The World Health Organization (WHO) considers “Malaria” as one of the main enemies for global public health: the latest estimates say that every year over 400 thousand victims in the world reap, many of which are children under 5 years. But now for the World Malaria Day, there may be a breakthrough in understanding the factors that influence the infection by Plasmodium falciparum, the parasite responsible for the disease. A meta-analysis on 23 scientific studies concluded that the blood group plays a role in infection and especially in the progression towards a form of severe malaria – one that can lead to permanent damage and often even to death.
In particular, people with blood group 0 seem to have less chance of getting sick and seeing the disease progressing.
The analysis, published in the journal Blood Reviews, started from a fact: in Africa – the continent most at risk – there are many more people with group “0” than there are in Europe and the United States. For what reason? Scientists have long thought that this trait can be favored, selected by evolutionary pressure. In other words, that people with blood group 0 have some advantage that allows them to pass on character.
To test the hypothesis Abraham Degarege, PhD student in epidemiology at Florida International University (Miami, USA), together with colleagues from the University of Addis Ababa (Ethiopia), the Karolinska Institute of Stockholm (Sweden) and the Research Institute of Public Health of India, analyzed 23 scientific studies investigating the possible role of blood groups in P.falciparum infection and in the course of the disease. The meta-analysis revealed that as many as 15 of these studies showed that people with non-0 blood group ( A, B, AB ) were more likely to develop the severe form of malaria.
A search of 2015, moreover, had also considered the phenomenon of rosetting in relation to the blood type of patients. Rosetting is the term used to indicate a condition in which red blood cells infected with the malaria parasite hide from the immune system by surrounding themselves with other uninfected red blood cells, thus creating rosettes, agglomerates of erythrocytes that can block blood vessels – with all its consequences, including brain damage and death. In this study the data indicated that people with blood group 0 seemed to be protected.
The theory is that the red blood cells of people with blood group 0 possess receptors that, unlike those that characterize the other groups, are not so easily intercepted by the malaria plasmodium. Therefore the red cell rosettes that form are smaller, weaker and unstable and it is easier for the immune system to break them down and attack the infected red blood cells.
“As a result,” the authors write, “the progression of P.falciparum infection is less likely to occur in individuals with blood group 0” .
But let’s get to the point: how can this information help us fight malaria? “With a better understanding of how blood groups interact with malarial infections, we open the doors to the development of treatment options and antimalarial vaccines,“ said Degarege.
According to the researchers, in fact, it is possible that the transfusion of group 0 blood to individuals who have contracted severe malaria gives greater chances of survival.
Moreover, these evidences provide the starting point for continuing in the development of drugs capable of breaking up the rosettes or interrupting the mechanism of training.