Wednesday, 26 June 2013

Malaria eradication: is it possible? Is it worth it? Should we do it?

The malaria map is rapidly shrinking. In 1900, endemic malaria was present in almost every country. Nowadays, the disease has been eliminated in 111 countries and 34 countries are advancing towards elimination.1 Elimination is defined as the absence of transmission in a defined geography—typically a country.2 Successful malaria control programmes in the remaining 64 countries with ongoing transmission have helped to reduce global incidence by 17% and mortality by 26% since 2000.3 For the 34 eliminating countries, the reductions were 85% in incidence and 87% in mortality.1 This progress is encouraging, but is worldwide eradication of human malaria possible? If so, is it a worthwhile goal and should we commit to it?
Is eradication possible? Probably yes; however, substantial challenges exist. First, despite progress, the burden of malaria is still great and it is widespread. In 2010, an estimated 219 million cases of malaria were reported and 660 000 people died in 98 countries.3 Second, drug and insecticide resistance are on the rise. In Burma, Cambodia, China, Thailand, and Vietnam, resistance of Plasmodium falciparum, the major human malarial parasite species, to artemisinin, the most widely used first-line drug, has been detected and could be spreading despite efforts to contain it.34 Resistance to pyrethroid insecticides can happen quickly and has emerged after large-scale distributions of bednets in several regions.5 Although new drugs and insecticides are being sought, none are expected to be available in the near future. Third, increased mobility of people not only makes containment of resistance difficult, but also threatens the introduction or reintroduction of malaria parasites to receptive areas. Fourth, outside sub-Saharan Africa, Plasmodium vivax, the second major human malarial parasite species, is the main challenge. P vivax is much less researched than is P falciparum. P vivax is harder to diagnose and failure to successfully treat its dormant liver stage results in relapses that can fuel onward transmission. Furthermore, in Borneo and neighbouring regions, evidence now exists of human infection by a monkey parasite species, Plasmodium knowlesi. Zoonotic reservoirs challenge all campaigns for eradication of human infection. Fifth, extreme events, such as wars or natural disasters, greatly disrupt malaria control and elimination activities, and can lead to substantial resurgence. When accompanied by large population movements, these events can introduce malaria into previously malaria-free areas. Sixth, as malaria becomes rare, persuasion of governments to allocate finances to maintain effective elimination or post-elimination programmes is increasingly difficult. Since 1930, 75 resurgences of malaria have been recorded and nearly all are linked to the scaling back of programmes.6These six factors present notable challenges on the road to eradication. However, all have potential solutions resulting from substantial international collaborative efforts that range from basic research to improvements in policy and financing arrangements.............

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