The War on Malaria

Art by Elizaveta Gelfreykh

Malaria is about to be totally eradicated and you will never make a career, let alone a living from it”. This was the advice given in the 1950s to the aspiring malariologist, Robert Desowitz. The first Global Eradication of Malaria Programme was launched in 1955, and yet there are still 250 million cases recorded each year.

Malaria is a potentially deadly, infectious disease transmitted to humans by mosquitoes infected with malaria parasites, with symptoms including fever, renal failure and brain damage. The first Malaria eradication programme depended on use of the insecticide DDT. DDT was sprayed on the inside of houses, killing mosquitoes when they landed on walls after feeding. But by 1969 the evolution of resistance to DDT in the mosquito left the project in disarray. Additionally, DDT was the subject of controversy in the 1970s when issues arose regarding its toxicity and carcinogenic effects on humans. The insecticide was subsequently banned for agricultural usage in many countries.

Not only have the mosquitoes fought back, so has the malaria parasite, Plasmodium, which quickly evolved resistance to some of the most effective anti-malarial drugs, such as chloroquine. In spite of these difficulties, 37 countries were declared malaria free by 1978.

However, malaria remains endemic in 109 countries, kills 780,000 people annually and slows the growth of African economies by 2% a year. Since 2000, the Gates Foundation has poured more than $1 billion into malaria research, with the hope of eradicating the disease. But are we in a scientific position to once again put eradication plans in place?

A number of new tools have become available that have altered the ways in which malaria is controlled in the last twenty years. One of these is include artemisinin, a drug that Chinese herbalists have been using to treat malaria since the 4th century. Anti-malarial drugs derived from artemisinin have filled the gap left by resistance of the parasite to chloroquine. The effectiveness of this new drug is, however, threatened by the abundance of cheaper counterfeit drugs with lower levels of the active ingredient. Low-dose drugs do not effectively eliminate the parasite from the body, allowing the survivors to pass resistance to their offspring.

Another well-known tool is insecticide treated nets, which cost around £3 each and last for four years before requiring retreatment. An estimated 350 million nets are needed for worldwide, and 200 million have been delivered to African countries to date. It is estimated that over 900,000 deaths have been averted through insecticide treated nets between 2001 and 2010.

A key research focus of the Gates Foundation is the long-sought-after malaria vaccine. Many aspects of malaria make vaccine development difficult. First, the parasite hides in our cells, making it difficult for our immune system to locate it. Second, the parasite moves rapidly through a number of life stages, each of which must be targeted by a different vaccine. Third, there are multiple strains of the parasite, such that a vaccine against one strain is likely to be ineffective against others. Despite these challenges, a vaccine known as RTS,S has been developed. A recent field study published in the New England Journal of Medicine estimated that the vaccine results in up to 50% reduction in severe disease in children. If final trials are successful the vaccine could be on the market by 2013.

Malaria elimination is considerably harder to achieve than control. An eradication programme may transfer resources from areas where malaria is most damaging, to areas where it is easiest to eliminate. To eliminate the last 10% of malaria requires significantly more effort and funding than the previous 10%. The World Health Organisation agrees that complete interruption of malaria transmission will require additional novel control tools, beyond those currently available. Furthermore, even if a disease can be locally eliminated, transmission can quickly be resurrected with the invasion of a small number of infected mosquitoes from another region.

Bill Gates has thrown a huge amount of money at this war, yet as we can see, it will not be easily won. We can only hope that modern science will provide new weapons to outflank such persistant parasites.

Elinor Godfrey is a 2nd year DPhil student at Magdalen College and in the Zoology Department.