Gestational malaria associated to Plasmodium vivax and Plasmodium falciparum placental mixed-infection followed by foetal loss: a case report from an unstable transmission area in Brazil

Abstract

Gestational malaria is a multi-factorial syndrome leading to poor outcomes for both the mother and foetus. Although an unusual increasing in the number of hospitalizations caused by Plasmodium vivax has been reported in Brazil, mortality is rarely observed. This is a report of a gestational malaria case that occurred in the city of Manaus (Amazonas State, Brazil) and resulted in foetal loss. The patient presented placental mixed-infection by Plasmodium vivax and Plasmodium falciparum after diagnosis by nested-PCR, however microscopic analysis failed to detect P. falciparum in the peripheral blood. Furthermore, as the patient did not receive proper treatment for P. falciparum and hospitalization occurred soon after drug treatment, it seems that P. falciparum pathology was modulated by the concurrent presence of P. vivax. Collectively, this case confirms the tropism towards the placenta by both of these species of parasites, reinforces the notion that co-existence of distinct malaria parasites interferes on diseases' outcomes, and opens discussions regarding diagnostic methods, malaria treatment during pregnancy and prenatal care for women living in unstable transmission areas of malaria, such as the Brazilian Amazon.

Figure 1

Schematic representation of the major events reported in this case. Diagnosis, treatment and symptoms are reported as they occurred in a chronological manner. Following the P. vivax positive blood smear diagnosis, the patient remained hospitalized until delivery, when placental tissue and mother's peripheral blood samples were collected and molecular analyses were performed. Two months after foetal loss, a new blood sample was collected, allowing P. falciparum molecular diagnosis by nested-PCR.

Figure 2

The presence of P. falciparum- and P. vivax-infected erythrocytes in the placenta collected after foetal loss. Agarose gel electrophoresis of nested-PCR amplified products in the presence of species-specific human malaria parasite oligonucleotides (VIV or FAL, specific for P. vivax or P. falciparum, respectively) based on the parasite small subunit ribosomal RNA (ssrRNA) gene. Both P. vivax and P. falciparum gDNA were found in the placenta; no plasmodial gDNA was detected in peripheral blood after delivery. Abbreviations are as follows: MW, molecular weight; bp, base pair; B, patient peripheral blood sample; niB, non-infected human peripheral blood; P, patient placenta sample; niP, non-infected human placenta; C-, negative control, absence of nuclear material; Pv+ and Pf+, positive controls representing amplification product of P. vivax (120 bp) and P. falciparum (200 bp) ssrRNA gene.