The competition between malaria strains
Malaria is a major problem in sub-Sharan Africa. Every year around 250 million people are infected with the parasite called Plasmodium. It is spread by mosquitoes and enters the blood stream through their bite. Children suffer most from this parasite and one in five child deaths in Africa are attributed to it.
Nearly all malaria infections are caused by several strains which infect the host at the same time. This makes the parasite’s survival difficult because it is faced with other competitive strains. Those strains fight for the host's resources.
A research group of the University of Edinburgh now have an answer to the question on how the parasite survives this battle for supplies.
To be able to hold out under these challenging conditions Plasmodium develop a strategy which alters if their victim is already infected. Instead of making cells that can be taken up by other mosquitoes so as to spread the disease, the parasite focuses on forming cells which aim to cause a quick infection. As a result, the strain has less resources left to pass on the illness. For the parasite this is a draw back in the short term because it slows down the rate of transmittance. However it is the only way to survive the rivalry in the bloodstream.
Laura Pollitt of the School of Biological Sciences, who led the study, said: “Our results explain a long-standing puzzle of parasite behaviour. We found that when parasites compete with each other, they respond with a sophisticated strategy [...]. They opt to fight it out in the bloodstream rather than risk everything on the chance of infecting mosquitoes in the short term.”
This study was published in American Naturalist and sponsored by the Wellcome Trust, the Biotechnology and Biological Sciences Research Council and the Natural Environment Research Council.