The rise and fall of the Global Malaria Eradication Program

The availability of cheap, effective long-lasting insecticides such as DDT and antimalarial drugs such as chloroquine (Bruce-Chwatt 1987, Najera et al. 2011, WHO 2008b), combined with oversimplified understanding of the ecology and epidemiology of malaria transmission systems (Garrett-Jones 1964, MacDonald 1957, Trigg and Kondrachine 1998), led to the adoption of the Global Malaria Eradication Programme (GMEP) in 1955 by the 8th World Health Assembly (WHO 1955). This campaign was based on the widespread use of DDT for indoor spraying to tackle adult mosquitoes and antimalarial drugs (chloroquine had also been established as a cost- effective option) to treat malaria and clear parasites from humans. Literally, eradication of any given pathogen refers to its complete disappearance from the globe with resulting zero incidence of infection (Greenwood 2008b, WHO 2008b). Achieving this ambitious goal for malaria depends on number of major pre-requisites including: 1) full understanding of the biology of disease vectors and parasite which often vary with epidemiological setting (Bruce-Chwatt 1987,

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Ferguson et al. 2010, Griffin et al. 2010), 2) availability of locally efficacious intervention options (Greenwood 2008a, Greenwood 2008b, Griffin et al. 2010, WHO 2008b), 3) long term commitment of both political and financial support from governments of all endemic countries and their overseas partners (Feachem and Sabot 2008, Mills et al. 2008, Sabot et al., Tanner and Savigny 2008), 4) major improvement of health systems (Abel-Smith and Rawal 1992, de Savigny and Adam 2009, McIntyre et al. 2006) and 5) broad social economic development (Sachs and Malaney 2002, Tanner and Savigny 2008).

Although GMEP was initiated with a supposedly global agenda, it excluded most of sub-Saharan Africa with the exception of Ethiopia, South Africa and Zimbabwe (Feachem and Sabot 2008, Trigg and Kondrachine 1998, WHO 2008b), even though this is where the majority of malaria burden occurs (Guerra et al. 2008, Hay et al. 2004, Hay et al. 2009, Snow et al. 2005, WHO 2009). This region was excluded because of the limited health infrastructure and implementation capacity, as well such intensive transmission that even perfect implementation might not necessarily completely eliminate it (Bruce-Chwatt 1984, Bruce-Chwatt 1987, Trigg and Kondrachine 1998, WHO 2008b). Even where malaria control programs were launched in Africa, they were mostly concentrated on urban rather than rural settings, contrary to the stated strategy of the GMEP as it was implemented elsewhere. There are a number of speculations about how this policy was formulated and it is thought that these priorities were set because urban settings harboured economically important work forces, and because urbanization is associated with greater population density and economic development, thus enabling easier implementation (Schapira and Kumar 1989).

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Malaria was successfully eliminated from most endemic developed countries, large areas of subtropical Asia and Latin America, as well as the highlands of Madagascar. At this point, it is important to distinguish between elimination and eradication: while the latter refers to global extinction of a pathogen, the more tractable former goal refers to local extinction from a specified area such as district, country, region or continent. Although the GMEP did not achieve its objective of malaria eradication, it removed the threat of malaria from over one billion people living where it was eliminated and greatly reduced the burden of malaria in many endemic countries outside Africa. However, challenged with lack of political will, limited resources and the resilient transmission systems of Africa and the pacific (Najera 2001, Najera et al. 2011, Sharma 1996, Trigg and Kondrachine 1998), it is not surprising that the programme fell far short of its local targets in many subtropical and tropical countries. The overall goal of global eradication was never achieved, and soon after the programme ended in 1967, malaria returned to areas where it had been temporarily eliminated (Bruce-Chwatt 1987, Feachem and Sabot 2008, Najera 2001, WHO 2008b). Other contributing factors to the collapse of this campaign included the increasing resistance of malaria vectors to insecticides, particularly DDT, and mosquito behavioural adaptations to avoid such pesticides (Curtis 2002, Molineaux and Gramiccia 1980, Najera et al. 2011, Soper 1965, WHO 2006a, Wyler 1983) and of malaria parasites resistance to drugs (Bruce-Chwatt 1987, Peters 1982, Soper 1965, Trigg and Kondrachine 1998). Resistance problems were attributed to the large scale use of antimalarial drugs and the overuse and misuse of DDT in agriculture, the enormous logistical challenges any program of such large scales faces, and rising costs of residual insecticides (Bruce-Chwatt 1987).

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Recognizing these challenges, the twenty-second World Health Assembly re-assessed its strategy in 1969 and concluded that complete eradication remained the ultimate goal but that achievable levels of control was a more realistic, realizable target for the foreseeable future in those areas where elimination was not immediately feasible (Bruce-Chwatt 1987, Trigg and Kondrachine 1998, WHO 1969b, WHO 2008b), emphasizing effective use of available intervention options in each specific national context (Najera et al. 2011, Trigg and Kondrachine 1998, WHO 2008b). However, it was also concluded that existing tools were not sufficient to eradicate the disease in areas of intense transmission intensity, notably sub-Saharan Africa (Griffin et al. 2010, Molineaux and Gramiccia 1980, WHO 2008b). Consequently, this led the WHO (WHO 1969a) to lower its ambitious targets and extended its timelines for eradication indefinitely by changing its policy from eradication to sustained control (Molineaux and Gramiccia 1980, Trigg and Kondrachine 1998). The resulting loss of confidence and support among donors and governments for the programme resulted in a dramatic fall in funding and the capacity of most malaria endemic countries to continue with systematic malaria control. This led to the formal termination of the GMEP, with a wholesale reduction in financial support for antimalarial programs which started with the withdrawal of the US contribution in 1963 to the WHO Malaria Special Account, which represented more than 85% of the total budget (Najera 2001, Najera et al. 2011). As the flow of financial and technical support from the international community dried up, the WHO recommended that each malaria-endemic country should commit itself to establishing antimalarial activities in accordance with its available human, technical and financial resources, and to maintain these activities until the disease no longer posed a major public health problem (WHO 2008b). In practice most developing countries suffered from economic deterioration during the 1970s (Bruce-Chwatt 1987), particularly in Africa where most

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nations struggled with newly-acquired independence, so this transition to locally-sustained programmes was not successfully realized in practice. Consequently, malaria control programmes deteriorated dramatically during economic crisis of the 1970s, leading to aggressive resurgence of the disease across the tropics (Hay et al. 2002, Romi et al. 2002, Sharma 1996, Wyler 1983).