ABSTRACT
BACKGROUND: Plasmodium falciparum can be detected by microscopy, histidine-rich-protein-2 (HRP2) capture test or PCR but the respective clinical relevance of the thereby diagnosed infections in pregnant women is not well established. METHODS: In a cross-sectional, year-round study among 839 delivering women in Agogo, Ghana, P. falciparum was screened for in both, peripheral and placental blood samples, and associations with maternal anaemia, low birth weight (LBW) and preterm delivery (PD) were analysed. RESULTS: In peripheral blood, P. falciparum was observed in 19%, 34%, and 53% by microscopy, HRP2 test, and PCR, respectively. For placental samples, these figures were 35%, 41%, and 59%. Irrespective of diagnostic tool, P. falciparum infection increased the risk of anaemia. Positive peripheral blood results of microscopy and PCR were not associated with LBW or PD. In contrast, the HRP2 test performed well in identifying women at increased risk of poor pregnancy outcome, particularly in case of a negative peripheral blood film. Adjusting for age, parity, and antenatal visits, placental HRP2 was the only marker of infection associated with LBW (adjusted odds ratio (aOR), 1.5 (95%CI, 1.0-2.2)) and, at borderline statistical significance, PD (aOR, 1.4 (1.0-2.1)) in addition to anaemia (aOR, 2.3 (1.7-3.2)). Likewise, HRP2 in peripheral blood of seemingly aparasitaemic women was associated with PD (aOR, 1.7 (1.0-2.7)) and anaemia (aOR, 2.1 (1.4-3.2)). CONCLUSION: Peripheral blood film microscopy not only underestimates placental malaria. In this highly endemic setting, it also fails to identify malaria as a cause of foetal impairment. Sub-microscopic infections detected by a HRP2 test in seemingly aparasitaemic women increase the risks of anaemia and PD. These findings indicate that the burden of malaria in pregnancy may be even larger than thought and accentuate the need for effective anti-malarial interventions in pregnancy.
Subject(s)
Malaria, Falciparum/diagnosis , Microscopy, Polarization/methods , Placenta Diseases/parasitology , Plasmodium falciparum/isolation & purification , Pregnancy Complications, Parasitic/parasitology , Animals , Antigens, Protozoan/analysis , Antimalarials/therapeutic use , Female , Ghana/epidemiology , Humans , Malaria, Falciparum/epidemiology , Malaria, Falciparum/parasitology , Malaria, Falciparum/prevention & control , Placenta Diseases/epidemiology , Placenta Diseases/prevention & control , Plasmodium falciparum/metabolism , Polymerase Chain Reaction/methods , Pregnancy , Pregnancy Complications, Parasitic/epidemiology , Pregnancy Complications, Parasitic/prevention & control , Protozoan Proteins/analysis , Pyrimethamine/therapeutic useABSTRACT
Toll-like receptors (TLRs) are involved in recognition of and response to Plasmodium falciparum. In 304 primiparous Ghanaian women, we examined whether common TLR4 and TLR9 polymorphisms influence susceptibility to and manifestation of malaria during pregnancy. The TLR variants did not affect P. falciparum prevalence or parasite density. However, in P. falciparum-infected women, both the TLR4 Asp299Gly and the TLR9 T-1486C polymorphisms increased the risk of low birth weight in term infants 6-fold, and, additionally, TLR4 Asp299Gly increased the risk of maternal anemia 5-fold; preterm delivery was not associated with these TLR variants. These findings suggest that TLR4 and TLR9 play a role in the manifestation of malaria during pregnancy.
Subject(s)
Genetic Predisposition to Disease/genetics , Malaria, Falciparum/genetics , Polymorphism, Genetic/genetics , Pregnancy Complications, Parasitic/genetics , Toll-Like Receptor 4/genetics , Toll-Like Receptor 9/genetics , Adolescent , Adult , Anemia/genetics , Female , Ghana , Humans , Infant, Low Birth Weight , Infant, Newborn , PregnancyABSTRACT
In a group of 596 delivering Ghanaian women, the sensitivities of peripheral blood thick film microscopy, ICT Malaria P.f/P.v test, and PCR in detecting microscopically confirmed placental Plasmodium falciparum infection were 42, 80, and 97%, respectively. In addition to the gross underestimation of placental malaria by peripheral blood film microscopy, submicroscopic infections were found to be a risk factor for maternal anemia.
