Malaria Vaccination – The prize is priceless
Malaria is a killer. Famous victims are legion, from Tutankhamun, Alexander the Great, Dante and Oliver Cromwell down to Byron and David Livingstone. We still hear today of those whose health has merely been damaged by the disease, including entertainers like Cheryl Cole and Ross Kemp. Today it kills half a million or more people a year, many of them children in sub-Saharan Africa. That is around one a minute, every minute, every hour, every day and all year. Every year.
Right up to the 19th and 20th centuries, malaria was endemic in Britain and many other parts of Europe, even in the period of the Little Ice Age (think of those Breughel paintings like Hunters in the Snow). Factors contributing to its eradication here included better housing and the lower cost of medication, together with the eradication of mosquito habitats like marshy areas. Antimalarial medicines like quinine appeared in Europe in the 16th century and synthetic substances like mepacrine and chloroquine came into use in the early 20th century.
More recently, artemisinin, found in traditional Chinese folk medicine, has been discovered to be a very effective treatment for malaria parasites that have increasingly become resistant to the existing medicines like chloroquine. For her role in this discovery, the Chinese scientist Tu Youyou shared the 2015 Nobel Prize for Physiology or Medicine.
Prevention in the first place is even more important; with over 200 million people catching malaria each year, stopping people from contracting the disease is more important than ever. While the use of insecticides and treated bed nets has been successful, finding a vaccine for malaria has long been overdue. It has been suggested that if malaria had been such an apocalyptic killer in the First World, something would have been done much sooner (as was the case with AIDS).
Can it be achieved, as it has been done with smallpox? Well, a report commissioned by the World Health Organisation has just appeared. Three years in the making and the product of 41 experts, it concludes that malaria can be eradicated by 2050. Present trends suggest the world would be largely malaria-free by then, but that a special effort will be required to rid Africa of the disease.
The bite of female mosquitoes causes malaria. They spread the Plasmodium parasite and infect areas like the blood and liver, and in some cases, the brain.
Some genes that make mosquitoes sterile or resistant to the parasite are known and one strategy being envisaged for malaria control involves producing mutant mosquitoes that are engineered to be resistant to the Plasmodium parasite. Until recently this would only apply to 50% of the offspring and would scarcely spread, but a method known as ‘gene drive’ can ensure that the mutated mosquito can pass on its resistance to virtually all its offspring and thus through a whole mosquito population.
Experiments using a gene drive to target fertility genes in female mosquitoes produced sterile females, bringing a population of caged mosquitoes down to zero within 6 months.
Of course, introducing a new scheme like this needs money. It has been estimated that a further $2 billion a year would be required, on top of the current $4.3 billion a year currently spent on malaria. Genetic modification of this kind is controversial – who should decide the regulation of this technology? In addition, getting a vaccination scheme out there is harder than just saying so. At present there are severe problems in getting the polio vaccine scheme out in Afghanistan and Pakistan. And of course, some vaccination schemes like MMR have been beset by misconceptions in recent years.
Nevertheless, this challenge is one that should be confronted. The prize is priceless.
Dr Simon Cotton, Honorary Senior Lecturer in Chemistry.