Since 2000, malaria deaths around the world have fallen by nearly half. The steepest drop has come in sub-Saharan Africa, where 90% of fatalities occur. Malaria still kills around 450,000 people each year – most of them children in Africa. The World Health Organization (WHO) estimates that better control prevented the deaths of 3.9m African children between 2001 and 2013.
In the first half of the 20th century malaria killed 2 million people a year. Controlling malaria has required not just money but persistence and political will. Elimination would save millions of lives and trillions of dollars in lost productivity and health costs, mostly in poor countries. A global eradication effort begun in 1955 dramatically decreased malaria deaths over the following decade. But the disease came back as the eradication-effort weakened and the mosquitos became more resistant.
Some 40 species of Anopheles mosquito, found all over the world, act as hosts for the types of malaria that affect humans. The parasites travel to the liver, where they multiply rapidly. They then infect red blood cells and continue to proliferate. Flu-like symptoms begin when the parasites break out of the blood cells, one to four weeks after the bite. Other mosquitoes can then pick up the parasite when they bite an infected person and pass it on when they bite another one.
Five types of malaria cause illness in humans. Plasmodium falciparum is responsible for the vast majority of deaths, having killed virtually all of the 528,000 people who died from malaria in sub-Saharan Africa in 2013. Plasmodium vivax is the most geographically widespread variety, responsible for most cases of malaria outside sub-Saharan Africa. Eradication efforts focus on these two more virulent species.
Tackling the Plasmodium parasite and its insect hosts has proven equally difficult. Both are skilled at developing resistance to drugs or insecticides; and resistant strains tend to spread fast. Resistance works the other way, too. People who live in endemic areas become partially immune to the parasite as a result of repeated infections. Symptoms are most severe among children under five, since they have not developed the resistance, and become less serious as immunity builds over time, almost disappearing in some adults.
In many parts of Africa mosquitoes are rapidly developing resistance to the four insecticides that are used to treat bed nets and spray houses. Bed nets treated with insecticide are among the more effective and widespread low-cost measures. Most countries distribute them free.
Around $2.7 billion was spent on control and elimination in 2013. The largest single source is the Global Fund to Fight AIDS, TB and Malaria. Between 2002 and 2013 the Global Fund spent $8 billion battling malaria. Despite the steep price tag, the pay-off is far bigger: the Gates Foundation puts the total economic benefits of eradication from productivity gains and health savings in the same time period at more than $2 trillion.
After decades of near misses, a vaccine is almost available. However, in the mean-time, better mapping could also help to track infections among mobile populations, who carry the malaria parasite across borders. Swaziland’s eradicators are busiest straight after Christmas, when the Mozambicans who work on the country’s sugar plantations return from visits across the border. Half Swaziland’s malaria cases are now imported. In South-East Asia malaria spreads through areas with high shares of migrant workers. Systems to track it across borders are not yet in place. However, there are some success stories. Swaziland is on the verge of becoming the first malaria-free country in sub-Saharan Africa. If it succeeds, Swaziland will join more than 100 countries that have eliminated malaria within their borders.
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