Children with a hereditary blood disorder called alpha thalassemia produce red blood cells of a smaller size which generally cause mild anemia. A group of scientists has discovered that this disease has a benefit: it can protect children against malaria. Their findings are gathered in a study published in the latest volume of PLoS Medicine.
“Having a lower quantity of hemoglobin in a larger number of red blood cells is an advantage against malaria", explained Karen Day, from the department of Medical Parasitology of the New York University (United States), who led the investigation carried out in collaboration with the University of Oxford.
This study shows how children with mild types of alpha thalassemia are protected all their lives against the threat of the anemia produced by malaria. Moreover, it poses a response to a biological puzzle which appeared for the first time 50 years ago.
Close to 800 children from Papua New Guinea were included in the study. Malaria is endemic in this region and 68% of the children who live there have alpha thalassemia.
Day’s team showed that a severe attack of malaria results in the loss of between one third and one half of the body’s red blood cells, which number around a trillion (1,000,000,000,000) per liter of blood. Children with alpha thalassemia tolerate this massive loss because they have between 10 and 20 per cent more red blood cells than children without this condition - adaptation.
"Children with alpha thalassemia adapt to the loss of red blood cells associated with malaria by producing more of this type of cell, although they contain a lower amount of hemoglobin than usual", stated Day. "In this way, the children with alpha thalassemia are protected because they have a higher total amount of hemoglobin when they suffer from a malaria attack in comparison with normal children".