The presence of the malaria parasite 'P. vivax' in the bone marrow affects red blood cell production

A study codirected by Hernando A. del Portillo, ICREA researcher at ISGlobal and IGTP, and Marcus Lacerda, from Brazil, reveals the presence of different stages of Plasmodium vivax in the bone marrow of a patient during the acute phase of the infection and shows that this may alter the production of red blood cells (erythropoiesis). The results, published in Plos Neglected Tropical Diseases, place the bone marrow as a potential site for the production, maturation or sequestering of gametocytes, the transmissible form of the parasite. This phenomenon had already been described for P. falciparum by several researchers, including a team from ISGlobal. 

P. vivax is the most widely distributed malaria parasite across the world. Its presence in bone marrow of infected individuals was described in the 19th century, but little was known on the stages infecting the tissue or on its biological relevance.  In this study, the authors performed a morphological and molecular analysis of bone marrow aspirates obtained from a patient diagnosed with P. vivax infection, at the FMT-HVD Hospital of Manaos. Samples were taken before and after treatment completion and were compared with blood samples from the same individual.  

The authors found that P. vivax gametocytes were enriched in the bone marrow as compared to peripheral blood, and that the earlier phase of the parasite (the one that infects humans) was also present. Morphological analysis of the bone marrow revealed signs of inefficient and abnormal erythropoiesis. In addition, molecular profiling of erythrocyte precursors, performed in collaboration with IGTP researchers, revealed changes in the expression of genes involved in red blood cell differentiation.   

“This study quantifies for the first time the different parasite stages present in the bone marrow and suggests that the parasite can infect and mature in this tissue”, says Hernando A. del Portillo. “The next step”, he adds, “is to determine whether the bone marrow can act as a gametocyte reservoir, which would contribute to disease transmission”.   

The Barcelona Institute for Global Health is supported by the “la Caixa” Foundation and a WHO Collaborating Centre for Malaria Control, Elimination and Eradication. 

Reference:

Baro B, Deroost K, Raiol T, et al. Plasmodium vivax gametocytes in the bone marrow of an acute malaria patient and changes in the erythroid miRNA profile. PLoS Negl Trop Dis. 2017 Apr 6;11(4):e0005365.