Maternal-Fetal Conflict During Infection: Lessons From a Mouse Model of Placental Malaria

Imported severe Plasmodium falciparum infection in the first trimester of pregnancy complicated by post-artemisinin delayed hemolysis and intrauterine fetal death, a case report

BACKGROUND

Post-artemisinin delayed hemolysis (PADH) is a serious complication in patients who recover from severe malaria after receiving artemisinin-based combined therapy (ACT), including artemether-lumefantrine. In Japan, among the antimalarial drugs recommended by the World Health Organization (WHO) guideline for severe malaria, intravenous quinine gluconate is available only in 29 designated hospitals, and intravenous artesunate is unavailable. Therefore, oral artemether-lumefantrine is occasionally administered as an alternative, even though it may be a suboptimal treatment. In non-endemic settings like Japan, a lack of knowledge of malaria and the side effects, such as post-artemisinin delayed hemolysis caused by the ACT, can have critical consequences. Like our patient, being a primigravida in the early stages of pregnancy is a serious risk factor for severe malaria and must be carefully monitored.

CASE PRESENTATION

This report describes a severe case of imported Plasmodium falciparum malaria complicated by fetal loss and prolonged anemia, requiring frequent blood transfusions. The patient was a previously healthy pregnant Japanese female in her 30 s. She developed a high fever 2 days after returning from Nigeria. The patient fulfilled the severe malaria criteria by WHO. On arrival, an abdominal ultrasound incidentally revealed a fetus of 5 week gestational age with a heartbeat in the uterus. Given her pregnancy and the severity of the disease, she was administered intravenous quinine 16 mg/kg as a loading dose. However, the second dose of quinine was not administered due to frequent vomiting and QTc prolongation. We initiated treatment with oral artemether-lumefantrine, and clearance of parasitemia was confirmed by microscopic observation on day 4. Miscarriage was noted on day 6 after admission. Moreover, the patient became feverish again up to 39 °C, and from days 14 to 22, the patient required multiple blood transfusions due to PADH. On day 40, follow-up was discontinued as the hemoglobin level exceeded 10 g/dL.

CONCLUSIONS

In patients who recover from severe malaria after ACT treatment, monitoring the hemoglobin level for at least a month is strongly recommended for prompt identification of PADH. Travelers to malaria-endemic countries, especially primigravida women, should be provided with adequate information on the risk and prevention of infection.

Prevalence of Malaria and Associated Factors among Delivering Mothers in Northwest Ethiopia

Background

Malaria is one of the leading causes of morbidity and mortality especially in pregnant women and under-five-year-old children. However, data on the prevalence among delivering mothers, potential fetal transmission, and associated birth outcomes is lacking in Ethiopia.

Objective

To assess the prevalence of Plasmodium infection from peripheral, placental, and cord blood samples among delivering mothers in Kuch health center, Northwest Ethiopia.

Methods

An institution-based cross-sectional study was conducted among 218 delivering mothers from February to May 2021 in Kuch health center. Data on sociodemographic characteristics and clinical and obstetric history of mothers were collected using a structured questionnaire. Giemsa stained blood films from maternal capillary and placental and umbilical cord blood were examined for plasmodium infection. Data were analyzed using Statistical Package for the Social Sciences version 23 software package.

Results

The prevalence of maternal, placental, and umbilical cord malaria was 6.4% (14/218), 2.3% (5/218), and 0.5% (1/218), respectively. Plasmodium falciparum and Plasmodium vivax accounted 3.7% (8/218) and 2.8% (6/218), respectively, in maternal peripheral blood but only Plasmodium falciparum was detected in placental and umbilical cord blood samples. Maternal malaria had significant association with primigravida (χ² = 12.611, p = 0.002) and low birth weight (χ² = 8.381, p = 0.004). Placental malaria was also significantly associated with low birth weight (χ² = 32.255, p ≤ 0.001).

Conclusion

The prevalence of malaria among delivering mothers was considerable. Maternal peripheral malaria had a significant association with gravidity and birth weight. Placental and umbilical cord malaria also had a significant association with birth weight. Pregnant mothers should be examined for malaria and receive appropriate treatment to prevent adverse birth outcomes.

TLR4-Endothelin Axis Controls Syncytiotrophoblast Motility and Confers Fetal Protection in Placental Malaria

Pregnancy-associated malaria is often associated with adverse pregnancy outcomes. Placental circulatory impairments are an intriguing and unsolved component of malaria pathophysiology. Here, we uncovered a Toll-like receptor 4 (TLR4)-TRIF-endothelin axis that controls trophoblast motility and is linked to fetal protection during Plasmodium infection. In a cohort of 401 pregnancies from northern Brazil, we found that infection during pregnancy reduced expression of endothelin receptor B in syncytiotrophoblasts, while endothelin expression was only affected during acute infection. We further show that quantitative expression of placental endothelin and endothelin receptor B proteins are differentially controlled by maternal and fetal TLR4 alleles. Using murine malaria models, we identified placental autonomous responses to malaria infection mediated by fetally encoded TLR4 that not only controlled placental endothelin gene expression but also correlated with fetal viability protection. In vitro assays showed that control of endothelin expression in fetal syncytiotrophoblasts exposed to Plasmodium-infected erythrocytes was dependent on TLR4 via the TRIF pathway but not MyD88 signaling. Time-lapse microscopy in syncytiotrophoblast primary cultures and cell invasion assays demonstrated that ablation of TLR4 or endothelin receptor blockade abrogates trophoblast collective motility and cell migration responses to infected erythrocytes. These results cohesively substantiate the hypothesis that fetal innate immune sensing, namely, the TRL4-TRIF pathway, exerts a fetal protective role during malaria infection by mediating syncytiotrophoblast vasoregulatory responses that counteract placental insufficiency.

Intravital imaging of host-parasite interactions in organs of the thoracic and abdominopelvic cavities

Infections with protozoan and helminthic parasites affect multiple organs in the mammalian host. Imaging pathogens in their natural environment takes a more holistic view on biomedical aspects of parasitic infections. Here, we focus on selected organs of the thoracic and abdominopelvic cavities most commonly affected by parasites. Parasitic infections of these organs are often associated with severe medical complications or have health implications beyond the infected individual. Intravital imaging has provided a more dynamic picture of the host-parasite interplay and contributed not only to our understanding of the various disease pathologies, but has also provided fundamental insight into the biology of the parasites.

Key Infections in the Placenta

Congenital infections are an important cause of morbidity and mortality worldwide, especially in low-income settings. This review discusses the main pathways of infections and associated adverse maternal and fetal outcomes, considering the TORCH pathogens, including Zika virus; the acronym stands for Toxoplasma gondii infection, other (Listeria monocytogenes, Treponema pallidum, and parvovirus B19, among others, including Zika virus), rubella virus, cytomegalovirus, and herpes simplex viruses type 1 and type 2.