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The high burden of 'P. vivax' infections in children contributes to the rapid acquisition of immunity to malaria

Study published in PLoS Neglected Tropical Diseases

An international research team led by Ivo Mueller from the CRESIB, research centre of ISGlobal, has found that the high number of Plasmodium vivax infection that children experience in the first five years of life contributes to the rapid acquisition of immunity to malaria caused by this parasite. This study has been published in PLoS Neglected Tropical Diseases.

When both parasite species are co-endemic, P.vivax incidence peaks in younger children compared to P. falciparum. To identify differences in the number of blood stage infections of these species and its potential link to acquisition of immunity, we have estimated the molecular force of blood-stage infection of P. vivax (molFOB, i.e. the number of genetically distinct blood-stage infections over time), and compared it to previously reported values for P. falciparum.

P. vivax molFOB was estimated by high resolution genotyping parasites in samples collected over 16 months in a cohort of 264 Papua New Guinean children living in an area highly endemic for P. falciparum and P. vivax. In this cohort, P. vivax episodes decreased three-fold over the age range of 1-4.5 years.

While the incidence of clinical P. vivax illness was strongly associated with molFOB, molFOB itself did not change with age. The incidence of P. vivax showed a faster decrease with age in children with high compared to those with low exposure.

Ivo Mueller, researcher at CRESIB, research centre of ISGlobal (Spain), and Walter and Eliza Hall Institute (Australia), concludes that "the high number of P. vivax clones that infect children in early childhood are a major contributor to the very rapid acquisition of immunity against clinical P. vivax malaria".

Reference

Koepfli C, Colborn KL, Kiniboro B, Lin E, Speed TP, Siba PM, Felger I, Mueller I. A High Force of Plasmodium vivax Blood-Stage Infection Drives the Rapid Acquisition of Immunity in Papua New Guinean Children. PLoS Negl Trop Dis. 2013 Sep 5;7(9).