Meta-analysis of the prevalence of malaria associated with pregnancy in Colombia 2000-2020

Knowledge about malaria associated with pregnancy is scarce in Latin America, and in Colombia, little is known about the magnitude of this infection. A systematic review was conducted to determine the prevalence of malaria associated with pregnancy (MAP) and each of its three forms: gestational (GM), placental (PM), and congenital (CM) tested using thick blood smear (TBS) and PCR. Also to compare the proportion of cases due to Plasmodium falciparum and Plasmodium vivax in Colombia from the year 2000-2020. We searched in Pubmed, Science Direct, EMBASE, EMCare, Cochrane Library, Scielo, Lilacs, Google Scholar, libraries, and repositories of Colombian universities, to obtain data on prevalence of GM, PM and CM with their respective testing method. We performed a meta-analysis with a random-effects model to obtain pooled prevalence of MAP and its three forms categorized by testing methods (TBS and PCR). We used data from 14 studies (out of 258 screened) contributing 7932, 2506 women for GM and PM respectively, also data on 1143 umbilical cord blood samples, and 899 peripheral blood of neonates. We found prevalence by TBS as, MAP 4.5% (95%CI = 2.9-6.9), GM 5.8% (95%CI = 3.8-8.7), PM 3.4% (95%CI = 1.7-6.7) and CM 1.3% (95%CI = 0.6-3.0). With PCR the prevalence was, MAP 14.4% (95%CI = 7.6-25.5), GM 16.7% (95%CI = 9.0-28.8), PM 11.0% (95%CI = 4.1-26.3) and CM 16.2% (95%CI = 8.2-29.5). The prevalence of submicroscopic infection was 8.5% (95%CI = 3.4-19.7) in GM, 10.1% (95%CI = 3.5-25.5) in PM and 22.0% (95%CI = 13.2-34.3) in CM. Infections by P. vivax was dominant over P. falciparum when tested with TBS, the PCR test gave similar proportions of P. falciparum and P. vivax. This meta-analysis has demonstrated high prevalence of MAP in Colombia, and highlights the urgent need to increase attention of researchers, research funding institutions, government agencies, and health authorities to study and intervene MAP, that has currently been under investigated.

Effects of intestinal parasite infection on hematological profiles of pregnant women attending antenatal care at Debre Markos Referral Hospital, Northwest Ethiopia: Institution based prospective cohort study

BACKGROUND

Intestinal parasitosis is a common disease that causes misery and disability in poor populations. The number of individuals affected is staggering. From two billion peoples who harbor parasites worldwide, 300 million suffer severe morbidity and more than 25% of pregnant women are infected with hookworm, which causes intestinal bleeding and blood loss, and has been most commonly associated with anemia. Intestinal parasite infection during pregnancy has been associated with iron deficiency, maternal anemia, and impaired nutritional status, as well as decreased infant birth weight.

OBJECTIVE

This study aimed to assess the effects of intestinal parasite infection on hematological profiles of pregnant women attending antenatal care in Debre Markos Referral Hospital from December 2017 to February 2019.

METHOD

A prospective cohort study design was conducted among 94 intestinal parasite-infected pregnant women as an exposed group and 187 pregnant women free from intestinal parasite were used as a control group. The effect of intestinal parasites on hematological profiles of pregnant women was assessed at Debre Markos Referral Hospital antenatal care ward. Socio-demographic data and nutrition status were assessed by using structured questionnaires and mid-upper arm circumference (MUAC), respectively. Two ml of venous blood and 2 gm of stool samples were collected to analyze the hematological profiles and detect intestinal parasites, respectively. Wet mount and formol-ether concentration (FEC) techniques were used to detect intestinal parasites. Hematological profile was analyzed using Mind ray BC-3000 plus instrument. Data were double entered into EpiData version 3.1 software and exported to SPSS version 24 software for analysis. Results were presented using tables and graphs. Associations of hemoglobin levels with intestinal parasitic infections were determined using binary logistic regression models. P≤0.05 was considered statistically significant. The mean hematological profile difference between parasite-infected and parasite-free pregnant women was computed using independent t-test.

RESULTS

In the present study, the predominant parasites identified were Entamoeba histolytica, hookworm, Giardia lamblia, Schistosoma mansoni, and Ascaris lumbricoides. About 8.2% of intestinal parasite-infected pregnant women had mild anemia while 4% had moderate anemia. Only 1.2% of intestinal parasite-free pregnant women developed moderate anemia. The mean HGB, HCT, MCV, MCH, and MCHC values of intestinal parasite-infected pregnant women were 12.8g/dl, 38.2%, 94.7fl, 33.1pg and 34.7g/dl, respectively. But the mean HGB, HCT, MCV, MCH and MCHC values of pregnant women who were free from intestinal parasites were 14.4 g/dl, 39.8%, 94.9fl, 33.9pg and 35.5g/dl, respectively. Anemia was strongly associated with hookworm (AOR = 21.29, 95%CI: 8.28-54.75, P<0.001), S.mansoni (AOR = 63.73, 95% CI: 19.15-212, P<0.001) and A.lumbricoide (AOR = 14.12, 95% CI 3.28-60.65, P<0.001).

CONCLUSION

Intestinal parasitic infection in pregnant women caused adverse impact on hematological profiles and was an independent predictor of anemia. Intestinal parasitic infection significantly decreased pregnant the level of HGB, HCT, MCV, MCH, and MCHC values. To minimize maternal anemia deworming could be good before pregnancy.

Innate immune responses to malaria-infected erythrocytes in pregnant women: Effects of gravidity, malaria infection, and geographic location

BACKGROUND

Malaria in pregnancy causes maternal, fetal and neonatal morbidity and mortality, and maternal innate immune responses are implicated in pathogenesis of these complications. The effects of malaria exposure and obstetric and demographic factors on the early maternal immune response are poorly understood.

METHODS

Peripheral blood mononuclear cell responses to Plasmodium falciparum-infected erythrocytes and phytohemagglutinin were compared between pregnant women from Papua New Guinea (malaria-exposed) with and without current malaria infection and from Australia (unexposed). Elicited levels of inflammatory cytokines at 48 h and 24 h (interferon γ, IFN-γ only) and the cellular sources of IFN-γ were analysed.

RESULTS

Among Papua New Guinean women, microscopic malaria at enrolment did not alter peripheral blood mononuclear cell responses. Compared to samples from Australia, cells from Papua New Guinean women secreted more inflammatory cytokines tumor necrosis factor-α, interleukin 1β, interleukin 6 and IFN-γ; p<0.001 for all assays, and more natural killer cells produced IFN-γ in response to infected erythrocytes and phytohemagglutinin. In both populations, cytokine responses were not affected by gravidity, except that in the Papua New Guinean cohort multigravid women had higher IFN-γ secretion at 24 h (p = 0.029) and an increased proportion of IFN-γ+ Vδ2 γδ T cells (p = 0.003). Cytokine levels elicited by a pregnancy malaria-specific CSA binding parasite line, CS2, were broadly similar to those elicited by CD36-binding line P6A1.

CONCLUSIONS

Geographic location and, to some extent, gravidity influence maternal innate immunity to malaria.

Parasitic infections during pregnancy need not affect infant antibody responses to early vaccination against Streptococcus pneumoniae, diphtheria, or Haemophilus influenzae type B

BACKGROUND

Globally, vaccine-preventable diseases remain a significant cause of early childhood mortality despite concerted efforts to improve vaccine coverage. One reason for impaired protection may be the influence of prenatal exposure to parasitic antigens on the developing immune system. Prior research had shown a decrease in infant vaccine response after in utero parasite exposure among a maternal cohort without aggressive preventive treatment. This study investigated the effect of maternal parasitic infections on infant vaccination in a more recent setting of active anti-parasitic therapy.

METHODOLOGY/PRINCIPAL FINDINGS

From 2013-2015, 576 Kenyan women were tested in pregnancy for malaria, soil-transmitted helminths, filaria, and S. haematobium, with both acute and prophylactic antiparasitic therapies given. After birth, 567 infants received 10-valent S. pneumoniae conjugate vaccine and pentavalent vaccine for hepatitis B, pertussis, tetanus, H. influenzae type B (Hib) and C. diphtheriae toxoid (Dp-t) at 6, 10, and 14 weeks. Infant serum samples from birth, 10 and 14 weeks, and every six months until age three years, were analyzed using a multiplex bead assay to quantify IgG for Hib, Dp-t, and the ten pneumococcal serotypes. Antenatal parasitic prevalence was high; 461 women (80%) had at least one and 252 (43.6%) had two or more infections during their pregnancy, with the most common being malaria (44.6%), S. haematobium (43.9%), and hookworm (29.2%). Mixed models comparing influence of infection on antibody concentration revealed no effect of prenatal infection status for most vaccine outcomes. Prevalences of protective antibody concentrations after vaccination were similar among the prenatal exposure groups.

CONCLUSIONS/SIGNIFICANCE

These findings are in contrast with results from our prior cohort study performed when preventive anti-parasite treatment was less frequently given. The results suggest that the treatment of maternal infections in pregnancy may be able to moderate the previously observed effect of antenatal maternal infections on infant vaccine responses.

IFNGR1 signaling is associated with adverse pregnancy outcomes during infection with malaria parasites

Complicated/severe cases of placental pathology due to Plasmodium falciparum and P. vivax, especially adverse pregnancy outcomes during P. vivax infection, have been increasing in recent years. However, the pathogenesis of placental pathology during severe malaria is poorly understood, while responses against IFN-γ are thought to be associated with adverse pregnancy outcomes. In the present study, we explored the role of IFN-γ receptor 1 (IFNGR1) signaling in placental pathology during severe malaria using luciferase-expressing rodent malaria parasites, P. berghei NK65 (PbNK65L). We detected luciferase activities in the lung, spleen, adipose tissue, and placenta in pregnant mice, suggesting that infected erythrocytes could accumulate in various organs during infection. Importantly, we found that fetal mortality in IFNGR1-deficient mice infected with PbNK65L parasites was much less than in infected wild type (WT) mice. Placental pathology was also improved in IFNGR1-deficient mice. In contrast, bioluminescence imaging showed that parasite accumulation in the placentas of IFNGR1-deficient pregnant mice was comparable to that in WT mice infected with PbNK65L. These findings suggest that IFNGR1 signaling plays a pivotal role in placental pathology and subsequent adverse pregnancy outcomes during severe malaria. Our findings may increase our understanding of how disease aggravation occurs during malaria during pregnancy.

Burden and impact of Plasmodium vivax in pregnancy: A multi-centre prospective observational study

Background

Despite that over 90 million pregnancies are at risk of Plasmodium vivax infection annually, little is known about the epidemiology and impact of the infection in pregnancy.

Methodology and principal findings

We undertook a health facility-based prospective observational study in pregnant women from Guatemala (GT), Colombia (CO), Brazil (BR), India (IN) and Papua New Guinea PNG). Malaria and anemia were determined during pregnancy and fetal outcomes assessed at delivery. A total of 9388 women were enrolled at antennal care (ANC), of whom 53% (4957) were followed until delivery. Prevalence of P. vivax monoinfection in maternal blood at delivery was 0.4% (20/4461) by microscopy [GT 0.1%, CO 0.5%, BR 0.1%, IN 0.2%, PNG 1.2%] and 7% (104/1488) by PCR. P. falciparum monoinfection was found in 0.5% (22/4463) of women by microscopy [GT 0%, CO 0.5%, BR 0%, IN 0%, PNG 2%]. P. vivax infection was observed in 0.4% (14/3725) of placentas examined by microscopy and in 3.7% (19/508) by PCR. P. vivax in newborn blood was detected in 0.02% (1/4302) of samples examined by microscopy [in cord blood; 0.05% (2/4040) by microscopy, and 2.6% (13/497) by PCR]. Clinical P. vivax infection was associated with increased risk of maternal anemia (Odds Ratio-OR, 5.48, [95% CI 1.83–16.41]; p = 0.009), while submicroscopic vivax infection was not associated with increased risk of moderate-severe anemia (Hb<8g/dL) (OR, 1.16, [95% CI 0.52–2.59]; p = 0.717), or low birth weight (<2500g) (OR, 0.52, [95% CI, 0.23–1.16]; p = 0.110).

Conclusions

In this multicenter study, the prevalence of P. vivax infection in pregnancy by microscopy was overall low across all endemic study sites; however, molecular methods revealed a significant number of submicroscopic infections. Clinical vivax infection in pregnancy was associated with maternal anemia, which may be deleterious for infant’s health. These results may help to guide maternal health programs in settings where vivax malaria is endemic; they also highlight the need of addressing a vulnerable population such as pregnant women while embracing malaria elimination in endemic countries.

More than 90 million pregnancies are exposed to P. vivax infection every year. While it is well known that pregnant women have an increased risk of P. falciparum infection and disease, much less is known on the epidemiology and the impact of P. vivax in pregnancy. A health-facility based observational study was conducted in pregnant women living in five vivax endemic countries aimed to determine the burden of the infection in pregnancy and its impact on the mother and the newborn health. We found that the prevalence of P. vivax malaria in pregnant women attending the routine antenatal clinic visits was overall low across all sites, however submicroscopic infections were unexpectedly high in some areas. Pregnant women with clinical malaria experienced an increased risk of anemia, which may have a deleterious impact on infant health. These findings may be useful for guiding maternal health programs in vivax endemic settings, as well as for malaria elimination activities.

Improvement of a tissue maceration technique for the determination of placental involvement in schistosomiasis

Schistosomiasis in pregnancy may cause low birth weight, prematurity and stillbirth of the offspring. The placenta of pregnant women might be involved when schistosome ova are trapped in placental tissue. Standard histopathological methods only allow the examination of a limited amount of placental tissue and are therefore not sufficiently sensitive. Thus, placental schistosomiasis remains underdiagnosed and its role in contributing to schistosomiasis-associated pregnancy outcomes remains unclear. Here we investigated an advanced maceration method in order to recover a maximum number of schistosome ova from the placenta. We examined the effect of different potassium hydroxide (KOH) concentrations and different tissue fixatives with respect to maceration success and egg morphology. Placental tissue was kept either in 0.9% saline, 5% formalin or 70% ethanol and was macerated together with Schistosoma mansoni infested mouse livers and KOH 4% or 10%, respectively. We found that placenta maceration using 4% KOH at 37°C for 24 h was the most effective method: placental tissue was completely digested, egg morphology was well preserved and alkaline concentration was the lowest. Ethanol proved to be the best fixative for this method. Here we propose an improved maceration technique in terms of sensitivity, safety and required skills, which may enable its wider use also in endemic areas. This technique may contribute to clarifying the role of placental involvement in pregnant women with schistosomiasis.

Schistosomiasis in pregnant women is associated with prematurity, low birth weight and stillbirth of the fetus. Schistosome eggs may be trapped in the placental tissue and, thus, contribute to fetal harm. As the placenta is a large organ, current microscopic histopathological examinations commonly lack sensitivity. The yield of schistosome eggs can be increased by the use of tissue maceration. However, the applied maceration procedures are labor intensive, time-consuming and cumbersome. To develop an improved maceration technique in terms of sensitivity, safety and required skills which enable its wider use in endemic areas we examined the effect of different potassium hydroxide (KOH) concentrations and different tissue fixatives with respect to maceration success and egg morphology. Placenta maceration using 4% KOH at 37°C for 24 h was the most effective method: placental tissue was completely digested, egg morphology was well preserved and alkaline concentration was the lowest. This improved technique may contribute to clarify the role of placental involvement in pregnant women with schistosomiasis.

Vertical transmission and fetal damage in animal models of congenital toxoplasmosis: A systematic review

In humans, the probability of congenital infection and fetal damage due to Toxoplasma gondii is dependent on the gestation period at which primary infection occurs. Many animal models have been used for vaccine, drug testing, or studies on host or parasite factors that affect transmission or fetal pathology, but few works have directly tested fetal infection and damage rates along gestation. So, the purpose of this work was to perform a systematic review of the literature to determine if there is a model which reflects these changes as they occur in humans. We looked for papers appearing between 1970 and 2014 in major databases like Medline and Scopus, as well as gray literature. From almost 11,000 citations obtained, only 49 papers fulfilled the criteria of having data of all independent variables and at least one dependent datum for control (untreated) groups. Some interesting findings could be extracted. For example, pigs seem resistant and sheep susceptible to congenital infection. Also, oocysts cause more congenitally infected offspring than tissue cysts, bradyzoites or tachyzoites. In spite of these interesting findings, very few results on vertical transmission or fetal damage rates were similar to those described for humans and only for one of the gestation thirds, not all. Moreover, in most designs tissue cysts - with unknown number of bradyzoites - were used, so actual dose could not be established. The meta-analysis could not be performed, mainly because of great heterogeneity in experimental conditions. Nevertheless, results gathered suggest that a model could be designed to represent the increase in vertical transmission and decrease in fetal damage found in humans under natural conditions.

Infants' Peripheral Blood Lymphocyte Composition Reflects Both Maternal and Post-Natal Infection with Plasmodium falciparum

Maternal parasitoses modulate fetal immune development, manifesting as altered cellular immunological activity in cord blood that may be linked to enhanced susceptibility to infections in early life. Plasmodium falciparum typifies such infections, with distinct placental infection-related changes in cord blood exemplified by expanded populations of parasite antigen-specific regulatory T cells. Here we addressed whether such early-onset cellular immunological alterations persist through infancy. Specifically, in order to assess the potential impacts of P. falciparum infections either during pregnancy or during infancy, we quantified lymphocyte subsets in cord blood and in infants' peripheral blood during the first year of life. The principal age-related changes observed, independent of infection status, concerned decreases in the frequencies of CD4⁺, NK^dim and NKT cells, whilst CD8⁺, Treg and Teff cells' frequencies increased from birth to 12 months of age. P. falciparum infections present at delivery, but not those earlier in gestation, were associated with increased frequencies of Treg and CD8⁺ T cells but fewer CD4⁺ and NKT cells during infancy, thus accentuating the observed age-related patterns. Overall, P. falciparum infections arising during infancy were associated with a reversal of the trends associated with maternal infection i.e. with more CD4⁺ cells, with fewer Treg and CD8⁺ cells. We conclude that maternal P. falciparum infection at delivery has significant and, in some cases, year-long effects on the composition of infants' peripheral blood lymphocyte populations. Those effects are superimposed on separate and independent age- as well as infant infection-related alterations that, respectively, either match or run counter to them.

Parasite accumulation in placenta of non-immune baboons during Plasmodium knowlesi infection

BACKGROUND

Placental malaria (PM) causes adverse pregnancy outcomes in the mother and her foetus. It is difficult to study PM directly in humans due to ethical challenges. This study set out to bridge this gap by determining the outcome of PM in non-immune baboons in order to develop a non-human primate model for the disease.

METHODS

Ten pregnant baboons were acquired late in their third trimester (day 150) and randomly grouped as seven infected and three non-infected. Another group of four nulligravidae (non-pregnant) infected was also included in the analysis of clinical outcome. Malaria infection was intravenously initiated by Plasmodium knowlesi blood-stage parasites through the femoral vein on 160(th) day of gestation (for pregnant baboons). Peripheral smear, placental smear, haematological samples, and histological samples were collected during the study period. Median values of clinical and haematological changes were analysed using Kruskal-Wallis and Dunn's Multiple Comparison Test. Parasitaemia profiles were analysed using Mann Whitney U test. A Spearman's rank correlation was run to determine the relationship between the different variables of severity scores. Probability values of P <0.05 were considered significant.

RESULTS

Levels of white blood cells increased significantly in pregnant infected (34%) than in nulligravidae infected baboons (8%). Placental parasitaemia levels was on average 19-fold higher than peripheral parasitaemia in the same animal. Infiltration of parasitized erythrocytes and inflammatory cells were also observed in baboon placenta. Malaria parasite score increased with increase in total placental damage score (rs = 0.7650, P <0.05) and inflammatory score (rs = 0.8590, P <0.05). Although the sample size was small, absence of parasitized erythrocytes in cord blood and foetal placental region suggested lack of congenital malaria in non-immune baboons.

CONCLUSION

This study has demonstrated accumulation of parasitized red blood cells and infiltration of inflammatory cells in the placental intravillous space (IVS) of baboons that are non-immune to malaria. This is a key feature of placental falciparum malaria in humans. This presents the baboon as a new model for the characterization of malaria during pregnancy.

Timing of malaria infection during pregnancy has characteristic maternal, infant and placental outcomes

We conducted a clinical study of pregnant women in Blantyre, Malawi to determine the effect of the timing of malaria infection during pregnancy on maternal, infant and placental outcomes. Women were enrolled in their first or second trimester of their first or second pregnancy and followed every four weeks until delivery. Three doses of sulfadoxine-pyrimethamine were given for intermittent preventive treatment for malaria, and all episodes of parasitemia were treated according to the national guidelines. Placentas were collected at delivery and examined for malaria parasites and pigment by histology. Pregnant women had 0.6 episodes of malaria per person year of follow up. Almost all episodes of malaria were detected at enrollment and malaria infection during the follow up period was rare. Malaria and anemia at the first antenatal visit were independently associated with an increased risk of placental malaria detected at delivery. When all episodes of malaria were treated with effective antimalarial medication, only peripheral malaria infection at the time of delivery was associated with adverse maternal and infant outcomes. One quarter of the analyzed placentas had evidence of malaria infection. Placental histology was 78% sensitive and 89% specific for peripheral malaria infection during pregnancy. This study suggests that in this setting of high antifolate drug resistance, three doses of sulfadoxine-pyrimethamine maintain some efficacy in suppressing microscopically detectable parasitemia, although placental infection remains frequent. Even in this urban setting, a large proportion of women have malaria infection at the time of their first antenatal care visit. Interventions to control malaria early and aggressive case detection are required to limit the detrimental effects of pregnancy-associated malaria.

VAR2CSA signatures of high Plasmodium falciparum parasitemia in the placenta

Plasmodium falciparum infected erythrocytes (IE) accumulate in the placenta through the interaction between Duffy-binding like (DBL) domains of parasite-encoded ligand VAR2CSA and chondroitin sulphate-A (CSA) receptor. Polymorphisms in these domains, including DBL2X and DBL3X, may affect their antigenicity or CSA-binding affinity, eventually increasing parasitemia and its adverse effects on pregnancy outcomes. A total of 373 DBL2X and 328 DBL3X sequences were obtained from transcripts of 20 placental isolates infecting Mozambican women, resulting in 176 DBL2X and 191 DBL3X unique sequences at the protein level. Sequence alignments were divided in segments containing combinations of correlated polymorphisms and the association of segment sequences with placental parasite density was tested using Bonferroni corrected regression models, taking into consideration the weight of each sequence in the infection. Three DBL2X and three DBL3X segments contained signatures of high parasite density (P<0.003) that were highly prevalent in the parasite population (49-91%). Identified regions included a flexible loop that contributes to DBL3X-CSA interaction and two DBL3X motifs with evidence of positive natural selection. Limited antibody responses against signatures of high parasite density among malaria-exposed pregnant women could not explain the increased placental parasitemia. These results suggest that a higher binding efficiency to CSA rather than reduced antigenicity might provide a biological advantage to parasites with high parasite density signatures in VAR2CSA. Sequences contributing to high parasitemia may be critical for the functional characterization of VAR2CSA and the development of tools against placental malaria.

Histopathologies, immunolocalization, and a glycan binding screen provide insights into Plasmodium falciparum interactions with the human placenta

During pregnancy, Plasmodium falciparum-infected erythrocytes cytoadhere to the placenta. Infection is likely initiated at two sites where placental trophoblasts contact maternal blood: 1) via syncytiotrophoblast (STB), a multicellular transporting and biosynthetic layer that forms the surface of chorionic villi and lines the intervillous space, and 2) through invasive cytotrophoblasts, which line uterine vessels that divert blood to the placenta. Here, we investigated mechanisms of infected erythrocyte sequestration in relationship to the microanatomy of the maternal-fetal interface. Histological analyses revealed STB denudation in placental malaria, which brought the stromal cores of villi in direct contact with maternal blood. STB denudation was associated with hemozoin deposition (P = 0.01) and leukocyte infiltration (P = 0.001) and appeared to be a feature of chronic placental malaria. Immunolocalization of infected red blood cell receptors (CD36, ICAM1/CD54, and chondroitin sulfate A) in placentas from uncomplicated pregnancies showed that STB did not stain, while the underlying villous stroma was immunopositive. Invasive cytotrophoblasts expressed ICAM1. In malaria, STB denudation exposed CD36 and chondroitin sulfate A in the villous cores to maternal blood, and STB expressed ICAM1. Finally, we investigated infected erythrocyte adherence to novel receptors by screening an array of 377 glycans. Infected erythrocytes bound Lewis antigens that immunolocalized to STB. Our results suggest that P. falciparum interactions with STB-associated Lewis antigens could initiate placental malaria. Subsequent pathologies, which expose CD36, ICAM1, and chondroitin sulfate A, might propagate the infection.

Changes of human decidual natural killer cells cocultured with YFP-Toxoplasma gondii: implications for abnormal pregnancy

OBJECTIVE

To investigate the changes of human decidual natural killer (dNK) cells cocultured with Toxoplasma gondii in vitro and to infer implications on pregnancy.

DESIGN

Case-control study.

SETTING

College and hospital.

PATIENT(S)

Decidual tissue was obtained from 85 patients undergoing voluntary abortion during the first trimester of gestation (6-12 weeks).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The dNK cells were isolated and infected with YFP-Toxoplasma gondii. Cells were observed by fluorescence and confocal microscopy. The CD56(bright)CD16(-)/CD56(dim)CD16(+) dNK ratio, expression of KIR2DL4, ILT-2, and NKG2D on dNK cells were analyzed by flow cytometry and the cytotoxic activity of infected dNK cells were evaluated.

RESULT(S)

The CD56(dim)CD16(+)/CD56(bright)CD16(-) dNK ratio was significantly elevated at 12, 24, and 48 hours after YFP-T. gondii infection. Expression of KIR2DL4, ILT-2, and NKG2D were increased after infection, but NKG2D were significantly higher than those of KIR2DL4 and ILT-2. Both the CD56(dim)CD16(+)/CD56(bright)CD16(-) dNK ratio and NKG2D expression were correlated with dNK cytotoxic activity.

CONCLUSION(S)

Enhanced dNK cytotoxicity due to increased CD16 and NKG2D expression may contribute to abnormal pregnancy outcomes observed with maternal infection with T. gondii.

[Early stage of Acanthamoeba keratitis]

We present a case of early detected Acanthamoeba keratitis. The patient was a 31 year-old female with keratitis who was referred to our clinic. Upon arrival the patient presented with subepithelial corneal infiltrates and radiating neuritis. In vivo confocal microscopy showed Acanthamoeba cysts and treatment was initiated. Polymerase chain reaction analysis later confirmed the diagnosis and after three months symptoms had abated and vision was 1.0 (6/6). We confirm that an early diagnosis af Acanthamoeba keratitis is pivotal.

Human hydatidosis in Tehran, Iran: a retrospective epidemiological study of surgical cases between 1999 and 2009 at two university medical centers

This study was conducted to evaluate retrospectively 203 patients diagnosed with hydatid cyst disease and treated surgically at two university medical centers between 1999 and 2009 in Tehran, the capital of Iran. Cystic echinococcosis (CE) affected more females 117 (57.6%) than males 86 (42.4%). A remarkable gender difference skewed towards females was observed, and the male/female ratio among CE cases ≤20 and ≥61 years old was 1.18 and 0.52, respectively. The age of the patients ranged from 8 to 82 years, and the age group 21-40 years (42.8%) was the most affected. A significantly higher number of hydatid cysts were recorded in the liver than in other sites (P<0.001), and more females had higher hepatic cysts (48.8%) than males (35.0%). The ratio of hepatic hydatidosis to pulmonary hydatidosis was about 11. There was a relative direct relationship between the ratio of liver to lung cases and age, and this ratio was significantly (P<0.01) higher in individuals >40 years of age (liver/lung ratio ≥43) than in those <40 years of age (liver/lung ratio 2.8-7.6). Unusual cyst locations in kidneys, brain and pelvic area, followed by spleen and spine was also observed. Single organ involvement was found in 95% of the patients, and was more common in females (55.2%) than in males (39.9%). Housewives had the highest rate of infection (53.5%) followed by labourers with 14.8%, which showed a significant difference (P<0.001). Similarly, urban dwellers was also over-represented among the cases (87% urban vs. 13% rural; P<0.001). In 69.5% of cases there was only one cyst, 16.3% had two cysts, 4.7% with three cysts, and 9.5% had four cysts or more. The results showed that further studies are needed to determine the prevalence, economic impact and risk factors of the disease in the area.

Antibodies to a full-length VAR2CSA immunogen are broadly strain-transcendent but do not cross-inhibit different placental-type parasite isolates

The high molecular weight, multidomain VAR2CSA protein mediating adhesion of Plasmodium falciparum-infected erythrocytes in the placenta is the leading candidate for a pregnancy malaria vaccine. However, it has been difficult so far to generate strong and consistent adhesion blocking antibody responses against most single-domain VAR2CSA immunogens. Recent advances in expression of the full-length recombinant protein showed it binds with much greater specificity and affinity to chondroitin sulphate A (CSA) than individual VAR2CSA domains. This raises the possibility that a specific CSA binding pocket(s) is formed in the full length antigen and could be an important target for vaccine development. In this study, we compared the immunogenicity of a full-length VAR2CSA recombinant protein containing all six Duffy binding-like (DBL) domains to that of a three-domain construct (DBL4-6) in mice and rabbits. Animals immunized with either immunogen acquired antibodies reacting with several VAR2CSA individual domains by ELISA, but antibody responses against the highly conserved DBL4 domain were weaker in animals immunized with full-length DBL1-6 recombinant protein compared to DBL4-6 recombinant protein. Both immunogens induced cross-reactive antibodies to several heterologous CSA-binding parasite lines expressing different VAR2CSA orthologues. However, antibodies that inhibited adhesion of parasites to CSA were only elicited in rabbits immunized with full-length immunogen and inhibition was restricted to the homologous CSA-binding parasite. These findings demonstrate that partial and full-length VAR2CSA immunogens induce cross-reactive antibodies, but inhibitory antibody responses to full-length immunogen were highly allele-specific and variable between animal species.

The extent of parasite-associated necrosis in the placenta and foetal tissues of cattle following Neospora caninum infection in early and late gestation correlates with foetal death

The protozoan parasite Neospora caninum is the most frequently diagnosed abortifacient in the UK and a leading cause of abortion worldwide but the mechanisms leading to abortion are not fully understood. The distribution of parasites and the histopathological changes in the placenta and foetus were compared in 12 cows following experimental infection of cattle with N. caninum in early (n=6) and late (n=6) gestation, by PCR, immunohistology, light microscopy and transmission electron microscopy. Twelve uninfected pregnant cattle were used as controls. Infection in early gestation led to foetal death. In the placentae of cattle immediately following foetal death, N. caninum DNA was detected and there was evidence of widespread parasite dissemination. This was associated with extensive focal epithelial necrosis, serum leakage and moderate maternal interstitial mononuclear cell infiltration. In the foetuses, parasites were evident in all tissues examined and were associated with necrosis. In the placenta of cattle infected in late gestation, N. caninum DNA was detected sporadically but parasites were not evident immunohistologically. Small foci of necrosis were seen associated with mild interstitial mononuclear cell infiltration. Detection of N. caninum DNA in the foetuses was sporadic and parasites were demonstrated immunohistologically in brain and spinal cord only, with an associated mononuclear cell infiltration. This data is consistent with uncontrolled parasite spread in an immunologically immature foetus and could, via multiparenchymal necrosis of foetal tissues or the widespread necrosis and inflammation observed in the placenta, be the cause of Neospora-associated abortions.

Disruption of var2csa gene impairs placental malaria associated adhesion phenotype

Infection with Plasmodium falciparum during pregnancy is one of the major causes of malaria related morbidity and mortality in newborn and mothers. The complications of pregnancy-associated malaria result mainly from massive adhesion of Plasmodium falciparum-infected erythrocytes (IE) to chondroitin sulfate A (CSA) present in the placental intervillous blood spaces. Var2CSA, a member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family is the predominant parasite ligand mediating CSA binding. However, experimental evidence suggests that other host receptors, such as hyaluronic acid (HA) and the neonatal Fc receptor, may also support placental binding. Here we used parasites in which var2csa was genetically disrupted to evaluate the contribution of these receptors to placental sequestration and to identify additional adhesion receptors that may be involved in pregnancy-associated malaria. By comparison to the wild-type parasites, the FCR3Δvar2csa mutants could not be selected for HA adhesion, indicating that var2csa is not only essential for IE cytoadhesion to the placental receptor CSA, but also to HA. However, further studies using different pure sources of HA revealed that the previously observed binding results from CSA contamination in the bovine vitreous humor HA preparation. To identify CSA-independent placental interactions, FCR3Δvar2csa mutant parasites were selected for adhesion to the human placental trophoblastic BeWo cell line. BeWo selected parasites revealed a multi-phenotypic adhesion population expressing multiple var genes. However, these parasites did not cytoadhere specifically to the syncytiotrophoblast lining of placental cryosections and were not recognized by sera from malaria-exposed women in a parity dependent manner, indicating that the surface molecules present on the surface of the BeWo selected population are not specifically expressed during the course of pregnancy-associated malaria. Taken together, these results demonstrate that the placental malaria associated phenotype can not be restored in FCR3Δvar2csa mutant parasites and highlight the key role of var2CSA in pregnancy malaria pathogenesis and for vaccine development.

Cutaneous Leishmaniasis during Pregnancy: Exuberant Lesions and Potential Fetal Complications

Cutaneous leishmaniasis affects millions of people worldwide. After observations of atypical lesions in pregnant women at the health centers of Corte de Pedra, Brazil, 9 years of records were reviewed, and 26 pregnant patients were identified. A retrospective case-control study revealed that lesions in pregnant women were much larger than those in nonpregnant patients in an age- and sex-matched group (mean area, 6.08 cm2 vs. 1.46 cm2; P=.008), and many lesions had an exophytic nature. Despite foregoing treatment until after delivery, response to pentavalent antimony therapy was favorable (rate of cure with 1 course of treatment, 85%). High rates of preterm births (10.5%) and stillbirths (10.5%) were reported. Cutaneous leishmaniasis during pregnancy produces distinct lesions and may have adverse fetal effects.

Schistosome-induced pathology is exacerbated and Th2 polarization is enhanced during pregnancy

THE AIM of this study was to investigate the immunopathological impact of pregnancy on an ongoing experimental schistosomiasis infection.

MATERIALS AND METHODS

Female BALB/c mice were randomly divided into three groups (A, B and C) of 15 animals each. The mice in Groups A and B were infected with 40 S. mansoni cercariae, percutaneously. Six weeks post-infection, the mice in Groups B and C (schistosome-naive controls) were mated. Schistosome-induced morbidity and cytokine recall responses were subsequently evaluated at weeks 7 and 8 post-infection.

RESULTS

Hepatic and pulmonary lesions resulting from trapped schistosome eggs were more frequent and more severe in Group B mice than in Group A mice. Group C mice had suppressed mitogen-stimulated interleukin 4 (IL-4) but maintained high intereferon gamma (IFN-gamma) responses. In contrast, Group A mice had elevated mitogen- and parasite-specific IL-4 but muted IFN-gamma responses. Group B mice had an early (week 7) high IL-4 response, even higher than in group A mice.

CONCLUSION

Taken together the data suggest that pregnancy exacerbates schistosome-induced morbidity, probably through up-regulation of parasite-specific IL-4.

Malaria in pregnancy: pathogenesis and immunity

Understanding of the biological basis for susceptibility to malaria in pregnancy was recently advanced by the discovery that erythrocytes infected with Plasmodium falciparum accumulate in the placenta through adhesion to molecules such as chondroitin sulphate A. Antibody recognition of placental infected erythrocytes is dependent on sex and gravidity, and could protect from malaria complications. Moreover, a conserved parasite gene-var2csa-has been associated with placental malaria, suggesting that its product might be an appropriate vaccine candidate. By contrast, our understanding of placental immunopathology and how this contributes to anaemia and low birthweight remains restricted, although inflammatory cytokines produced by T cells, macrophages, and other cells are clearly important. Studies that unravel the role of host response to malaria in pathology and protection in the placenta, and that dissect the relation between timing of infection and outcome, could allow improved targeting of preventive treatments and development of a vaccine for use in pregnant women.

Toxoplasmosis in captive Bennett's wallabies (Macropus rufogriseus) in Argentina

Wallabies and other Australian marsupials are among the most susceptible species to Toxoplasma gondii. Fatal generalized toxoplasmosis was diagnosed in two captive 3 year-old female Bennett's wallabies (Macropus rufogriseus) from Argentina (w 1 and w 2) with a history of sudden death. Both animals had internal joeys which died 2 days after their mothers. Serologically, both females and one adult male without clinical signs from the same enclosure (w 3) had antibody titers for T. gondii>or=800 by the modified agglutination test (MAT); another adult male (w 4) was negative (MAT titer<25). Microscopically, tachyzoites were observed associated to non-suppurative meningoencephalitis, hepatitis, myositis, myocarditis and severe enteritis in hematoxylin and eosin stained sections from both w 1 and w 2. Immunohistochemically, parasites in heart, brain and liver sections of both female wallabies reacted with T. gondii antiserum. T. gondii was isolated from brain tissues of w 1 and w 2 by bioassay in mice and by culture in bovine monocytes and both isolates were cryopreserved. Genomic DNA was isolated from tachyzoites grown in cultures derived from both animals. The primer pair B22/B23 specific for T. gondii produced 115bp amplicons on poliacrylamide electrophoretic gels. Stray cats were suspected as the possible source of infection. Not all infected macropods were ill, showing that the infection may be asymptomatic and is not always fatal. A vertical infection could not be proved in the joey from w 2. As far as we know, this is the first confirmed report of toxoplasmosis in Bennet's wallabies in Argentina.

An unusual presentation of placental malaria: a single persisting nidus of sequestered parasites

Placental malaria caused by Plasmodium falciparum is a public health concern in tropical countries. Peripheral blood smears to detect placental malaria are often negative, and recrudescences are common during pregnancy. We performed placental histology on a series of first-time mothers delivering in an area endemic for P falciparum. A single nidus of malaria-infected erythrocytes was identified by placental histology in a single intervillous space from a woman who had no other evidence of peripheral or placental blood parasitemia. This finding suggests ring stage-infected erythrocytes sequester in vivo, or P falciparum can persist as a dormant blood stage form.

Role of endogenous transplacental transmission in toxoplasmosis in sheep

To investigate the potential role of endogenous transplacental transmission of Toxoplasma gondii, 31 seropositive ewes presumed to be persistently infected with the parasite and 15 seronegative ewes were mated and monitored throughout pregnancy and lambing. Antibody titres were determined in precolostral sera from the liveborn lambs and in thoracic fluid from the dead lambs. A PCR for the B1 gene of T gondii was applied to the placentas from all the ewes and to the brains of the stillborn lambs. Samples of brain, lung, liver, spleen and heart from the dead lambs were examined by histopathology. No evidence of toxoplasmosis was detected by histopathology or PCR in any of the samples, but low titres of antibody to T gondii were detected in two liveborn, healthy offspring of a seropositive ewe by the immunofluorescent antibody test (3.2 per cent of pregnancies and 4.1 per cent of lambs in the seropositive group). Antibody to specific antigens of T gondii was demonstrated in sera from these two lambs by Western blotting.

Hypertension and maternal-fetal conflict during placental malaria

BACKGROUND

Malaria and hypertension are major causes of maternal mortality in tropical countries, especially during first pregnancies, but evidence for a relationship between these syndromes is contradictory.

METHODS AND FINDINGS

In a cross-sectional survey of Tanzanian parturients, the rate of hypertension was similar in placental malaria (PM)-positive (11/85 = 13%) and PM-negative (73/602 = 12%) individuals. However, we found that PM was associated with hypertension in first-time mothers aged 18-20 y but not other mothers. Hypertension was also associated with histologic features of chronic malaria, which is common in first-time mothers. Levels of soluble vascular endothelial growth factor receptor 1 (sVEGFR1), a preeclampsia biomarker, were elevated in first-time mothers with either PM, hypertension, or both, but levels were not elevated in other mothers with these conditions. In first-time mothers with PM, the inflammatory mediator vascular endothelial growth factor (VEGF) was localized to maternal macrophages in the placenta, while sVEGFR1, its soluble inhibitor, was localized to the fetal trophoblast.

CONCLUSIONS

The data suggest that maternal-fetal conflict involving the VEGF pathway occurs during PM, and that sVEGFR1 may be involved in the relationship between chronic PM and hypertension in first-time mothers. Because placental inflammation causes poor fetal outcomes, we hypothesize that fetal mechanisms that promote sVEGFR1 expression may be under selective pressure during first pregnancies in malaria-endemic areas.

Comparison of Neospora caninum distribution, parasite loads and lesions between epidemic and endemic bovine abortion cases

It has been suggested that the abortion herd pattern could influence bovine foetal neosporosis. Here, a comparison of (i) Neospora caninum DNA-detectability by PCR, (ii) N. caninum-associated lesions and (iii) parasite loads in target organs was made between epidemic and endemic abortion cases. We observed that N. caninum DNA was predominantly detected in more than one organ in the foetuses from herds with epizootic rather than endemic abortion cases (P<0.05, Fisher F-test). The highest parasite burdens were found in the heart in foetuses from outbreaks of epidemic abortion and in the brain in endemic cases (P<0.05, Kruskal-Wallis H-test). Moreover, foetuses from epidemic outbreaks had significantly higher parasite burdens in heart (P<0.05, Mann-Whitney U-test) than endemic abortion cases. Epidemic abortion cases showed higher lesion frequencies in liver (P<0.05, Fisher F-test). This report confirms that the abortion herd pattern is an important factor that influences pathogenesis in natural N. caninum infections.

High prevalence of placental malaria and low birth weight in Sahelian periurban area

The impact of placental malaria in African urban areas is poorly documented. We therefore conducted a study during the rainy season in Dakar, an area with low malaria transmission. Two groups of delivering women were enrolled according to the detection of PfHRP2 in placental blood. Ten percent of the women were positive for parasites in the placenta, and microscopic examination showed, respectively, 17%, 22%, and 44% of past, acute, and chronic infection. The mean birth weight decreased drastically with the infection of the placenta (2,684 +/- 67 versus 3,085 +/- 66 g for controls), particularly with chronic infection. Chronic infection was not linked with parasiteamia in maternal venous blood. Seventy-six percent of positive women were anemic (46% of the controls). Severe anemia was also associated with chronic infection. Long-lasting infections are the most deleterious to mother and infant and are most likely associated with drug resistance of parasites.

Pregnancy outcomes associated with Plasmodium vivax malaria in northeastern Venezuela

Although Plasmodium vivax is increasingly recognized as an important cause of morbidity in pregnancy in low malaria-transmission areas of Asia, little is know about the epidemiologic and clinical profiles of P. vivax in pregnant women in Latin America. We describe the clinical features and pregnancy outcomes in a series of 12 cases of P. vivax malaria in pregnant women complicated in some by miscarriage or preterm deliveries and in others with significant degrees of anemia and thrombocytopenia in a population where P. vivax is endemic in northeastern Venezuela.

Survey of Neospora caninum infection by nested PCR in aborted fetuses from dairy farms in Aguascalientes, Mexico

The aim of this study was to determine by nested PCR probe the presence of Neospora caninum in fetal brain tissue from aborted dairy fetuses in Aguascalientes, a state in the central part of Mexico. Forty-four fetal brains from eight dairy farms were analyzed using single tube nested PCR probe with primers NF1, NS2, NR1 and SR1, with histopathology as the reference technique. From the 44 bovine fetuses studied, 35 (80%) were diagnosed as being infected by N. caninum using PCR probe and 20 (45%) were considered positive by histopathology, because they had lesions suggestive of bovine neosporosis. Fair agreement was observed (31%) between both probes. The age of aborting cows ranged from 1.6 to 2.9-year-old in 17 (49%) of the positive cases diagnosed by PCR. Gestational ages of aborted fetuses ranged from <3 to 9 months, with average of 5.6 months, and no statistical significant difference was observed when ages of infected and no infected fetuses were compared (P > 0.05). The frequency of N. caninum positive cases observed could be considered to be higher than other areas of Mexico and other countries.

Placentitis associated with leishmaniasis in a dog

A 1.5-year-old Coonhound from Maryland aborted 7 fetuses. Placenta and internal tissues of 1 fetus were examined histologically. The predominant lesion was placentitis characterized by necrosis and infiltration of mixed leukocytes. Numerous Leishmania spp amastigotes were identified in placental trophoblasts, and the diagnosis was confirmed by use of immunohistochemical staining with Leishmania-specific antibodies. Protozoa were not found in the fetal tissues. An indirect fluorescent antibody test yielded a serum titer of 1:100, and a recombinant K39 immunoassay of serum yielded positive results for the K39 Leishmania antigen.

Transplacental transmission and abortion in cows administered Neospora caninum oocysts

Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1500 to 115,000 oocysts through an esophageal tube. Seventeen of the cows became seropositive, indicating acquisition of infection, whereas 8 negative control cows remained seronegative (P < 0.001). Offspring were examined using serology, histology, immunohistochemistry, parasite isolation, and polymerase chain reaction (PCR). Six offspring were infected and 1 of them was aborted. The aborted fetus had typical lesions and positive immunohistochemistry and PCR for N. caninum. All 6 cows with infected offspring had continuously rising antibody titers, whereas 10 of 11 infected cows with uninfected offspring had falling titers after an early apex. The risk of transplacental transmission was increased by later exposure times during gestation and by the dose of oocysts (P < 0.01 for the 2 combined variables). The lowest dose of oocysts, when administered after the 160th day of gestation, caused transplacental infection in 1 of 2 animals. This study demonstrates that infection with N. caninum oocysts can cause transplacental transmission and abortion in cattle.

Malaria in pregnant Cameroonian women: the effect of age and gravidity on submicroscopic and mixed-species infections and multiple parasite genotypes

Polymerase chain reaction (PCR)-based methods were used to investigate malaria in pregnant women residing in Yaounde, Cameroon. Microscopy and species-specific PCR-based diagnosis show that at delivery 82.4% of the women were infected with Plasmodium falciparum (27.5% blood-smear positive and 54.9% submicroscopic infections). The prevalence of P. malariae and P. ovale was 7.6% and 2.5%, respectively, with 9.4% infected with more than one species. Based on genotyping of the merozoite surface protein 1 (msp-1) and msp-2 alleles, the mean number of genetically different P. falciparum parasites in peripheral blood was 3.4 (range = 1-9) and 3.5 (range 1-8) in the placenta. Plasmodium falciparum detected by microscopy and PCR as well as mixed-species infections were significantly higher in women < or = 20 years old and paucigravidae, but maternal anemia was associated only with microscopic detection of parasites. Neither submicroscopic infections nor number of parasite genotypes decreased significantly with age or gravidity. Thus, pregnancy-associated immunity helps reduce malaria to submicroscopic levels, but does not reduce the number of circulating parasite genotypes.

Risk factors for placental malaria and its effect on pregnancy outcome in Yaounde, Cameroon

Between 1996 and 2001, the prevalence of placental malaria in pregnant women living in Yaounde, Cameroon and its effect on pregnancy outcome were evaluated with respect to gravidity and maternal age. Results showed that 19.9% of the women had placental malaria at delivery. After adjusting for relevant covariates, the major risk factor for placental malaria was an age < 25 years old. Placental malaria significantly increased the prevalence of anemia in women regardless of gravidity or age. In addition, the mean infant birth weight was lower and the percentage of pre-term deliveries (PTDs) and low birth weight (LBW) babies were higher in primigravidae and women < 20 years of age who had placental malaria. However, in a multivariate regression model taking relevant covariates into consideration, the major risk factor for PTDs was maternal anemia, and maternal anemia as well as first and second pregnancies were important risk factors for LBW babies.

Clinical features and pathogenesis of severe malaria

A major change in recent years has been the recognition that severe malaria, predominantly caused by Plasmodium falciparum, is a complex multi-system disorder presenting with a range of clinical features. It is becoming apparent that syndromes such as cerebral malaria, which were previously considered relatively clear cut, are not homogenous conditions with a single pathological correlate or pathogenic process. This creates challenges both for elucidating key mechanisms of disease and for identifying suitable targets for adjunctive therapy. The development of severe malaria probably results from a combination of parasite-specific factors, such as adhesion and sequestration in the vasculature and the release of bioactive molecules, together with host inflammatory responses. These include cytokine and chemokine production and cellular infiltrates. This review summarizes progress in several areas presented at a recent meeting.

[Placental lesions in human Trypanosoma cruzi infection]

This histopathological study analyzes placentas of babies congenitally infected with T. cruzi (M+B+), or babies not infected but born from infected- (M+B-), or non infected-mothers (M-B-). Placentas M+B+ showed lesions of chorionitis, chorioamnionitis and cord edema with lymphocyte infiltration, whereas such lesions were infiltrated only with polymorphonuclear cells in M+B- and M-B- placentas. Parasites were found in M+B+ placentas, in fibroblasts and macrophages of chorion, membranes, chorionic plate, mainly in the area of membrane insertion, as well as in cells of Wharton jelly and myocytes of umbilical cord vessels. These results suggest that the materno-fetal transmission of parasites occurs mainly through the marginal sinus, spreading into the chorionic plate infecting fibroblasts and macrophages so far as to found a fetal vessel, inducing a fetal infection by hematogenous route.

Monocyte Activation and T Cell Inhibition inPlasmodium falciparum–Infected Placenta

BACKGROUND

During healthy pregnancy, T helper (Th) 1-type and inflammatory-type responses are down-regulated, and Th2-type and proinflammatory-type responses predominate. In Plasmodium falciparum-infected females, these responses induce enhanced production of tumor necrosis factor- alpha and interferon- gamma.

METHODS

To assess the respective implication of monocytes and T cells in this placental immunomodulation, we cocultured cells from delivering females living in an area where malaria is endemic. Monocytes and T cells from both peripheral and intervillous blood were crossed in in vitro cultures, to compare the proliferative response to several antigens. Moreover, monocyte cell-surface molecules were quantified by flow cytometry.

RESULTS

Coculture results confirmed placental immunomodulation and suggested that the most affected cells are not the intervillous monocytes, which are as able to present the antigen as the peripheral monocytes, but the intervillous T cells. Monocyte staining showed significant increases in human leukocyte antigen D-related, CD54, CD80, and CD86 surface markers in intervillous blood, compared with peripheral blood, which suggests a relative activation of monocytes in the placenta.

CONCLUSION

A state of T cell deactivation and monocyte activation is present at delivery. The T cell deactivation in reaction to purified protein derivative could be explained by the presence of local T cell immunoregulatory factors.

The effects of Plasmodium falciparum and P. vivax infections on placental histopathology in an area of low malaria transmission

Placental histopathology was studied in a cohort of 204 women living in an area of low Plasmodium falciparum and P. vivax malaria transmission. Detection of malaria antenatally was active, by weekly peripheral blood smears, and all infections were treated. Significant histopathologic placental malaria changes (increased malaria pigment, cytotrophoblastic prominence, and presence of parasites) were found only in a minority of women who had P. falciparum infections in pregnancy. These changes were significantly more frequent in women with evidence of peripheral blood infection close to delivery and only in these cases were placental inflammatory cells increased. Antenatal P. vivax infection was associated only with the presence of malaria pigment in the placenta. All placental infections diagnosed by blood smear and 32.4% (12 of 37) diagnosed by histopathology were associated with patent peripheral parasitemia. This study indicates that prompt treatment of peripheral parasitemias during pregnancy limits placental pathology. The effect on birth weight reduction may not result from irreversible placental changes but from the acute insult of infection. These findings emphasize the importance of treating malaria in pregnancy promptly with effective antimalarial drugs.

Cytokine profiles in peripheral, placental and cord blood in pregnant women from an area endemic for Plasmodium falciparum

During gestation, inflammatory cytokines are sometimes more abundant than growth-promoting cytokines, and via direct or indirect effects, proinflammatory cytokines lead to intrauterine growth retardation. We used an enzyme-linked immunosorbent assay to measure the concentrations of three proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin-12 (IL-12p40), as well as interleukin-15 (IL-15) and monocyte chemotactic protein-1 (MCP-1), in plasma from peripheral, placental and cord blood of thirty pregnant Gabonese women. All of these women lived in Libreville and Lambaréné, two malaria hyperendemic areas. IL-12p40 concentrations were higher in cord blood than in placental or peripheral blood. The MCP-1 concentration was higher in placental blood, than in peripheral or cord blood. IL-15 concentrations were similar at the three sites. MCP-1 concentrations were higher in the placentas of primiparous women than in those of multiparous women. The highest concentrations were found in infected placentas. IL-15 concentrations were significantly higher in peripheral and placental plasma from uninfected women than in plasma from infected women. Strong positive correlations were found between placental and cord IL-12p40 and IL-15 plasma concentrations. Likewise, a strong positive correlation was found between IL-12p40 and MCP-1 concentrations in cord and peripheral plasma. These results suggest that placental, maternal peripheral and cord blood present different cytokine profiles in response to P. falciparum.

Prenatal diagnosis of congenital Chagas' disease(American trypanosomiasis)

The prenatal diagnosis of congenital transmission of Chagas' disease in a pregnant woman with the indeterminate form of the disease is reported. Sonography revealed fetal hydrops at 31 weeks' gestation. Anti-Trypanosoma cruzi IgM and IgG antibodies were negative in the fetal blood sampled by cordocentesis, but T. cruzi trypomastigotes were found in its buffy coat. Owing to anemia, in utero exchange transfusion was undertaken, but fetal demise ensued. Labor was induced and a stillborn infant weighing 2030 g was delivered. The pathological examination revealed placentitis and meningoencephalitis, myocarditis and splenitis in the stillborn fetus. Amastigotes were found in the myocardium, brain and placenta.

Effect of Maternal HIV and Malaria Infection on Pregnancy and Perinatal Outcome in Zimbabwe

OBJECTIVE

To investigate the effect of isolated or concomitant infection with malaria and HIV on pregnancy and neonatal outcome.

METHODS

Data were collected on pregnant women admitted during the rainy seasons in the obstetric division of a district referral hospital in northern Zimbabwe in 2000 and 2001. The effects of malaria and HIV infection were determined by multivariate analysis.

RESULTS

The prevalence of HIV seropositivity and symptomatic malaria in 986 pregnant women was 8.3% and 14.7%, respectively. HIV-infected women were more likely to develop malaria attacks during pregnancy than seronegative women (odds ratio [OR] = 3.96, 95% confidence interval (CI): 2.42-6.46). Malaria and HIV infections were associated with increased risk of stillbirth (OR = 4.74, 95% CI: 1.34-16.78) and preterm delivery (OR = 4.10, 95% CI: 2.17-7.75), respectively. They were independently associated with increased risk of low birth weight (malaria: OR = 10.09, 95% CI: 6.50-15.65; HIV: OR = 3.16, 95% CI: 1.80-5.54) and very low birth weight (malaria: OR = 5.04, 95% CI: 1.00-25.43; HIV: OR = 10.74, 95% CI: 2.12-54.41), low Apgar score (malaria: OR = 4.45, 95% CI: 1.42-13.94; HIV: OR = 5.94, 95% CI: 1.66-21.30), and fetal growth restriction (malaria: OR = 3.98, 95% CI: 2.51-6.30; HIV: OR = 4.07, 95% CI: 2.40-6.92). Dual infection with malaria and HIV was associated with increased risk of maternal, perinatal, and early infant death.

CONCLUSIONS

Women with single HIV or malaria infection have a significantly increased risk of adverse outcomes of pregnancy and childbirth. Dual infection has additional detrimental effects on maternal and infant survival in an area where HIV and malaria coexist.

The epidemiology and consequences of maternal malaria: a review of immunological basis

Millions of women who become pregnant in malaria-endemic areas are at increased risk of contracting malaria infection that jeopardises the outcome of pregnancy. The complication of this infection for mother and baby are considerable. In absence of any other reason, it was thought that the increased risk of infection during pregnancy was related to suppression of pre-existing malaria immunity. Although this concept is plausible, the significantly higher risk of maternal malaria and consequences in primigravidae compared with multigravidae suggests that there are more to mere immunosuppression in pregnancy. The mechanisms underlying some of the striking epidemiological and clinical features of malaria in pregnancy could be related to differences in the strains of parasite populations infecting pregnant women occasioned by the cyto-adherent properties of human placenta, presence or absence of anti-adhesion antibodies acquired from previous pregnancies or the elevated production of some pro-inflammatory cytokines in response to parasitisation of human placenta. Malaria infection of placenta causes a shift from Th2 to Th1 cytokine profile that may be detrimental to pregnancy. The increased susceptibility in the first pregnancy can be explained by the absence of anti-adhesion antibody in the primigravida that is being exposed for the first time to a different strain of malaria parasite sub-population that adhere exclusively to chondroitin sulphate A and hyaluronic acid (HA) in the placenta. In reviewing the epidemiology and consequences of maternal malaria, we have highlighted possible immunological and molecular basis that could account for the higher impact of malaria in pregnancy especially among primigravidae. These factors could be the basis for future research and vaccine formulation.