Submicroscopic Plasmodium falciparum infections in pregnancy in Ghana

Malarial parasitaemia below the threshold of microscopy but detectable by p olymerase chain reaction (PCR) assays is common in endemic regions. This st udy was conducted to examine prevalence, predictors, and effects of submicr oscopic Plasmodium falciparum infections in pregnancy. In a cross-sectional study among 530 pregnant women in Ghana, plasmodial infections were assess ed by microscopy and PCR assays. Concentrations of haemoglobin and C-reacti ve protein (CRP) were measured and antimalarial drugs (chloroquine, pyrimet hamine) in urine were demonstrated by ELISA dipsticks. By microscopy, 32% o f the women were found to harbour malaria parasites. This rate increased to 63% adding the results of the parasite-specific PCR. P. falciparum was pre sent in all but one infection. With increasing gravidity, infection rates a nd parasite densities decreased and the proportions of submicroscopic paras itaemia among infected women grew. Correspondingly, anaemia, fever and evid ence of inflammation (CRP > 0.6 mg/dl) were more frequent in primigravidae than in multigravidae. Antimalarial drugs were detected in 65% of the women and were associated with a reduced prevalence of P. falciparum infections and a raised proportion of submicroscopic parasitaemia. Both gravidity and antimalarial drug use were independent predictors of submicroscopic P. falc iparum infections. These infections caused a slight reduction of Hb levels and considerably increased serum concentrations of CRP. Conventional micros copy underestimates the actual extent of malarial infections in pregnancy i n endemic regions. Submicroscopic P. falciparum infections are frequent and may contribute to mild anaemia and inflammation in seemingly aparasitaemic pregnant women.