Submicroscopic placental infection by non-<i>falciparum Plasmodium</i> spp.

<div><p>Background</p><p>Among the <i>Plasmodium</i> species that infect humans, adverse effects of <i>P</i>. <i>falciparum</i> and <i>P</i>. <i>vivax</i> have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-<i>falciparum</i> malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy.</p><p>Methods and findings</p><p>Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for <i>Plasmodium</i> spp. Risk factors associated with <i>Plasmodium spp</i>. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes.</p><p><i>P</i>. <i>falciparum</i> was the most prevalent <i>Plasmodium</i> species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no <i>P</i>. <i>vivax</i> infections were detected in this cohort, <i>P</i>. <i>malariae</i> (9.2%) and <i>P</i>. <i>ovale</i> (5.8%) infections were observed in samples collected during the first ANV. These non-<i>falciparum</i> infections were also detected in maternal peripheral blood (1.3% for <i>P</i>. <i>malariae</i> and 1.2% for <i>P</i>. <i>ovale</i>) at delivery. Importantly, higher prevalence of <i>P</i>. <i>malariae</i> (5.5%) was observed in placental than peripheral blood while that of <i>P</i>. <i>ovale</i> was similar (1.8% in placental blood). Among the non-<i>falciparum</i> infected pregnant women with paired peripheral and placental samples, <i>P</i>. <i>malariae</i> infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of <i>P</i>. <i>malariae</i> for the placenta. However, no assoctiation of non-<i>falciparum</i> infections and the pregnancy outcomes was observed</p><p>Conclusions</p><p>Overall this study provided insights into the molecular epidemiology of <i>Plasmodium</i> spp. infection during pregnancy, indicating placental infection by non-<i>falciparum Plasmodium</i> and the lack of association of these infections with adverse pregnancy outcomes.</p>