Malaria is an infectious disease that accounts for some 300,000 deaths every year in Africa. Whilst significant efforts over the last 20 years mean that this number is around half of what it was in the year 2000, it is still the biggest single disease killer across the breadth of Africa. The main contributors to the reduced death toll have been the widespread use of insecticide treated bednets, which stop infected mosquitoes from biting people and therefore infecting them, and the better use of drugs to treat disease. It is with renewed confidence then, that the global community has articulated a grand plan to eradicate malaria by 2040.
However, there are at least two challenges to this ambitious proposal. Just as we are starting to make real gains, the parasite is beginning to fight back. The progress that has been made is in danger of being reversed because the parasite is evolving resistance to our drugs and this resistance is spreading. Therefore a crucial part of the global strategy for malaria control is to monitor the spread of antimalarial drug resistance, and identify and contain drug resistant strains when they’re found.
The second challenge relates to the changing nature of malaria transmission. As parasite prevalence drops, fewer people are infected. So malaria changes from being an endemic disease, where most people are infected most of the time, to an epidemic disease where new infections can arise in isolated groups of previously uninfected people. In such cases, it is not clear whether these new infections represent the recrudescence of local parasites or whether they are due to the importation of new parasites from elsewhere. Local malaria control strategies will differ greatly depending on which of these two scenarios best explains new infections.
Fortunately, there is an approach that can provide both up-to-date information about which drugs a parasite is resistant to and which populations it is related to: DNA sequencing. Drug resistance manifests itself as mutations in the parasite genome, and by comparing an unknown parasite genome to a reference database, we can understand where it comes from. Traditionally, genome sequencing has been expensive and lab-based, and global parasite reference datasets have been unavailable. But not any more.
Côte kwa pwani is a bold and innovative scientific expedition that will take the very latest mobile genetic sequencing technology into remote malarial regions of Africa and perform realtime genetic analysis of parasite DNA in the field. For the first time, this will allow scientists on the ground to test new malarial infections for the presence of drug resistance and to understand where they have come from. Côte kwa pwani is a collaboration between British and African scientists and a major ambition for the expedition is to raise awareness for the need for scientific training and infrastructure investment in Africa so that future African scientists can perform similar analyses to those undertaken during the expedition.