Dynamics of Persistent Submicroscopic and Microscopic in Pregnant Women Under Intermittent Preventive Treatment: A Study Cohort in Benin.

Background: Malaria infections in pregnancy are a major cause of maternal morbidity and neonatal mortality in sub-Saharan Africa. A high proportion of these infections are submicroscopic, which are usually asymptomatic and therefore untreated during pregnancy. Intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) aims to prevent and treat all potential infections whether submicroscopic or not. However, the resistance of parasites to SP is steadily increasing. The dynamic of microscopic and submicroscopic infections in a cohort of Beninese women throughout their pregnancy and its relation to IPTp-SP has been assessed.

Methods: As a subsample of the RECIPAL project, 130 women with at least 2 infections detected by polymerase chain reaction during their pregnancy were included. Infections were categorized as new (isolated) or persistent based on genotyping, where persistent infections had identical genotypes in all studied time points. Submicroscopic infections were defined as polymerase chain reaction-positive and thick blood smear-negative. The persistence of infections according to IPTp-SP uptake was assessed.

Results: A total of 73.1% of women (95 women of 130) had exclusively persistent infections throughout their pregnancy, whereas only 7.7% (10 of 130) had exclusively new infections. During pregnancy, the median time spent with 1 persistent infection was 7.2 weeks. A considerable proportion of these persistent infections 64.3% (72 of 113) was only submicroscopic. Approximately 20% of these persistent infections occurred despite the use of IPTp-SP.

Conclusions: Using new antimalarial combinations could contribute to limit the persistence of submicroscopic infections and their probable negative effects on the mother and the fetus.