Submicroscopic malaria parasitemia and migration: the hidden weight carried by pregnant women.

IntroductionSubmicroscopic malaria parasitemia is a known phenomenon for years, however there are currently not enough existing data to set guidelines for diagnosis and treatment. Due to multiple reasons, pregnant women arrived recently from endemic areas seem to be particularly at risk of submicroscopic malaria parasitemia, which can only be diagnosed by molecular techniques. This study aims to determine the prevalence of submicroscopic malaria parasitemia in pregnant women coming from endemic areas and to pin down its potential consequences on maternal and birth outcomes. MethodsA prospective study on pregnant women that recently arrived from endemic areas for malaria was conducted in the Obstetrics Department of CHU Saint-Pierre (Brussels). Several P. falciparum detection techniques were performed for each participant on 2 maternal (pre and postnatal) and 1 cord blood samples, using both conventional tests and loop-mediated isothermal amplification (LAMP). Placentas were also analyzed to search for placental malaria. Birth outcomes were collected. Patients with and without submicroscopic malaria parasitemia were compared. ResultsMaternal and umbilical blood samples were collected in 96 enrolled patients and analyzed by conventional tests and loop mediated isothermal amplification. Among the enrolled patients, 5 (5.2%) had submicroscopic malaria parasitemia. Patients with submicroscopic malaria parasitemia had left their endemic area more recently (p <0.05), had higher reticulocyte counts in both maternal prenatal blood (p <0.02) and cord blood (p <0.02) and had higher lactate dehydrogenase level in cord blood (p <0.05). No impact of submicroscopic malaria parasitemia on birth weight and term of birth was detected. ConclusionThe prevalence of submicroscopic malaria parasitemia in pregnant women arriving in non-endemic countries is non negligible. More data need to be collected to assess the consequences of submicroscopic malaria parasitemia on maternal and birth outcomes.