as recommended by the International Conference on Primary Health Care, held in Alma-Ata, in 1978, together with a well-informed and actively participating community would ensure the necessary infrastructure for the delivery of antimalarial action. The implementation of malaria control based on the primary health WHO Bulletin OMS. Vol 76 1998
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care approach was, however, slow. This was due in part to problems in interpreting this approach, a reluctance on the part of governments to move away from practices used during the eradication era, and to delays in the further development and implementation of national health services based on the primary health care approach. Thus, the malaria problem continued to increase through the 1980s and 1990s, often in epidemic proportions, compounded by insufficient financial and human resources, changes in climate, and in land use and migration as populations strove to increase their economic potential. Problems were most severe in areas burdened with war and civil unrest, illegal trade, and mass movements of refugees. Hence, by the beginning of the 1990s, it was estimated that each year 300-500 million people were clinically ill with malaria, while 1.5-2.7 million people died from the disease. A total of 90% of these cases were in sub-Saharan Africa. Although the burden of malaria is confined to these areas of Africa, multidrug-resistant falciparum malaria that had started in the 1980s in parts of South-east Asia and South America continued to spread and threaten malaria control in other parts of the world. In view of this deteriorating situation, WHO's Executive Board proposed in 1990 that a Ministerial Conference on Malaria should be held to mobilize affected countries and the international community to intensify their malaria disease control efforts. This conference, which took place in 1992 in Amsterdam, adopted a World Declaration on the Control of Malaria and a Global Malaria Control Strategy that was consequently confirmed by the World Health Assembly in 1993, and by both the Forty-ninth Session of the United Nations General Assembly and the Thirty-third Ordinary Session of the Assembly of Heads of State and Government of the Organization of African Unity in 1994 and 1997, respectively. The objectives of the Global Strategy are to prevent mortality and reduce morbidity as well as social and economic loss due to disease through the progressive improvement and strengthening of local and national capabilities for malaria control. It has four basic technical elements: - to provide early diagnosis and prompt treatment; to plan and implement selective and sustainable preventive measures, including vector control; - to detect, contain, or prevent epidemics; and - to strengthen local capacities in basic and applied research to permit and promote the regular assessment of a country's malaria situation, in particular, the ecological, social, and economic determinants of the disease. WHO Bulletin OMS. Vol 76 1998
The strategy calls for disease- rather than parasiteoriented control programmes and the rational use of existing and future tools to combat malaria. It recognizes that malaria problems vary enormously from epidemiological, ecological, social and operational viewpoints, and that sustainable, cost-effective control must, therefore, be based on local analysis. The strategy is firmly rooted in the primary health care approach and calls for the strengthening of local and national capabilities for disease control, for community partnership and the decentralization of decision-making, for the integration of malaria control activities with related disease programmes, and for the involvement of other sectors, especially those concerned with education, agriculture, social development, and the environment. It emphasizes the vital importance of continuing research both locally and internationally, and of international teamwork in research and control. This strategy differs significantly from past approaches to malaria, especially those used in the eradication era. Implementation of the strategy depends on a change of emphasis from highly prescriptive, centralized control programmes to flexible, cost-effective and sustainable programmes adapted to local conditions and responding to local needs. Thus, the strategy aims to control malaria through a concerted approach, using various methods of intervention based on knowledge of the local epidemiology of the disease, available resources, and the ability to maintain a sustainable impact. It is developed in such a way that it is able to accommodate any new tool, provided that it is effective, affordable and the results from its use can be sustained. An Action Plan for Malaria Control that provides objectives, targets and a timetable of activities for the implementation of the Global Strategy for the period 1995-2000 has been developed by WHO with other United Nations Agencies and was adopted by the Economic and Social Council of the United Nations in 1995. Priority in this plan is given to country support, based on the development of realistic and affordable national plans of action after an assessment of needs and priorities. Training and operational research should be part of these national plans. The action plan emphasizes the integration of malaria control activities into other health delivery programmes and general health services, especially by strengthening the community's role in prevention and control. Emphasis is placed on better partnership among United Nations agencies and other organizations involved in malaria control. The plan translates research and technical developments into policy and guidelines, on which training and education materials are based. 13
P.l. Trigg & A.V. Kondrachine Priority is given to malaria-endemic countries in sub-Saharan Africa, where over 90% of the world's malaria cases occur. These countries have an urgent need for the establishment of national malaria control programmes and for the implementation of the strategy at central and district levels. The focus in these countries is on strengthening the provision of early diagnosis and prompt treatment both at health service facilities and at the community level, the management of severe and complicated diseases, the detection and management of malaria epidemics, and the development of strong community-based programmes for malaria prevention and control. In other parts of the world, priority has been given to reorienting existing malaria control programmes in line with the principles of the global strategy. This includes the strengthening of curative services at all levels of the health care system, the promotion of rational drug use, provision of health information, and the selective use of disease prevention methods, including vector control. Within these priorities, two main objectives have been set: - by the year 1997, at least 90% of countries affected by malaria should implement appropriate malaria control programmes; and - by the year 2000, malaria mortality should be reduced by at least 20% compared to the 1995 level in at least 75% of affected countries. Since the adoption of the Global Strategy, the foundations for reducing the impact of malaria have been laid. By mid-1997, 47 of the 49 countries of subSaharan Africa had completed national plans of action for malaria control with WHO's assistance. Because of limited human and financial resources, the majority of these national plans are only at the initial stages of implementation. However, US$ 10 million was allocated by WHO's Director-General for use in 1997 for accelerated implementation in 21 selected countries in the African Region and 3 African countries in the Eastern Mediterranean Region for which plans of action have been developed and are now being implemented; an additional US$ 10 million has been allocated to expand the project in 1998. By the end of 1996, over 10000 individuals were trained at the district and community levels, with priority being given to disease management. This number has increased markedly with the instigation of intensified implementation of malaria control in Africa in 1997. Outside Africa, 20 countries in the Eastern Mediterranean Region, 17 countries of the Region of the Americas, and 18 countries in the South-East Asia and Western Pacific Regions have reoriented 14
their malaria control programmes in line with the Global Strategy. Thus, globally the target that 90% of countries affected by malaria implement appropriate control programmes has been achieved. It was recognized when the Global Strategy was adopted that, although malaria was a curable disease and could be controlled by existing methods, there was no "quick fix" approach and that research would continue to be essential to provide new tools and approaches required for control as the malaria situation evolves and changes. In most areas, particularly those in sub-Saharan Africa, long-term investments are required to achieve a marked reduction in morbidity and mortality. However, implementation of malaria control according to the Global Strategy is beginning to have an impact on malaria morbidity and mortality in countries such as China, Solomon Islands, Philippines, Vanuatu, Viet Nam, Thailand, some states in India, Brazil, and Oman, as well as allowing countries in North Africa and some Middle Eastern countries to maintain their malaria-free status.
Resume La lutte antipaludique dans les annees 90 En mai 1955, la Huitieme Assemblee mondiale de la Sante, r6unie a Mexico, a d6cid6 de lancer une campagne d'6radication mondiale du paludisme fond6e sur l'utilisation a grande 6chelle du DDT pour la destruction des moustiques adultes a l'interieur et a 1'exterieur des habitations, de larvicides pour le traitement des sites de reproduction des moustiques et d'antipalud6ens pour le traitement de la maladie et l'elimination du parasite chez I'homme. La r6solution etablissant la Campagne OMS d'6radication du paludisme a e adopt6e par 46 voix contre 2 et 6 abstentions, mais des critiques serieuses ont ete formul6es en public et surtout en priv6. L'Assembl6e a aussi autoris6 le Directeur gen6ral de l'OMS a recevoir des contributions financieres gouvernementales et privees pour aider les pays a mettre en ceuvre la campagne, mais ces contributions ont ete maigres. Entre 1956 et 1963, elles se sont 6levees a US $20,33 millions, dont US $17,5 millions fournis par les Etats-Unis d'Amerique (86,1%). En consequence, la campagne, lanc6e en 1956, a pris la forme d'une op6ration limit6e dans le temps, strictement r6glementee et centralis6e, avec un financement insuffisant et des connotations politiques. Un article du m6decin-colonel Bernard, publi6 en 1956, traduisait les pr6occupations exprim6es WHO Bulletin OMS. Vol 76 1998
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par l'Assembl6e mondiale de la Sant6 de 1955 et reprises par de nombreuses voix a la suite du lancement de la campagne mondiale d'6radication. 11 faisait observer que la pulv6risation d'insecticides n'avait eu aucun impact sur la transmission du paludisme en Afrique tropicale et mettait en doute l'efficacit6 des m6thodes utilis6es en se demandant si les d6penses consid6rables engag6es dans l'op6ration 6taient justifiees. En tout etat de cause, la plus grande partie de l'Afrique subsaharienne, a 1'exception de l'Ethiopie, de I'Afrique du Sud et de la Rhod6sie du Sud (Zimbabwe) 6tait tenue a l'6cart de cette entreprise internationale d'6radication du paludisme. Les interventions antivectorielles 6taient jug6es irr6alisables dans la plus grande partie de la r6gion en raison de l'intensit6 de la transmission et de la faiblesse de l'infrastructure sanitaire sur laquelle elles auraient dO s'appuyer. Neanmoins, a la suite de la campagne, le paludisme 6tait eradiqu6 des 1967 dans tous les pays d'end6mie developpes et le risque d'infection avait pratiquement disparu dans de larges zones subtropicales d'Asie et d'Amerique latine. En Inde, par exemple, on ne comptait plus qu'environ 100000 cas cliniques et 1000 d6ces par an. En d6pit de ces succes, il est apparu que les objectifs de l'6radication mondiale ne pourraient etre atteints en I'absence d'une infrastructure bien d6veloppee et ax6e sur l'amelioration de la sant6 publique. Avec le recul, il est facile de voir que la campagne a p6che par la recherche de solutions standard qui ne tenaient pas compte de la complexit6 de la situation et que beaucoup de programmes manquaient des competences epid6miologiques et administratives necessaires. Ces facteurs ont 6t6 sous-estim6s en raison de la priorite accord6e a I'aspect humanitaire et a l'urgence du probleme. La prise de conscience de ces contraintes a conduit la Vingt et Unieme Assembl6e mondiale de la Sant6, en 1969, a reexaminer la strategie et a conclure que si 1'eradication complete 6tait le but ultime, elle n'6tait pas encore possible dans certaines regions ou il fallait privil6gier la lutte contre la maladie par tous les moyens possibles. Cela a mis fin en pratique a la Campagne OMS d'6radication mondiale, avec pour corollaire imm6diat une r6duction considerable de l'appui financier aux programmes de lutte antipaludique. Les ann6es 80 ont vu le retour a un optimisme prudent. On a alors esp6r6 que le d6veloppement des soins de sant6 primaires, dont le principe a ete 6nonc6 a Conf6rence internationale d'Alma-Ata en 1978, assurerait la mise en place de l'infrastructure necessaire a la lutte antipaludique. Toutefois, la WHO Bulletin OMS. Vol 76 1998
mise en oeuvre des moyens de lutte fond6s sur cette approche a 6te lente. En consequence, la situation s'est d6t6rior6e au point qu'au debut des ann6es 90 on estimait que 300 a 500 millions de personnes pr6sentaient chaque ann6e les sympt6mes cliniques du paludisme et que la maladie faisait 1,5 a 2,7 millions de morts, principalement en Afrique sub-saharienne, ou l'on comptait 90% du nombre total de cas. Devant cette det6rioration de la situation, une conf6rence minist6rielle sur le paludisme s'est r6unie en 1992 pour mobiliser les pays concernes et la communaut6 internationale en vue d'intensifier la lutte contre la maladie. Cette conference a adopt6 une Declaration mondiale sur la lutte antipaludique et une Strat6gie mondiale de lutte antipaludique qui ont ete confirm6es par l'Assembl6e mondiale de la Sant6 de 1993, puis par la quarante-neuvieme session de l'Assembl6e g6nerale des Nations Unies et la trente-troisieme session ordinaire de l'Assembl6e des Chefs d'Etat et de Gouvernements de l'Organisation de l'Unit6 africaine, respectivement en 1994 et 1997. La strategie mondiale a pour objectifs de prevenir la mortalite et de r6duire la morbidit6 ainsi que les pertes sociales et 6conomiques liees a la maladie, grace a la mise en place progressive et au renforcement de moyens de lutte locaux et nationaux. Elle pr6voit des programmes ax6s davantage sur la maladie que sur les parasites et vise a favoriser l'utilisation rationnelle des moyens de lutte actuels et futurs. Elle reconnait que les problemes 6pid6miologiques, ecologiques, sociaux et op6rationnels pos6s par le paludisme varient 6norm6ment, de sorte que pour etre efficaces et rentables a long terme, les moyens utilis6s doivent s'appuyer sur une analyse locale. Elle s'inspire resolument du concept des soins de sant6 primaires et s'6carte nettement des m6thodes anterieures, notamment de celles qui etaient employ6es lors de la campagne d'6radication. Sa mise en ceuvre cesse de mettre I'accent sur des programmes de lutte centralises tres normatifs au profit de solutions souples, rentables et durables, adapt6es aux conditions et aux besoins locaux. La priorit6 est accord6e aux pays d'end6mie de l'Afrique subsaharienne ou l'on recense plus de 90% du total mondial des cas de paludisme. Depuis l'adoption de la strat6gie mondiale, un systeme visant a r6duire l'impact du paludisme a commence a se mettre en place. Au milieu de 1997, 47 des 49 pays d'Afrique subsaharienne avaient 6tabli des plans d'action nationaux avec I'aide de l'OMS. Etant donn6 la faiblesse des ressources humaines et financieres disponibles, la majorite de ces plans en sont encore aux premiers stades de la 15
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mise en ceuvre. Toutefois, le Directeur g6n6ral de l'OMS a d6bloque US $10 millions en 1997 pour acc6l6rer leur application dans 21 pays de la Region africaine ainsi que dans 3 pays d'Afrique appartenant a la R6gion de la M6diterran6e orientale, pour lesquels des plans d'action ont 6te elabor6s et sont maintenant en cours d'application. Un budget supplementaire de US $10 millions a ete prevu pour 1'extension du projet en 1998. En dehors de l'Afrique, 20 pays de la Region de la M6diterran6e orientale, 17 pays de la R6gion des Am6riques et 18 pays des R6gions de I'Asie du Sud-Est et du Pacifique occidental ont r6orient6 leurs programmes pour les mettre en accord avec la strat6gie mondiale. En consequence, l'objectif pr6voyant que des programmes appropri6s de lutte
antipaludique soient appliqu6s par 90% des pays touch6s par la maladie a 6t6 atteint. Lors de I'adoption de la strategie mondiale, il a ete reconnu que si le paludisme est une maladie gu6rissable et qu'il peut etre endigue par les moyens existants, il n'existe pas pour autant de methode miracle. Neanmoins, I'application de m6thodes de lutte conformes aux principes de la strategie mondiale commence a avoir un impact sur la morbidit6 et la mortalite du paludisme dans des pays comme la Chine, les iles Salomon, les Philippines, Vanuatu, le Viet Nam, la Thaflande, certains Etats de l'Inde, le Bresil et Oman, tandis qu'elle permet a d'autres pays, comme ceux d'Afrique du Nord et certains pays du Moyen-Orient, de rester 6pargnes par la maladie.
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