ISGlobal, an institution supported by the “la Caixa” Foundation has led a multi-centre prospective study to evaluate, for the first time in different endemic regions, the burden and the impact of Plasmodium vivax infections in pregnancy. The results, published in Plos Neglected Tropical Diseases, indicate that symptomatic malaria has a negative impact on maternal health which may in turn affect the new-born’s health. The results also reveal that some areas have a high number of infected but asymptomatic women that could serve as parasite reservoir.
Out of Africa, Plamodium vivax is the predominant malaria parasite: one third of the world population is estimated to be at risk of infection. Although 90 million pregnant women are exposed to the parasite every year, little is known on the impact of P. vivax infection during pregnancy. This contrasts with the well documented evidence on the health impact of Plasmodium falciparum infection during pregnancy in sub-Saharan Africa, showing that pregnant women have an increased risk of infection and that it has negative effects on maternal and infant health.
In this study, the authors performed a multi-centre study, within the PregVax project framework, to determine the prevalence and incidence of P. vivax infection among pregnant women and to evaluate its impact on maternal and child health. The prospective study included almost 10,000 pregnant women that attended antenatal clinic visits between 2008 and 2011 in five P. vivax endemic countries: Colombia, Guatemala, Brazil, India and Papua New Guinea. The women were followed during the entire pregnancy until delivery. Parasite infection was determined by microscopy and molecular detection (parasite DNA amplification by PCR).
The results show that the overall percentage of women with infections detected by microscopy was very low (less than 2%). However, the frequency of submicroscopic infections (i.e. detectable only by PCR) was surprisingly high in some regions (up to 18% in Guatemala). The results also show that women with clinical malaria have a higher risk of anaemia, which can have a negative impact on the infants’ health.
“These results can help guide health programmes aimed at improving maternal health in endemic regions for P. vivax” says Azucena Bardají, ISGlobal researcher and first author of the study. “The results also indicate that the routine diagnosis tools are not sensitive enough to detect subclinical infections” adds Clara Menéndez, ISGlobal research professor and study coordinator. “This is particularly relevant for future malaria control and surveillance activities in countries that are on the road towards malaria elimination”, she adds.
Bardají A, Martínez-Espinosa FE, Arévalo-Herrera M. et al. Burden and impact of Plasmodium vivax in pregnancy: A multi-centre prospective observational study. PLoS Negl Trop Dis. 2017 Jun 12;11(6):e0005606.doi: 10.1371/journal.pntd.0005606