Transplacental transfer of total immunoglobulin G and antibodies to Plasmodium falciparum antigens between the 24th week of gestation and term.

Full-term newborns have antibody (Ab) repertoires and levels similar to their mothers to help protect them from environmental pathogens. Unfortunately, preterm babies, especially those born < 34 weeks, have reduced levels of protective antibodies. In Africa, antibodies to Plasmodium falciparum are important in protection from malaria. This study investigated the transfer of total IgG and antibodies to 9 P. falciparum antigens and tetanus toxoid between 24 weeks and term. Paired maternal and cord samples from 166 preterm (24-37 weeks) and 154 term deliveries were used. Transfer efficiency was expressed as the ratio of Ab levels in cord to maternal plasma (CMR). At 24-25 weeks, CMR ranged from 0.31 to 0.94 for the different antigens; the rate of transfer was similar for all antigens between 24 and 40 weeks; resulting in median CMR of 0.49-0.95 at term. Babies of mothers with hypergammaglobulinemia and normal IgG levels had similar amounts of IgG, supporting data that saturation of the neonatal Fc-receptor occurs at ~ 16 mg IgG/ml. Thus, babies born prior to 34-35 weeks in Africa are likely to have reduced Ab levels to some, but not all antigens. Since IgG transfer is Fc-mediated, why differences exist in CMR among the antigens warrants further investigation.

Prevalence of alpha and beta haemolysin among blood group O donors in Bamenda, Cameroon.

Background: The occurrence of high titres of alpha (anti-A) and beta (anti-B) haemolysin immunoglobulin G antibodies in blood causes haemolysis during blood transfusion from a group O donor, commonly and inappropriately known as the 'universal blood donor', to a group A, B or AB recipient. Surprisingly, haemolysin testing is not routinely done during blood transfusion services in Bamenda, Cameroon. Objective: This study aimed to determine the prevalence of haemolysin among blood group 'O' donors at the Regional Hospital Bamenda Blood Bank, Bamenda, Cameroon. Methods: This was a cross-sectional descriptive study carried out between June and September 2020 at the Regional Hospital Bamenda Blood Bank, Bamenda, Cameroon. Blood group O donors who were free from transfusion-transmissible infections were selected systematically and serially and their serum tested for the presence of haemolysin. Haemolysin titres were determined, and titres ≥ 8 were considered significant. The associations between haemolysin prevalence and age group, gender and Rhesus D blood group were determined using the chi-square test. Results: The prevalence of haemolysin among the 480 study participants was 52.1% and significant haemolysin titres were detected in 18.5%. There was no association between haemolysin and gender, age group or the Rhesus D blood group. Conclusion: The prevalence of significant titres of haemolysin among participants in this study was high. There is the need to test for haemolysin in blood group O donors to prevent the potential risk to blood group A, B, and AB recipients and to provide safer blood for transfusion.

Haematological reference intervals for healthy adults in Bamenda, Cameroon.

BACKGROUND: In the era of evidence-based medicine, haematological reference intervals are essential for the interpretation of data for clinical decision-making, monitoring of treatment and research. It is not uncommon that reference intervals used in most African countries have been obtained from published scientific literature, textbooks, reagent/instrument manuals. OBJECTIVE: The aim of this study was to determine haematological reference intervals of healthy adults in Bamenda, Cameroon. METHODS: This was a cross-sectional study conducted between June and November 2015. Participants were voluntary blood donors at the Blood Bank Service of the Regional Hospital Bamenda aged between 18 and 65 years. The mean, median and standard deviation of the mean were calculated for each haematological parameter. The 95th percentile reference intervals were determined using the 2.5th and 97.5th percentile. The differences between gender for all the parameters were evaluated using the Kruskal-Wallis test. Significance was determined at the 95% confidence level. RESULTS: Out of a total of 340 participants, 202 (59.4%) were men and 138 (40.6%) were women. The median red blood cell, haemoglobin, haematocrit and mean cell haemoglobin concentration were significantly higher in men than women (p < 0.001). The median white blood cell, absolute lymphocytes count, absolute granulocytes and platelet counts for men were significantly lower than those for women (p < 0.011). CONCLUSION: We propose that the present established haematological reference intervals in this study should be used for clinical management of patients and interpretation of laboratory data for research in Bamenda.

Preventing unsafe abortion: Achievements and challenges of a global FIGO initiative.

FIGO established a Working Group on the Prevention of Unsafe Abortion in 2007 and a parallel program or "Initiative" with the same name. The initiative involved 46 FIGO member societies from seven regions: South-Southeast Asia, Eastern-Central Europe and Central Asia, North Africa and Eastern Mediterranean, Eastern-Central-Southern Africa, Western-Central Africa, Central America and Caribbean, and South America. Each society working in collaboration with the corresponding Ministry of Health and other agencies conducted a situational analysis and prepared a plan of action based on the findings. Such plans of action are continuously monitored by annual evaluation of the progress in the implementation at regional workshops. A substantial progress has been achieved in providing legal and safe abortion services, replacing curettage for manual vacuum aspiration or misoprostol and introducing and expanding postabortion contraception with emphasis on long-acting methods, such as IUDs and contraceptive implants.

Timing of the human prenatal antibody response to Plasmodium falciparum antigens.

Plasmodium falciparum (Pf)-specific T- and B-cell responses may be present at birth; however, when during fetal development antibodies are produced is unknown. Accordingly, cord blood samples from 232 preterm (20-37 weeks of gestation) and 450 term (≥37 weeks) babies were screened for IgM to Pf blood-stage antigens MSP1, MSP2, AMA1, EBA175 and RESA. Overall, 25% [95% CI = 22-28%] of the 682 newborns were positive for IgM to ≥1 Pf antigens with the earliest response occurring at 22 weeks. Interestingly, the odds of being positive for cord blood Pf IgM decreased with gestational age (adjusted OR [95% CI] at 20-31 weeks = 2.55 [1.14-5.85] and at 32-36 weeks = 1.97 [0.92-4.29], with ≥37 weeks as reference); however, preterm and term newborns had similar levels of Pf IgM and recognized a comparable breadth of antigens. Having cord blood Pf IgM was associated with placental malaria (adjusted OR [95% CI] = 2.37 [1.25-4.54]). To determine if in utero exposure occurred via transplacental transfer of Pf-IgG immune complexes (IC), IC containing MSP1 and MSP2 were measured in plasma of 242 mother-newborn pairs. Among newborns of IC-positive mothers (77/242), the proportion of cord samples with Pf IC increased with gestational age but was not associated with Pf IgM, suggesting that fetal B cells early in gestation had not been primed by IC. Finally, when cord mononuclear cells from 64 term newborns were cultured in vitro, only 11% (7/64) of supernatants had Pf IgM; whereas, 95% (61/64) contained secreted Pf IgG. These data suggest fetal B cells are capable of making Pf-specific IgM from early in the second trimester and undergo isotype switching to IgG towards term.

Influence of Intermittent Preventive Treatment on Antibodies to VAR2CSA in Pregnant Cameroonian Women.

Intermittent preventive treatment (IPT) and insecticide-treated bed nets are the standard of care for preventing malaria in pregnant women. Since these preventive measures reduce exposure to malaria, their influence on the antibody (Ab) response to the parasite antigen VAR2CSA was evaluated in pregnant Cameroonian women exposed to holoendemic malaria. Ab levels to full-length VAR2CSA (FV2), variants of the six Duffy binding like (DBL) domains, and proportion of high avidity Ab to FV2 were measured longitudinally in 92 women before and 147 women after IPT. As predicted, reduced exposure interfered with acquisition of Ab in primigravidae, with 71% primigravidae being seronegative to FV2 at delivery. Use of IPT for > 13 weeks by multigravidae resulted in 26% of women being seronegative at delivery and a significant reduction in Ab levels to FV2, DBL5, DBL6, proportion of high avidity Ab to FV2, and number of variants recognized. Thus, in women using IPT important immune responses were not acquired by primigravidae and reduced in a portion of multigravidae, especially women with one to two previous pregnancies. Longitudinal data from individual multigravidae on IPT suggest that lower Ab levels most likely resulted from lack of boosting of the VAR2CSA response and not from a short-lived Ab response.

Comparison of the specificity of antibodies to VAR2CSA in Cameroonian multigravidae with and without placental malaria: a retrospective case-control study.

BACKGROUND: Antibodies (Ab) to VAR2CSA prevent Plasmodium falciparum-infected erythrocytes from sequestrating in the placenta, i.e., prevent placental malaria (PM). The specificity of Ab to VAR2CSA associated with absence of PM is unknown. Accordingly, differences in the specificity of Ab to VAR2CSA were compared between multigravidae with and without PM who had Ab to VAR2CSA. METHODS: In a retrospective case-control study, plasma collected from Cameroonian multigravidae with (n = 96) and without (n = 324) PM were screened in 21 assays that measured antibody levels to full length VAR2CSA (FV2), individual VAR2CSA DBL domains, VAR2CSA domains from different genetic backgrounds (variants), as well as proportion of high avidity Ab to FV2. RESULTS: Multigravidae with and without PM had similar levels of Ab to FV2, the six VAR2CSA DBL domains and different variants, while the proportion of high avidity Ab to FV2 was significantly higher in women without PM at delivery (p = 0.0030) compared to women with PM. In a logistic regression model adjusted for gravidity and age, the percentage of high avidity Ab to FV2 was associated with reduced likelihood of PM in multigravidae. A 5 % increase in proportion of high avidity Ab to FV2 was associated with a nearly 15 % lower likelihood of PM. CONCLUSION: Ab avidity to FV2 may be an important indicator of immunity to PM.

Guidelines and tools for organizing and conducting maternal death reviews.

Maternal death reviews (MDRs) provide the multidisciplinary maternity care team with a process to conduct in-depth review of the health care and circumstances surrounding maternal deaths. From these reviews, recommendations to improve care in primary, secondary, and tertiary healthcare settings can be made. Practical guidelines and training curricula for MDRs are lacking. To fill this gap, a manual comprising guidelines and tools to help health professionals conduct structured MDRs was developed through the FIGO LOGIC initiative.

Training health professionals in conducting maternal death reviews.

In countries where maternal death review (MDR) sessions are proposed as an intervention to improve quality of obstetric care, training focuses on the theory behind this method. However, experience shows that health staff lack confidence to apply the theory if they have not attended a practical training session. To address this problem, a training curriculum based on the new guidelines from the FIGO Leadership in Obstetrics and Gynecology for Impact and Change (LOGIC) Initiative for preparing and conducting MDR sessions was designed and tested in Cameroon. This curriculum is competency-based and consists primarily of practical individual or group exercises.

The impact of signing a memorandum of understanding on reproductive health with the Ministry of Public Health in Cameroon.

Health statistics relating to Millennium Development Goals 4 and 5 are poor for most low-resource countries. Professional societies can assist governments to improve these health indicators. For an effective collaboration, the Society of Gynaecologists and Obstetricians Cameroon (SOGOC) and the Ministry of Public Health signed a memorandum of understanding on reproductive health. A major consequence of this collaboration was the ease of transfer of competence associated with SOGOC adopting a monitoring and evaluation role, which has improved quality of care. The impact of this collaboration for the Society has been significant; SOGOC is recognized as a partner and has an opportunity to play a leadership role in issues concerning reproductive health.

Expanding the use of manual vacuum aspiration for incomplete abortion in selected health institutions in Yaoundé, Cameroon.

Preference for manual vacuum aspiration (MVA) and its use for the treatment of incomplete abortion were evaluated among 52 healthcare professionals in 7 Yaoundé hospitals in Cameroon. All but one healthcare professional preferred MVA; however, this technique was available at all times in only two hospitals. In some hospitals, MVA use was only available during the day, while in others it was not available at all. Based on these findings, MVA kits were obtained from the International Federation of Gynecology and Obstetrics (FIGO) for training and to supply selected hospitals. The result was a dramatic increase in the use of MVA in all of the hospitals that received the kits. In one hospital, no kits were received; however, the staff had been sensitized to the problem and the equipment belonging to one of the physicians was put into service. The successful experience of this pilot project provides a rationale for expanding MVA use for incomplete abortion to the entire country.

Contribution of obstetrics and gynecology societies in West and Central African countries to the prevention of unsafe abortion.

Unsafe abortion is a major public health issue in low-resource countries. In the countries of West and Central Africa, abortion-related maternal mortality rates are extremely high, the prevalence of modern contraceptive use is very low, and the unmet need for family planning is also high. The International Federation of Gynecology and Obstetrics (FIGO) Initiative for the Prevention of Unsafe Abortion and its Consequences has contributed substantially toward increasing awareness of the problem of abortion, bringing abortion-related issues to the attention of the professional societies, individual gynecologists and obstetricians, Ministries of Health, healthcare providers, and to the community in general. The promotion of quality postabortion care including the use of manual vacuum aspiration, misoprostol, and postabortion contraception has greatly improved access to services; however, there is still a long way to go.

The antibody response of pregnant Cameroonian women to VAR2CSA ID1-ID2a, a small recombinant protein containing the CSA-binding site.

In pregnant women, Plasmodium falciparum-infected erythrocytes expressing the VAR2CSA antigen bind to chondroitin sulfate A in the placenta causing placental malaria. The binding site of VAR2CSA is present in the ID1-ID2a region. This study sought to determine if pregnant Cameroonian women naturally acquire antibodies to ID1-ID2a and if antibodies to ID1-ID2a correlate with absence of placental malaria at delivery. Antibody levels to full-length VAR2CSA and ID1-ID2a were measured in plasma samples from 745 pregnant Cameroonian women, 144 Cameroonian men, and 66 US subjects. IgM levels and IgG avidity to ID1-ID2a were also determined. As expected, antibodies to ID1-ID2a were absent in US controls. Although pregnant Cameroonian women developed increasing levels of antibodies to full-length VAR2CSA during pregnancy, no increase in either IgM or IgG to ID1-ID2a was observed. Surprisingly, no differences in antibody levels to ID1-ID2a were detected between Cameroonian men and pregnant women. For example, in rural settings only 8-9% of males had antibodies to full-length VAR2CSA, but 90-96% had antibodies to ID1-ID2a. In addition, no significant difference in the avidity of IgG to ID1-ID2a was found between pregnant women and Cameroonian men, and no correlation between antibody levels at delivery and absence of placental malaria was found. Thus, the response to ID1-ID2a was not pregnancy specific, but predominantly against cross-reactivity epitopes, which may have been induced by other PfEMP1 antigens, malarial antigens, or microbes. Currently, ID1-ID2a is a leading vaccine candidate, since it binds to the CSA with the same affinity as the full-length molecule and elicits binding-inhibitory antibodies in animals. Further studies are needed to determine if the presence of naturally acquired cross-reactive antibodies in women living in malaria endemic countries will alter the response to ID1-ID2a following vaccination with ID1-ID2a.

Cord blood Vγ2Vδ2 T cells provide a molecular marker for the influence of pregnancy-associated malaria on neonatal immunity.

BACKGROUND: Plasmodium falciparum placental infection primes the fetal immune system and alters infant immunity. Mechanisms leading to these outcomes are not completely understood. We focused on Vγ2Vδ2 cells, which are part of the immune response against many pathogens, including P. falciparum. These unconventional lymphocytes respond directly to small, nonpeptidic antigens, independent of major histocompatibility complex presentation. We wondered whether placental malaria, which may increase fetal exposure to P. falciparum metabolites, triggers a response by neonatal Vγ2Vδ2 lymphocytes that can be a marker for the extent of fetal exposure to malarial antigens. METHODS: Cord blood mononuclear cells were collected from 15 neonates born to mothers with P. falciparum infection during pregnancy (8 with placental malaria) and 25 unexposed neonates. Vγ2Vδ2 cell phenotype, repertoire, and proliferative responses were compared between newborns exposed and those unexposed to P. falciparum. RESULTS: Placental malaria-exposed neonates had increased proportions of central memory Vγ2Vδ2 cells in cord blood, with an altered Vγ2 chain repertoire ex vivo and after stimulation. CONCLUSION: Our results suggest that placental malaria affects the phenotype and repertoire of neonatal Vγ2Vδ2 lymphocytes. Placental malaria may lower the capacity for subsequent Vγ2Vδ2 cell responses and impair the natural resistance to infectious diseases or the response to pediatric vaccination.

Human cord blood γδ T cells expressing public Vγ2 chains dominate the response to bisphosphonate plus interleukin-15.

Compared with adults, the circulating Vγ2Vδ2 T-cell population in cord blood is present at low levels and does not show the strong bias for Vγ2-Jγ1.2 rearrangements. These features may be a result of limited exposure to stimulatory phosphoantigens, lack of T-cell-derived interleukin-2 (IL-2) or both. In cord blood mononuclear cell cultures, a single round of stimulation, using aminobisphosphonates to elevate phosphoantigen levels, resulted in expansion of adult-like Vγ2 chains and accumulation of memory cells with cytotoxic potential. Selection was similar using IL-2 or myeloid-derived IL-15. The Vγ2Vδ2 T cells present in neonates are capable of generating potent immune responses even when relying on IL-15.

High levels of antibodies to multiple domains and strains of VAR2CSA correlate with the absence of placental malaria in Cameroonian women living in an area of high Plasmodium falciparum transmission.

Placental malaria, caused by sequestration of Plasmodium falciparum-infected erythrocytes in the placenta, is associated with increased risk of maternal morbidity and poor birth outcomes. The parasite antigen VAR2CSA (variant surface antigen 2-chondroitin sulfate A) is expressed on infected erythrocytes and mediates binding to chondroitin sulfate A, initiating inflammation and disrupting homeostasis at the maternal-fetal interface. Although antibodies can prevent sequestration, it is unclear whether parasite clearance is due to antibodies to a single Duffy binding-like (DBL) domain or to an extensive repertoire of antibodies to multiple DBL domains and allelic variants. Accordingly, plasma samples collected longitudinally from pregnant women were screened for naturally acquired antibodies against an extensive panel of VAR2CSA proteins, including 2 to 3 allelic variants for each of 5 different DBL domains. Analyses were performed on plasma samples collected from 3 to 9 months of pregnancy from women living in areas in Cameroon with high and low malaria transmission. The results demonstrate that high antibody levels to multiple VAR2CSA domains, rather than a single domain, were associated with the absence of placental malaria when antibodies were present from early in the second trimester until term. Absence of placental malaria was associated with increasing antibody breadth to different DBL domains and allelic variants in multigravid women. Furthermore, the antibody responses of women in the lower-transmission site had both lower magnitude and lesser breadth than those in the high-transmission site. These data suggest that immunity to placental malaria results from high antibody levels to multiple VAR2CSA domains and allelic variants and that antibody breadth is influenced by malaria transmission intensity.

Circulating soluble endoglin levels in pregnant women in Cameroon and Malawi--associations with placental malaria and fetal growth restriction.

Placental infections with Plasmodium falciparum are associated with fetal growth restriction resulting in low birth weight (LBW). The mechanisms that mediate these effects have yet to be completely described; however, they are likely to involve inflammatory processes and dysregulation of angiogenesis. Soluble endoglin (sEng), a soluble receptor of transforming growth factor (TGF)-ß previously associated with preeclampsia in pregnant women and with severe malaria in children, regulates the immune system and influences angiogenesis. We hypothesized that sEng may play a role in development of LBW associated with placental malaria (PM). Plasma levels of sEng were measured in women (i) followed prospectively throughout pregnancy in Cameroon (n = 52), and (ii) in a case-control study at delivery in Malawi (n = 479). The relationships between sEng levels and gravidity, peripheral and placental parasitemia, gestational age, and adverse outcomes of PM including maternal anemia and LBW were determined. In the longitudinal cohort from Cameroon, 28 of 52 women (54%) experienced at least one malaria infection during pregnancy. In Malawi we enrolled two aparasitemic gravidity-matched controls for every case with PM. sEng levels varied over the course of gestation and were significantly higher in early and late gestation as compared to delivery (P<0.006 and P<0.0001, respectively). Circulating sEng levels were higher in primigravidae than multigravidae from both Cameroon and Malawi, irrespective of malarial infection status (p<0.046 and p<0.001, respectively). Peripheral parasitemia in Cameroonian women and PM in Malawian women were each associated with elevated sEng levels following correction for gestational age and gravidity (p = 0.006 and p = 0.033, respectively). Increased sEng was also associated with the delivery of LBW infants in primigravid Malawian women (p = 0.017); the association was with fetal growth restriction (p = 0.003) but not pre-term delivery (p = 0.286). Increased circulating maternal sEng levels are associated with P. falciparum infection in pregnancy and with fetal growth restriction in primigravidae with PM.

Longitudinal studies of Plasmodium falciparum malaria in pregnant women living in a rural Cameroonian village with high perennial transmission.

A prospective longitudinal study of Plasmodium falciparum in pregnant women was conducted in the rural village of Ngali II, where malaria is hyperendemic and individuals receive ~0.7 infectious mosquito bites/person/day throughout the year. Pregnant women (N = 60; 19 primigravidae, 41 multigravidae) were enrolled early in pregnancy (median 14 wk) and were followed monthly, with 38 women followed through term (5.7 ± 1.1 prenatal visits and delivery). The total number of times primigravidae were slide-positive during pregnancy was higher than multigravidae (3.3 ± 1.1 versus 1.3 ± 1.3 times; P < 0.001), but no difference in the number of polymerase chain reaction-positive cases (4.6 ± 1.7 and 3.4 ± 1.7 times, P = 0.106) or total genotypes they harbored (8.9 ± 3.2 and 7.0 ± 2.9) was found. Only 7.9% women developed symptomatic infections. All primigravidae and 38% multigravidae were placental malaria-positive at delivery (P = 0.009). Genotyping showed that 77% of placental parasites were acquired ≥ 30 wks in pregnancy. These results help identify the extent of malaria-associated changes women experience during pregnancy.

The FIGO working group on the prevention of unsafe abortion: mandate and process for achievement.

The Working Group of the International Federation of Gynecology and Obstetrics (FIGO) on the Prevention of Unsafe Abortion and its Consequences received a mandate to contribute to reduce the number of women who have to resort to induced abortion and the maternal mortality and morbidity associated with unsafe abortion by minimizing unintended pregnancies, improving access to safe abortion services, and increasing the quality of and access to post-abortion care, including post-abortion contraception. A project proposal was prepared and approved by an anonymous donor, funding a structure headed by a general coordinator, the Chair of the Working Group, together with 6 regional coordinators and 1 assistant regional coordinator, plus 43 focal points nominated by the participating societies. A situational analysis of induced/unsafe abortion for each country was prepared by the focal points with the technical support of the Guttmacher Institute, and a plan of action based on the findings of the analysis. The situational analysis and plans of action were discussed at 7 regional workshops held between June and August, 2008. Fifty-four member societies nominated a focal point, 48 attended the regional workshops, and 43 had a plan of action approved by their governments and respective societies. The plans of action are currently in the process of implementation, with the collaboration of a number of national and international agencies and organizations.