The Biology of Plasmodium vivax

Abstract

Plasmodium vivax is the second most prevalent cause of malaria worldwide and the leading cause of malaria outside of Africa. Although infections are seldom fatal clinical disease can be debilitating and imposes significant health and economic impacts on affected populations. Estimates of transmission and prevalence intensity can be problematic because many episodes of vivax originate from hypnozoite stages in the liver that have remained dormant from previous infections by an unknown mechanism. Lack of treatment options to clear hypnozoites and the ability to infect mosquitoes before disease symptoms present represent major challenges for control and eradication of vivax malaria. Compounding these challenges is the unique biology of P. vivax and limited progress in development of experimental research tools, thereby hindering development of new drugs and vaccines. Renewed emphasis on vivax malaria research is beginning to make progress in overcoming some of these challenges.

Figure 1.

The spatial global distribution of Plasmodium vivax malaria endemicity in 2010. Mean point estimates of the age-standardized annual mean P. vivax parasite prevalence in 2- to 10-year olds within the spatial limits of stable transmission. Areas of no risk and unstable risk are also shown. Areas where Duffy negative prevalence was estimated as greater than or equal to 90% are hatched to provide additional context for the impact of P. vivax on the local population within these areas. Areas in light gray: P. vivax free; dark gray: unstable transmission; hatched marks: unstable transmission and high Duffy negative. Areas from red to light blue indicate PvPR_1-99 >7% to 0%, respectively. (From Gething et al. 2010; reprinted under the Creative Commons Attribution 3.0 Unported License.)

Figure 2.

Light microscopic images of Giemsa-stained developmental stages of Plasmodium vivax during the blood-stage asexual cycle from early to late stages (left to right, respectively).