Image by Ute Frevert
and Margaret Shear
New research suggests that infections with 2 types of malaria parasite lead to greater health risks because 1 species helps the other thrive.
Investigators sought to understand what happens when the 2 most common malaria parasites cause infection at the same time, as they are known to attack the body in different ways.
The team found the first parasite helps provide the second with more of the resources it needs to prosper.
“Immune responses are assumed to determine the outcome of interactions between parasite species, but our study clearly shows that resources can be more important,” said Sarah Reece, of the University of Edinburgh in Scotland.
“Our findings also challenge ideas that 1 species will outcompete the other, which explains why infections involving 2 parasite species can pose a greater health risk to patients.”
Dr Reece and her colleagues recounted these findings in Ecology Letters.
In humans, the malaria parasite Plasmodium falciparum infects red blood cells of all ages, while the Plasmodium vivax parasite attacks only young red blood cells.
The current study, conducted in mice with equivalent malaria parasites (P chabaudi and P yoelii), showed that the body’s response to the first infection produces more of the type of red blood cell the second parasite needs.
In response to the first infection, millions of red blood cells are destroyed. The body responds by replenishing these cells.
The fresh cells then become infected by the second type of parasite, making the infection worse.
The investigators said these results appear to explain why infections with both P falciparum and P vivax often have worse outcomes for patients than infections with a single malaria parasite.
