Immature Gametocytes of the Malaria Parasite Hide in Bone Marrow

Gametocytes, which are immature sexual stages of the malaria parasite that play a crucial role in malaria transmission, hide in bone marrow. This is the conclusion of a study led by researchers from CRESIB (Barcelona Centre for International Health Research), an ISGlobal research centre, and just published in Blood. The study, reports evidence of a high prevalence and abundance of early sexual stages of Plasmodium falciparum in bone marrow compared with peripheral blood. 

ISGlobal researchers, led by Ruth Aguilar and Alfredo Mayor, used polymerase chain reaction (PCR) to quantify P falciparum gametocytes at different stages of maturation in bone marrow and peripheral blood of anaemic children from Mozambique. Their aim was to determine the presence and abundance of early, intermediate and mature stages of the parasite in blood and bone marrow samples. To date, only a few small studies using microscopy have reported the presence of immature gametocytes in bone marrow. The CRESIB study is the first ex vivo study to use PCR, which is a much more sensitive technique than microscopy, to quantify P falciparum sexual stages in children exposed to but not necessarily infected with malaria. The molecular study showed a high prevalence of the sexual phase of the parasite in the study population as well as high levels of immature stages of the gametocyte in the bone marrow compared with peripheral blood. As Ruth Aguilar explained, "we also showed a relationship between blood disturbances and gametocyte development in bone marrow."

The results indicate that virtually all anaemic children with P falciparum infection are gametocyte carriers that can potentially contribute to malaria transmission. "The fact that microscopy fails to detect a high proportion of gametocytes and that anaemic children may be an important reservoir of the malaria parasite should be taken into account when designing control measures to interrupt malaria transmission," concluded Aguilar.

More information

Aguilar R, Magallon-Tejada A, Achtman AH, Moraleda C, Joice R, Cisteró P, Li WaiSuen CS, Nhabomba A, Macete E, Mueller I, Marti M, Alonso PL, Menéndez C, Schofield L, Mayor A. Molecular evidence for the localization of Plasmodium falciparum immature gametocytes in the bone marrow. Blood. 2013 Dec 13. [Epub ahead of print]