SubmicroscopicPlasmodium falciparuminfections during pregnancy, in an area of Sudan with a low intensity of malaria transmission

Abstract

There are few published studies on the burden of malaria during pregnancy from areas of sub-Saharan Africa where the intensity of malarial transmission is low, and few on submicroscopic malarial infections in pregnant women. The present study was conducted in New Halfa, an area of low-intensity transmission in eastern Sudan, between August 2003 and July 2004. The main aims were to assess the prevalences of submicroscopic and multiple Plasmodium falciparum infections in pregnant women (using the P. falciparum merozoite surface protein-2 as a polymorphic marker in PCR-based assays) and to determine the effects of such infections on anaemia during pregnancy. Of the 142 pregnant women who were recruited, only 17 (11.9%) were found smear-positive for P. falciparum by microscopy. The results of the PCR-based assays revealed, however, that 40 (32%) of the 125 smear-negative women had submicroscopic P. falciparum infections. Blood samples from 32 (80%) of those with submicroscopic infections showed only the FC 27 allele (of merozoite surface protein-2), six (15%) showed only the ICI allele, and two (5%) showed both of these alleles. Although the age, parity, gestational age and haemoglobin concentrations of the women with submicroscopic P. falciparum infections were not significantly different from those of the women who were smear- and PCR-negative, such infections may have a significant impact on materno-foetal health.

Diagnosis of Plasmoduim falciparum malaria in pregnancy in sub-Saharan Africa: the challenges and public health implications

“…One outstanding advantage of PCR is its usefulness in assessing whether discordant results are parasite-positive or parasitenegative, distinguishing true false-positive from apparent false-positive result. Moreover, PCR-based detection methods show that at least twice as many pregnant women are infected with malaria as indicated by microscopy (Mockenhaupt et al 2000;Adam et al 2005;Malhotra et al 2005;Walker-Abbey et al 2005;Mockenhaupt et al 2006;Adegnika et al 2006). Thus, a large number of pregnant women harbor submicroscopic infections, i.e., parasite DNA is detected in their blood, but parasites are not seen on blood smears (Walker-Abbey et al 2005).…”

Detection and clinical manifestation of placental malaria in southern Ghana

“…Infections detected beyond that exclusively by PCR had no discernible effect on pregnancy outcome but were still associated with reduced maternal Hb. Previous studies on that topic produced conflicting results: in Ghana but not in Sudan, Mozambique, and Cameroon, sub-microscopic peripheral blood infections as detected by PCR were associated with low Hb levels or anaemia [10,13,15,16]. Similar to the findings of the present study, P. falciparum as identified by peripheral blood microscopy or PCR in Burkina Faso was not associated with LBW or birth weight whereas the latter was reduced in case of a positive peripheral blood HRP2 dipstick [14].…”

Immune responses during gestational malaria: a review of the current knowledge and future trend of research

“…Health authorities remain to address this problem, particularly for endemic settings where most diagnosis is performed in the field. The situation has been reported in moderate and highly endemic regions [42,[131][132][133]. In the reports available, submicroscopic infection by P. falciparum is common.…”