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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 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 24–40 weeks; resulting in median CMR of 0.49 to 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.

Summary On Aug 25 2020, the Africa Regional Commission for the Certification of Poliomyelitis Eradication declared that the WHO African region had interrupted transmission of all indigenous wild polioviruses. This declaration marks the African region as the fifth of the six WHO regions to celebrate this extraordinary achievement. Following the Yaounde Declaration on Polio Eradication in Africa by heads of state and governments in 1996, Nelson Mandela launched the Kick Polio out of Africa campaign. In this Health Policy paper, we describe the long and turbulent journey to the certification of the interruption of wild poliovirus transmission, focusing on 2016–20, lessons learned, and the strategies and analyses that convinced the Regional Commission that the African region is free of wild polioviruses. This certification of the WHO African region shows the feasibility of polio eradication in countries with chronic insecurity, inaccessible and hard-to-reach populations, and weak health systems. Challenges have been daunting and the sacrifices enormous—dozens of health workers and volunteers have lost their lives in the pursuit of a polio-free Africa.

Background Malaria remains highly endemic in Cameroon. The rapid emergence and spread of drug resistance was responsible for the change from monotherapies to artemisinin-based combinations. This systematic review and meta-analysis aimed to determine the prevalence and distribution of Plasmodium falciparum drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon from January 1998 to August 2020. Methods The PRISMA-P and PRISMA statements were adopted in the inclusion of studies on single nucleotide polymorphisms (SNPs) of P. falciparum anti-malarial drug resistance genes (Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfatp6, Pfcytb and Pfk13). The heterogeneity of the included studies was evaluated using the Cochran’s Q and I2 statistics. The random effects model was used as standard in the determination of heterogeneity between studies. Results Out of the 902 records screened, 48 studies were included in this aggregated meta-analysis of molecular data. A total of 18,706 SNPs of the anti-malarial drug resistance genes were genotyped from 47,382 samples which yielded a pooled prevalence of 35.4% (95% CI 29.1–42.3%). Between 1998 and 2020, there was significant decline (P Pfcrt 76 T (79.9%-43.0%), Pfmdr1 86Y (82.7%-30.5%), Pfdhfr 51I (72.2%-66.9%), Pfdhfr 59R (76.5%-67.8%), Pfdhfr 108 N (80.8%-67.6%). The only exception was Pfdhps 437G which increased over time (30.4%-46.9%, P Pfdhps 540E that remained largely unchanged (0.0%-0.4%, P = 0.201). Exploring mutant haplotypes, the study observed a significant increase in the prevalence of Pfcrt CVIET mixed quintuple haplotype from 57.1% in 1998 to 57.9% in 2020 (P Pfdhfr IRN mutant haplotype (66.2% to 67.3%, P = 0.427). The Pfk13 amino acid polymorphisms associated with artemisinin resistance were not detected. Conclusions This review reported an overall decline in the prevalence of P. falciparum gene mutations conferring resistance to 4-aminoquinolines and amino alcohols for a period over two decades. Resistance to artemisinins measured by the presence of SNPs in the Pfk13 gene does not seem to be a problem in Cameroon. Systematic review registration PROSPERO CRD42020162620

Background: Cameroon remains a high malaria endemic country. The rapid emergence and spread of Plasmodium falciparum resistant parasites compelled the World Health Organisation (WHO) to recommend the change from monotherapies to artemisinin-based combination therapies (ACTs). This study aimed to assess the clinical efficacy and safety of artemisinin-based combination therapies in the treatment of uncomplicated Plasmodium falciparum malaria in Cameroon from 2004 to 2020.Methods: The preferred reporting items for systematic review and meta-analysis (PRISMA) statement were adopted for the selection of studies. The heterogeneity of the included studies was determined using Cochrane Q and the I2. The random effects model was used as standard to combine studies showing heterogeneity of Cochrane Q with P < 0.10 and I2 > 50.Results: Out of the 4,920 articles and unpublished datasets screened, 16 records with a sample size of 3,737 participants on 8 generic ACTs fulfilled the inclusion criteria. The per protocol (PP) analysis pooled efficacy of the ACTs was 97.9 % (95 % CI, 97.2-98.7, P-group analyses were performed for ASAQ, AL and DHAP. The aggregated efficacies of ASAQ, AL and DHAP were 97.5 % (95 % CI, 96.3-98.8, P-100.0, P=0.39), 98.0 % (95 % CI, 96.3-99.7, P=0.28) respectively. The pooled efficacies were above the WHO minimum benchmark of 90.0%. The ACTs are well tolerated and common adverse events reported were asthenia, diarrhoea, abdominal pain, anorexia, nausea and vomiting, headache and dizziness.Conclusion: This study reported a high pooled efficacy for all ACTs. AL and DHAP were found to have higher cumulative efficacies than ASAQ. The ACTs are still efficacious and well tolerated for the treatment of malaria in Cameroon. However, there is need for continuous monitoring of efficacy of ACTs despite the high cure rates as resistance seems inevitable.

Background: Cameroon remains a country faced with high malaria burden despite enormous efforts made in the control of the disease. The rapid development and dispersal of mutations associated with anti-malarial drug resistance influenced policy changes from the use of chloroquine, amodiaquine and sulphadoxine-pyrimethamine to the adoption of artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated falciparum malaria. However, the impact of drug policy changes on the evolution of molecular markers of Plasmodium falciparum resistance in Cameroon has not been completely understood. Hence, this systematic review and meta-analysis aims to determine the prevalence and distribution of P. falciparum drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon from 1998 to present.Methods: The PRISMA, PRISMA-P and STREGA statements will be adopted in the quality assessments of studies to be included in this review. The electronic databases of Medline via Pubmed, EMBASE, Google Scholar and Science Direct will be searched by two independent researchers using different MeSH terms and Boolean operators (AND, OR). More so, unpublished data that will be sourced from academic libraries will also be extracted. Quantitative syntheses will be done using the “metaphor” and “meta” commands in the R statistical software package version 3.5.2. Heterogeneity will be assessed using the Cochran’s Q and I2 statistics. The random effects model will be used as standard in the determination of heterogeneity between studies. Discussion: The primary outcome of this review is to identify and describe molecular markers conferring drug resistance in Plasmodium falciparum parasites that have been circulating for a period of over 20 years in Cameroon. This review will be able to pool data from previously published and unpublished studies on anti-malarial drug resistance gene mutations. This will provide evidence to support the continuous use of ACTs in the treatment of uncomplicated P. falciparum malaria. Furthermore, data generated from the study will be used as baseline information for the design and adoption of a robust anti-malarial drug resistance surveillance system nationwide which is inexistent. Systematic review registration: PROSPERO CRD42020162620

Background This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to infected Anophelines in Minkoameyos, a rural community in southern forested Cameroon. Methods Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved by screening the doors and windows, installing plywood ceilings on open eaves and closing holes on walls and doors. Monthly entomological surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled from night collections on human volunteers were identified morphologically and their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA and the average entomological inoculation rates determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE = RFI/RFN) measured the true effect of the intervention. Chi square test was used to determine variable significance. The threshold for statistical significance was set at P Results A total of 1113 mosquitoes were collected comprising Anopheles sp (58.6%), Culex sp (36.4%), Aedes sp (2.5%), Mansonia sp (2.4%) and Coquillettidia sp (0.2%). Amongst the Anophelines were Anopheles gambiae sensu lato (s.l.) (95.2%), Anopheles funestus (2.9%), Anopheles ziemanni (0.2%), Anopheles brohieri (1.2%) and Anopheles paludis (0.5%). Anopheles gambiae sensu stricto (s.s.) was the only An. gambiae sibling species found. The intervention reduced the indoor Anopheles density by 1.8-fold (RFI = 3.99; RFN = 2.21; P = 0.001). The indoor density of parous Anopheles was reduced by 1.7-fold (RFI = 3.99; RFN = 2.21; P = 0.04) and that of infected Anopheles by 1.8-fold (RFI = 3.26; RFN = 1.78; P = 0.04). Indoor peak biting rates were observed between 02 a.m. to 04 a.m. in non-improved houses and from 02 a.m. to 06 a.m. in improved houses. Conclusion Housing improvement contributed to reducing indoor residual anopheline density and malaria transmission. This highlights the need for policy specialists to further evaluate and promote aspects of house design as a complementary control tool that could reduce indoor human–vector contact and malaria transmission in similar epidemiological settings.

Characterization of microbial communities in the skin in healthy individuals and diseased patients holds valuable information for understanding pathogenesis of skin diseases and as a source for developing novel therapies. Notably, resources regarding skin microbiome are limited in developing countries where skin disorders from infectious diseases are extremely common. A simple method for sample collection and processing for skin microbiome studies in such countries is crucial. The aim of this study is to confirm the feasibility of collecting skin microbiota from individuals in Yaounde, a capital city of Cameroon, and subsequent extraction of bacterial DNA in a resource limited setting. Skin swabs from several individuals in Yaounde were successfully obtained, and sufficient amount of bacterial 16S ribosomal RNA-coding DNA was collected, which was confirmed by quantitative PCR. The median copy number of 16S ribosomal RNA gene varied across participants and collection sites, with significantly more copies in samples collected from the forehead compared to the left and right forearm, or back. This study demonstrated that collecting surface skin microbes using our swabbing method is feasible in a developing country. We further showed that even with limited resources, we could collect sufficient amount of skin microbiota from the inhabitants in Yaounde where no studies of skin microbiome were reported, which can be passed to further metagenomic analysis such as next generation sequencing.

The coronavirus 2019 (COVID-19) pandemic is challenging the resilience of the most solid health systems in the world. In many low-income and middle-income countries (LMICs), the disease is rapidly spreading amid numerous endemic health problems such as HIV, tuberculosis, malaria, malnutrition, and frequent outbreaks of viral infections with high associated mortality. All this occurs in a context of weak health infrastructures that can barely cope with the aforementioned existing health challenges.

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.

Pregnant women are one of the most susceptible and vulnerable groups to malaria, the most important parasitic disease worldwide. Artemisinin-based combination therapies (ACTs) are recommended for the treatment of uncomplicated malaria in all population groups including pregnant women. However, due to the embryotoxicity observed in animal studies, ACTs have long been contraindicated during the first trimester in pregnant women. Despite the safety concerns raised in pre-clinical studies, recent findings on ACTs's use in pregnant women appear to be reassuring regarding safety and have prompted a revision of malaria treatment guidelines for first trimester of pregnancy. To contribute to the risk-benefit assessment of ACTs, we conducted a systematic literature review of animal studies published between 2007 and 2019, which evaluated the embryotoxic effects of artemisinin and its derivatives among pregnant mammals. Eighteen experimental studies fitted the inclusion criteria. These studies confirmed and further characterized the severe embryolethal and embryotoxic dose-dependent effects of artemisinin and its derivatives when administered during the organogenesis period in rats, rabbits and monkeys. Timing of administration and dosage of the drug were found to be key factors in the appearance of embryo damage. Overall, the translation of the findings of artemisinin derivatives use in animal studies to pregnant women remains disturbing. Thus, a policy change in the use of ACTs during the first trimester in pregnant women for the treatment of uncomplicated malaria does not seem pertinent and if implemented, it should be accompanied by solid pharmacovigilance systems, which are challenging to establish in malaria endemic countries.

Background: COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite the World Health Organization’s publication of different measures to curb the spread of COVID-19, new cases are reported daily. These protective control measures put in place assumed that transmission of COVID-19 was mediated essentially through droplets released from the nasal and respiratory secretions of infected persons. Recent scientific evidence however puts forward the occurrence and shedding of active COVID-19 virus in stools of infected persons. The present study tested the acceptability of an improved version of the ‘Yellow soup’ which contains ingredients/spices with known antibacterial/antiviral properties. Methods : Star Yellow was made by using a palm oil/limestone base to which was added spices /ingredients rich in zinc and known for their antiviral/antibacterial activity. Sensory evaluation of the resulting mixture was done by a taste panel comprising habitual eaters of ‘Yellow soup’ using a hedonic scale of 1 to 5. Results and Conclusion : Sensory assessment of Star Yellow showed a mean acceptability of 77.4% compared to 54.8% obtained for the commercial Yellow Soup served in restaurants. This indicates the acceptable taste of Star Yellow and opens up potential new avenues of research in the control of SARS-CoV-2 virus transmission via feces. Keywords : Yellow soup, COVID-19, feces, gastrointestinal tract, zinc, RNA replication.

Plasmodium falciparum infections are serious in pregnant women, because VAR2CSA allows parasitized erythrocytes to sequester in the placenta, causing placental malaria (PM). In areas of endemicity, women have substantial malarial immunity prior to pregnancy, including antibodies to merozoite antigens, but produce antibodies to VAR2CSA only during pregnancy. The current study sought to determine the importance of antibodies to VAR2CSA and merozoite antigens in pregnant women in Yaounde, Cameroon, where malaria transmission was relatively low. A total of 1,377 archival plasma samples collected at delivery were selected (at a 1:3 ratio of PM-positive [PM+] to PM-negative [PM−] women) and screened for antibodies to full-length VAR2CSA and 7 merozoite antigens. Results showed that many PM+ women and most PM− women lacked antibodies to VAR2CSA at delivery. Among PM+ women, antibodies to VAR2CSA were associated with a reduced risk of having high placental parasitemia (odds ratio [OR], 0.432; confidence interval [CI], 0.272, 0.687; P = 0.0004) and low-birth-weight (LBW) babies (OR = 0.444; CI, 0.247, 0.799; P = 0.0068), even during first pregnancies. Among antibodies to the 7 merozoite antigens, i.e., AMA1, EBA-175, MSP1 42 , MSP2, MSP3, MSP11, and Pf41, only antibodies to MSP3, EBA-175, and Pf41 were associated with reduced risk for high placental parasitemias ( P = 0.0389, 0.0291, and 0.0211, respectively) and antibodies to EBA-175 were associated with reduced risk of premature deliveries ( P = 0.0211). However, after adjusting for multiple comparisons significance declined. Thus, in PM+ women, antibodies to VAR2CSA were associated with lower placental parasitemias and reduced prevalence of LBW babies in this low-transmission setting.

Rose Gana Fomban Leke is an Emeritus Professor of Immunology and Parasitology of the Faculty of Medicine and Biomedical Sciences of the University of Yaounde I, and former director of the Biotechnology Centre of the same university, in Cameroon. She is chair of the Board of Directors of the National Medical Research Institute (IMPM). Rose has served, and still serves, on many committees for the WHO. She is Chair of the African Regional Commission for the Certification of Poliomyelitis Eradication, and a member of the Malaria Policy and Advisory Committee (MPAC).

Background Current malaria diagnostic methods require blood collection, that may be associated with pain and the risk of transmitting blood-borne pathogens, and often create poor compliance when repeated sampling is needed. On the other hand, the collection of saliva is minimally invasive; but saliva has not been widely used for the diagnosis of malaria. The aim of this study was to evaluate the diagnostic performance of saliva collected and stored at room temperature using the OMNIgene®•ORAL kit for diagnosing Plasmodium falciparum malaria. Methods Paired blood and saliva samples were collected from 222 febrile patients in Cameroon. Saliva samples were collected using the OMNIgene®•ORAL (OM-501) kit and stored at room temperature for up to 13 months. Thick blood film microscopy (TFM) was used to detect P. falciparum blood-stage parasites in blood. Detection of P. falciparum DNA in blood and saliva was based on amplification of the multi-copy 18 s rRNA gene using the nested-polymerase chain reaction (nPCR). Results Prevalence of malaria detected by TFM, nPCR-saliva and nPCR-blood was 22, 29, and 35%, respectively. Using TFM as the gold standard, the sensitivity of nPCR-saliva and nPCR-blood in detecting P. falciparum was 95 and 100%, respectively; with corresponding specificities of 93 and 87%. When nPCR-blood was used as gold standard, the sensitivity of nPCR-saliva and microscopy was 82 and 68%, respectively; whereas, the specificity was 99 and 100%, respectively. Nested PCR-saliva had a very good agreement with both TFM (kappa value 0.8) and blood PCR (kappa value 0.8). At parasitaemia > 10,000 parasites/µl of blood, the sensitivity of nPCR-saliva was 100%. Nested PCR-saliva detected 16 sub-microscopic malaria infections. One year after sample collection, P. falciparum DNA was detected in 80% of saliva samples stored at room temperature. Conclusions Saliva can potentially be used as an alternative non-invasive sample for the diagnosis of malaria and the OMNIgene®•ORAL kit is effective at transporting and preserving malaria parasite DNA in saliva at room temperature. The technology described in this study for diagnosis of malaria in resource-limited countries adds on to the armamentarium needed for elimination of malaria.

Objective Mycobacterium tuberculosis isolates that fail to hybridize to at least one rpoB wild-type or any mutation probe on the Genotype MTBDRplus strip are assumed to be rifampicin-resistant. However, the precise mutation(s) are unknown. We sought to identify the mutations in isolates with such hybridization patterns and determine if the mutations are associated with resistance to rifampicin. Methods In this study, 275 M. tuberculosis isolates were screened with the Genotype MTBDRplus assay to identify isolates with the hybridization pattern. These isolates were sequenced and their minimum inhibitory concentrations (MIC) determined using the Bactec MGIT 960 system. Results Among the 275 isolates tested, 15 (6%) isolates with the hybridization pattern were identified. Sequencing showed that failure to hybridize to rpoB wild-type probes resulted from the presence of ‘disputed' rifampicin mutations, which are mutations not always associated with a rifampicin-resistant phenotype. All, except 3/15, isolates had a rifampicin-resistant phenotype (MIC > 1 μg/mL). One of the three isolates with a rifampicin-susceptible phenotype had the same mutation at position 526 (His526Leu) as another isolate that had a rifampicin-resistant phenotype. Conclusion The recommendation of the Genotype MTBDRplus assay to assume rifampicin resistance based solely on failure to hybridize to rpoB wild-type probe allows the identification of important RIF-resistant isolates. About 20% (3/15) of such isolates could be missed by relying only on the standard MGIT 960 DST assay for drug susceptibility testing.

Background Diagnosis of Plasmodium falciparum is often based on detection of histidine-rich protein 2 (HRP2) in blood. Most HRP2-based assays have high sensitivity and specificity; however, authors have suggested that antibodies (Ab) to HRP2 could reduce assay sensitivity. This study sought to characterize the antibody response to HRP2 with respect to prevalence, class, subclass, affinity, and age distribution in Cameroonian children and adults residing in an area with high P. falciparum transmission. Methods Plasma samples from 181 Cameroonian children and adults who had been repeatedly exposed to P. falciparum and 112 samples from American adults who had never been exposed were tested for IgG Ab to HRP2. For comparison, Ab to the merozoite antigens MSP1, MSP2, MSP3 and the pregnancy-associated antigen VAR2CSA were measured using a multiplex bead-based assay. In addition, 81 plasma samples from slide-positive individuals were screened for IgM Ab to HRP2. Results As expected, children and adults had IgG Ab to MSP1, MSP2 and MSP3, antibody levels increased with age, and only women of child-bearing age had Ab to VAR2CSA; however, no convincing evidence was found that these individuals had an acquired antibody response to HRP2. That is, using two sources of recombinant HRP2, identical results were obtained when plasma from 110 Cameroonian adults and 112 US adults were screened for IgG Ab. Further studies showed that antibody prevalence and levels did not increase with age in Cameroonians between ages 5 and >80 years. Although a few samples from slide-positive Cameroonians had IgM values slightly above the American cut-off, it was unclear if the individuals had a true IgM response to HRP2 or if the values were due to non-specific binding from elevated immunoglobulin levels associated with infection. Data from prediction models showed a paucity of Class II T cell epitopes in HRP2. Conclusions These data support the conclusion that most individuals in malaria-endemic areas do not produce an acquired humoral response to HRP2. The absence of Ab helps explain why HRP2-based assays are able to detect nanogram amounts of HRP2 and why HRP2 continues to circulate for a long time after parasite clearance.

Although mother-to-child transmission of HIV has dramatically declined, the number of in utero HIV-exposed, uninfected infants is on the increase. HIV-exposed infants are at an increased risk of mortality, morbidity and slower early growth than their non-HIV exposed counterparts. Maternal HIV increases the risk of having preterm deliveries, intrauterine growth restriction and low birth weight babies. However, the mechanism underlying dysregulation of fetal growth in HIV-infected pregnant women is unknown. We sought to determine whether maternal HIV is associated with dysregulation of the insulin-like growth factor (IGF) axis, some angiogenic factors or other related biomarkers that regulate fetal growth. A total of 102 normotensive pregnant women were enrolled in a small cross-sectional study. Amongst these were thirty-one HIV-1 positive women receiving combination antiretroviral therapy (cART) (Mean age: 30.0 ± 5.1 years; % on ART: 83.9%; median plasma viral load: 683 copies/ml; median CD4 count: 350 cells/ul) and 71 HIV uninfected women (mean age: 27.3 ± 5.8) recruited at delivery. A panel of biomarkers including IGF1 and IGF binding proteins (IGFBP1, IGFBP3), angiopoietins (ANG) 1 and 2, matrix metalloproteinases (MMP) 2 and 9, and galectin 13, was measured in plasma collected from the placental intervillous space. The levels of IGF1, IGFBP1, ANG1, ANG2, MMP2, MMP9 and Gal-13 were not affected by maternal HIV, even when adjusted for maternal factors in linear regression models (all p>0.05). It was observed that HIV-infection in pregnancy did not significantly affect key markers of the IGF axis and angiogenic factors. If anything, it did not affect women. These findings highlight the importance of the use of ART during pregnancy, which maintains factors necessary for fetal development closer to those of healthy women. However, decrease in IGF1 levels might be exacerbated in women con-infected with HIV and malaria.

BackgroundImmunoglobulin G (IgG)-specific responses against Plasmodium falciparum merozoite antigens such as the merozoite surface protein 3 (MSP3) and UBO5 are known to play critical roles in parasitaemia control and protection from symptomatic illness. However, when there is intense perennial malaria transmission coupled with concurrent infection with the human immunodeficiency virus type 1 (HIV), knowledge of IgG antibody response profiles is limited.In this study we assessed the impact of dual HIV/malaria infections on IgG subclass responses to MSP3 (QβMSP3) and UBO5 (QβUB05) in individuals living in two areas of Cameroon differing in malaria transmission intensity.MethodsIgG and IgG subclass responses specific to either MSP3 or UBO5 were determined in plasma from study participant by ELISA. To improve reactivity with their respective antibodies the antigens were displayed upon the surface of the RNA coliphage Qβ.ResultsWe observed differences in antigen-specific IgG and IgG subclass responses which were dependent upon the antigen type, malaria transmission intensity, HIV infection, malaria infection and dual HIV/malaria infections. Individuals living in areas with high malaria transmission, had irrespective of HIV or malaria status significantly higher IgG responses to both antigens (p=0.0001 for QβMSP3, p=0.0001 for QβUB05) than their counterpart from areas with low transmission. When dual HIV/malaria infection is considered, significantly higher QβMSP3 specific IgG1 (p=0.0001) and IgG3 (p=0.04) responses in double-negative individuals was associated with protection against malaria in areas with low transmission. Superior QβUBO5 specific IgG1 responses (p=0.0001) in double-negative individuals were associated with protection in areas with high transmission in contrast to significantly higher IgG3 responses to QβUBO5 (p=0.0001) which were more relevant to protection in areas with low malaria transmission in the same population.ConclusionThus, understanding immune responses to QβUBO5 and QβMSP3 could facilitate the development of immunotherapeutic strategies suitable for areas differing in malaria transmission intensity.

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 V gamma 2V delta 2 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 V gamma 2V delta 2 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. V gamma 2V delta 2cell 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 V gamma 2V delta 2 cells in cord blood, with an altered V?2 chain repertoire ex vivo and after stimulation. Conclusion. Our results suggest that placental malaria affects the phenotype and repertoire of neonatal V gamma 2V delta 2 lymphocytes. Placental malaria may lower the capacity for subsequent V gamma 2V delta 2 cell responses and impair the natural resistance to infectious diseases or the response to pediatric vaccination.

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.

Attracting and retaining women in health research is crucial as it will maximize creativity and innovation as well as increase gender competency and expertise in the field. To help address the gender gap in the research for health field in Cameroon, some women research scientists formed the Higher Institute for Growth in HEalth Research for Women (HIGHER Women) consortium to support and encourage the growth of women research scientists through a training institute with a Mentor–Protégé Program (MPP). The consortium set up a MPP aiming at providing professional guidance to facilitate protégés' growth and emergence in health research. The consortium has conducted two workshops aiming at increasing the early-career women's skills needed to launch their career and focusing on proposal writing with the aim of producing a fundable project. Since 2015, the consortium has brought together approximately 100 women comprising of 80 protégés. The most significant outcome is in the protégés' feedback from their annual evaluations. The protégés are now more likely to submit abstracts and attend international conferences. Some grants have been obtained as a result of the working relationship with mentors. The HIGHER women consortium works to develop a pipeline of women leaders in health research by fostering growth and leadership culture through their MPP.

Background Antigenic variation of Plasmodium falciparum erythrocyte membrane protein 1 is a key parasite mechanism for immune evasion and parasite survival. It is assumed that the number of parasites expressing the same var gene must reach high enough numbers before the host can produce detectable levels of antibodies (Ab) to the variant. VAR2CSA is a protein coded for by one of 60 var genes that is expressed on the surface of infected erythrocytes (IE) and mediates IE binding to the placenta. The idea that Ab to VAR2CSA are pregnancy-associated was challenged when VAR2CSA-specific Ab were reported in children and men. However, the frequency and conditions under which Ab to VAR2CSA are produced outside pregnancy is unclear. This study sought to determine frequency, specificity and level of Ab to VAR2CSA produced in children and whether children with hyperparasitaemia and severe malaria are more likely to produce Ab to VAR2CSA compared to healthy children. Methods Antibody responses to a panel of recombinant proteins consisting of multiple VAR2CSA Duffy-binding-like domains (DBL) and full-length VAR2CSA (FV2) were characterized in 193 1–15 year old children from rural Cameroonian villages and 160 children with severe malaria from the city. Results Low Ab levels to VAR2CSA were detected in children; however, Ab levels to FV2 in teenagers were rare. Children preferentially recognized DBL2 (56–70%) and DBL4 (50–60%), while multigravidae produced high levels of IgG to DBL3, DBL5 and FV2. Sixty-seven percent of teenage girls (n = 16/24) recognized ID1–ID2a region of VAR2CSA. Children with severe forms of malaria had significantly higher IgG to merozoite antigens (all p 0.05) when compared to the healthy children. Conclusion The study suggests that children, including teenage girls acquire Ab to VAR2CSA domains and FV2, but Ab levels are much lower than those needed to protect women from placental infections and repertoire of Ab responses to DBL domains is different from those in pregnant women. Interestingly, children with severe malaria did not have higher Ab levels to VAR2CSA compared to healthy children. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1585-y) contains supplementary material, which is available to authorized users.

Background. During pregnancy, the placenta is inaccessible for diagnosis of placental malaria (PM), but soluble tumor necrosis factor-α receptors (sTNFR) are elevated in the plasma of women with PM. Methods. In this study, sTNFR-1 and sTNFR-2 were quantified in urine of pregnant and nonpregnant Cameroonian women who were positive or negative for malaria by blood-smear microscopy. Results. We found that levels of both sTNFR in urine were higher in pregnant compared with nonpregnant women, but malaria-positive pregnant women excreted substantially more sTNFR-1 (P = .005) and sTNFR-2 (P < .001) than malaria-negative pregnant women. The amount of sTNFR-1(rs = 0.784, P < .001) and sTNFR-2 (rs = 0.816, P < .001) in urine correlated with parasitemia, even in afebrile pregnant women. Urine sTNFR-2 predicted maternal malaria with an area under curve of 0.892 (95% confidence interval, .787–.898). At cutoff concentrations of 9.8 ng and 13.6 ng of sTNFR-2 per mL urine, the sensitivity/specificity were 82.6%/87.0% and 78.3%/95.7%, respectively. Conclusions. The sTNFR-2 in noninvasive urine samples may be useful for diagnosis of malaria during pregnancy.

Background. Human immunodeficiency virus (HIV) infection reduces placental transfer of antibodies from mother to the fetus for many antigens; however, conflicting data exist for transfer of immunoglobulin G (IgG) to malarial antigens. The mechanism(s) underlying reduced placental transfer is unknown. Methods. Levels of maternal and cord total IgG, IgG subclasses, and cord-to-mother ratios (CMRs) were measured in 107 mother-cord pairs to 3 malarial antigens: circumsporozoite protein (CSP), apical membrane antigen 1 (AMA-1), merozoite surface protein 1 (MSP-1), and tetanus toxoid C-fragment (TTc). Results. Immunoglobulin G levels to CSP and TTc were lower in HIV+ mothers, and cord IgG to CSP, MSP-1, and TTc were significantly lower in neonates born to HIV+ mothers (all P values Conclusions. Data confirmed that HIV infections are associated with lower cord antibody levels to malarial antigens and that hypergammaglobulinemia may contribute to reduced antibody transfer.

Anti-vector intervention remains the most effective way of controlling malaria. Although in Cameroon and elsewhere focus is on the use of long-lasting insecticidal nets and indoor residual spraying, the efficacy of both methods greatly depends on the continuing susceptibility of the vectors to the insecticides used. The emergence and spread of insecticide resistance in the major malaria vectors constitute a huge challenge to control programmes. Consequently, routine monitoring and evaluation of vector resistance status to insecticides are mandatory for early detection of resistance should it arise, and effectively planning future anti-vector interventions especially in areas reputed for routine application in agriculture. The WHO bioassay kit was used to determine the susceptibility status of Anopheles gambiae s.l. populations to seven insecticides belonging to four classes (organochlorine, organophosphate, carbamate and pyrethroids) in Niete, an area of intense rubber cultivation in southern forested Cameroon. Species and molecular forms of An. gambiae s.l. as well as the presence of knock down resistance (kdr) mutations were determined using polymerase chain reaction (PCR) techniques. All Anopheles tested was identified as An. gambiae s.s. and of the M molecular form. Based on WHO classification, while the mosquitoes were fully (100%) susceptible to malathion and bendiocarb, resistance was confirmed to DDT and the pyrethroids, permethrin and lambda-cyhalothrin. The other pyrethroids (deltamethrin and cyfluthrin) showed signs of developing resistance. Resistance to DDT and pyrethroids is indicative of existing cross resistance mechanisms between these insecticides. The increase in knockdown times was greater than twofold that of the reference susceptible strain, suggesting the possible involvement of kdr mutations, also confirmed in this study. The findings highlight the need for constant evaluation, re-evaluation and monitoring of the insecticides for malaria vector control in Cameroon. However, bendiocarb and malathion can be used and may require alternation or combination with insecticides of other classes to better manage the occurrence and spread of resistance in Niete.

Le paludisme demeure la premiere cause de morbidite et de mortalite au Cameroun. L'objectif de cette etude est de determiner la composition en carotenoides, vitamine A et vitamine E, nutriments importants pour le fonctionnement du systeme immunitaire, des aliments consommes par les populations d'une zone rurale de paludisme endemique au Cameroun (Ngali II). Les aliments couramment consommes a Ngali II sont constitues de: sauces legeres preparees a partir de legumineuses ou de Cucurbitacees ; sauces epaisses preparees a partir des legumes-feuilles verts ; pâtes preparees a partir de legumineuses, de Cucurbitacees ou du manioc ; grains ; differents tubercules et plantain. Les aliments ont ete analyses par Chromatographie Liquide Haute Performance. Les resultats sont exprimes en microgramme pour 100 grammes de matiere seche : α-carotene 0-6434,7; β-carotene 0-15612,5; vitamine A 0-1442,4; vitamine E 0-40776. Les aliments du groupe 4 presentent les teneurs les plus elevees en nutriments: 3 808,52; 8 722,50; 1 761,65 et 18 048 microgrammes pour 100 g de matiere seche respectivement pour le α-carotene, le β-carotene, la vitamine A et la vitamine E. Ainsi une consommation accrue des aliments de ce groupe permettrait aux populations de mieux resister a diverses pathologies infectieuses comme le paludisme.

Natural populations of Anopheles gambiae s.s. M form and An. melas were assessed for susceptibility to pyrethroid (deltamethrin and permethrin), DDT and carbosulfan insecticides in three localities in coastal Cameroon. Anopheles melas was recorded only from Limbe and Idenau localities, with all samples susceptible to the four insecticides. Anopheles gambiae M form from all three villages was 100 % susceptible to deltamethrin and permethrin, but showed 6.3 % survival on 4 % DDT in Tiko village. Resistance in An. gambiae M form to carbosulfan was found at all three sites, with mortality rates ranging from 53 to 90 %. These findings provide a baseline for evidence-based planning and implementation of malaria vector control activities in the surveyed areas and can be used for comparison in vector control monitoring activities.

Plasmodium falciparum infection during pregnancy can lead to the transplacental passage of malarial Ags that are capable of inducing acquired immune responses in the fetus. Studies have identified cytokines produced by malaria-specific cord blood (CB) T cells, but information on fetal B cells is limited. Thus, CB mononuclear cells from 120 Cameroonian newborns were cultured for 7 days in vitro and supernatants were assessed by ELISA for Abs to an extract of malarial schizonts (MA), recombinant apical merozoite Ag 1 (AMA-1), the 42-kDa C-terminal region of merozoite surface protein 1 (MSP-142), a B epitope of ring-infected erythrocyte surface Ag (RESA), and the dominant B epitope of the circumsporozoite protein (CSP). Only 12% of supernatants contained IgM to MA but 78% had IgG to one or more malarial Ags, with 53% having IgG to AMA-1, 38% to MSP-142, 3% to RESA, and 0% to CSP. The Abs to AMA-1 and MSP-142 were predominantly IgG1 and IgG3. CB mononuclear cells were also tested for the ability to secrete cytokines in response to MA and a pool of conserved MSP-1 T cell epitopes. Among the Ag-reactive samples, 39.3% produced only Th2-type cytokines, whereas 60.6% produced a combination of Th1- and Th2-type cytokines. Although a Th2 bias was observed, the in utero cytokine environment was adequate to support isotype switching to cytophilic IgGs, the isotypes that are protective in adults. Because many infants living in a low transmission area are born with malaria-specific B and T cells, the influence of in utero priming on neonatal immunity merits further investigation.

Background All suspected cases of malaria should receive a diagnostic test prior to treatment with artemisinin-based combinations based on the new WHO malaria treatment guidelines. This study compared the accuracy and some operational characteristics of 22 different immunochromatographic antigen capture point-of- malaria tests (RDTs) in Cameroon to inform test procurement prior to deployment of artemisinin-based combinations for malaria treatment. Methods One hundred human blood samples (50 positive and 50 negative) collected from consenting febrile patients in two health centres at Yaoundé were used for evaluation of the 22 RDTs categorized as “Pf Only” (9) or “Pf + PAN” (13) based on parasite antigen captured [histidine rich protein II (HRP2) or lactate dehydrogenase (pLDH) or aldolase]. RDTs were coded to blind technicians performing the tests. The sensitivity, specificity, and predictive values of the positive and negative tests (PPV and NPV) as well as the likelihood ratios were assessed. The reliability and some operational characteristics were determined as the mean values from two assessors, and the Cohen’s kappa statistic was then used to compare agreement. Light microscopy was the referent. Results Of all RDTs tested, 94.2 % (21/22) had sensitivity values greater than 90 % among which 14 (63.6 %) were ‘Pf + PAN’ RDTs. The specificity was generally lower than the sensitivity for all RDTs and poorer for “Pf Only” RDTs. The predictive values and likelihood ratios were better for non-HRP2 analytes for “Pf + PAN” RDTs. The Kappa value for most of the tests obtained was around 67 % (95 % CI 50–69 %), corresponding to a moderate agreement. Conclusion Overall, 94.2 % (21/22) of RDTs tested had accuracy within the range recommended by the WHO, while one performed poorly, below acceptable levels. Seven “Pf + PAN” and 3 “Pf Only” RDTs were selected for further assessment based on performance characteristics. Harmonizing RDT test presentation and procedures would prevent mistakes of test performance and interpretation. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1085-0) contains supplementary material, which is available to authorized users.

The Malaria Policy Advisory Committee to the World Health Organization held its sixth meeting in Geneva, Switzerland from 10 to 12 September 2014. This article provides a summary of the discussions, conclusions and recommendations from that meeting. Meeting sessions covered the following: an update on drug resistance and containment including an assessment on the feasibility of elimination of Plasmodium falciparum malaria in the Greater Mekong Subregion; guidance on the control of residual malaria transmission by behaviourally resistant vectors; progress on the implementation of the Global Plan for Insecticide Resistance Management; updates on the Global Technical Strategy, Global Malaria Action Plan and the Plasmodium vivax technical brief; gaps in current World Health Organization Global Malaria Programme guidance for acceleration to elimination; surveillance, monitoring and evaluation; the updated World Health Organization Guidelines for the Prevention and Treatment of Malaria; Round 5 product testing for rapid diagnostic tests; and Intermittent Preventive Treatment for infants. Policy statements, position statements, and guidelines that arise from the Malaria Policy Advisory Committee meeting conclusions and recommendations will be formally issued and disseminated to World Health Organization Member States by the World Health Organization Global Malaria Programme.

This study deals with determination of some of the mineral salts and phytate contents in the food consumed by inhabitants of Cameroon known as Ngali II, a rural area, which is a malaria endemic zone. The food consumed by the people of this area are light and thick sauces prepared from several green leafy vegetables, leguminous seeds and cucurbit seeds (egusi seeds), pastes prepared from leguminous seeds or egusi seeds complemented with different tubers and plantains. The mineral salt contents were determined by atomic absorption spectrophotometry and phytate by spectrophotometric methods. The results are expressed in mg (100 g)[superscript [-]1] dry weight. Iron: 1.32-28.46, zinc: 2.0-7.28, copper: 0.13-1.09, magnesium: 24.5-369.8 and phytate: 9.08-1988.2. This study reveals that a high consumption of food rich in zinc will greatly reduce the high prevalence of malaria in Ngali II.

The prevalence of pre-term deliveries (PTDs) is increased in women who become infected with Plasmo- dium falciparum during pregnancy. Because prematurity is a risk factor for newborns, it is important to identify conditions that contribute to malaria-associated PTDs. Plasmodium falciparum−infected erythrocytes sequester in the placenta and attract activated mononuclear cells that secrete pro-inflammatory cytokines. Increased inflammatory cytokine levels in other microbial infections are associated with PTDs. To determine if such is the case in women with placental malaria, concentrations of interferon- (IFN-), tumor necrosis factor- (TNF-), interleukin-4 (IL-4), and IL-10 were measured in placental plasma of 391 malaria-infected and -uninfected Cameroonian women with premature and full-term deliveries. Risk factors for malaria-associated PTDs included peripheral and placental parasitemias greater than 1%, maternal anemia, elevated IL-10 levels, and low TNF-:IL-10 ratios due to over-expression of IL-10. Alter- ations in cytokine levels may contribute to PTDs through the induction of anemia and/oralter ing cellularimmune responses required for eliminating placental parasites.

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.

When a woman is pregnant, especially for the first and second times, she is susceptible to more frequent and severe malaria infections than when she was not pregnant. These infections are associated with maternal anemia, premature deliveries, and low birth weight infants. In areas where malaria is endemic, strategies to control malaria during pregnancy include preventive measures, such as the use of insecticide-treated mosquito nets (ITNs) and intermittent preventive treatment (IPTp), as well as case management as a curative measure. With regard to IPTp in the African Region, the World Health Organization (WHO) recommends 2 or 3 doses of sulfadoxine-pyrimethamine (SP) that are given during the second and third trimesters, at least 1 month apart [1]. This policy has been accepted by most African countries, and SP is delivered at routine antenatal visits. IPTp is being scaled up through reproductive health programs, particularly with funds from the Global Fund for the fight against Tuberculosis, AIDS, and Malaria. Results from other trials have shown that an additional dose of SP adds more benefit over the 2-dose regimen among human immunodeficiency virus (HIV)– infected women who are primiand secundi-gravidae [2]. Thus, the WHO recommends 2 or 3 doses of IPTp SP, with 3 doses being used where the prevalence of HIV infection among women is high. Some countries, such as Cameroon, have selected 3 doses of SP in their policy for all pregnant women, whereas some countries, such as Mali, chose 2 doses. In this issue of the journal, Maiga et al [3] report on a randomized clinical trial performed in Mali, which shows the superiority of 3 over 2 doses of IPTp SP for the prevention of placenta malaria and associated low birth weight infants. Mali, as the authors describe, has highly seasonal malaria transmission, moderate levels of ITN use, and low levels of SP resistance. Mali had adopted a 2-dose strategy in 2003. A survey of 1696 pregnant women during 2005–2007 showed that women who completed IPT SP early during the third trimester had reinfections later during the third trimester, meaning that the 2 doses provided insufficient protection. Therefore, the study reported in this issue was undertaken. Results of this randomized clinical trial clearly showed that adding a third dose of SP halved the risk of placenta malaria and low birth weight in all gravidae, compared with the standard 2-dose regimen. This study has therefore provided evidence that was needed in Mali, to move their policy from 2 to 3 doses. In the study design, the use of ITNs was not considered as a factor, most likely because Mali has moderate levels of ITN use. Studies from Kenya and the Gambia [2] have shown that IPTp SP provides less benefit to pregnant women who are using ITNs. Thus, increased use of ITNs may overcome the need for a third dose of SP, which would result in less use of SP by the population and, consequently, put less drug pressure on the parasite. Increased drug use and its consequence of drug pressure is an important factor that drives the development of drug-resistant parasites. Received 25 April 2011; accepted 29 April 2011. Correspondence: Rose Gana Fomban Leke, PhD, Department of Microbiology, Immunology and Hematology, Faculty of Medicine and Biomedical Sciences, Biotechnology Center, University of Yaounde 1, Yaounde, Cameroon (roseleke@ yahoo.com). Clinical Infectious Diseases 2011;53(3):231–233 The Author 2011. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals. permissions@oup.com. 1058-4838/2011/533-0003$14.00 DOI: 10.1093/cid/cir383

Background Malaria transmission in Cameroon is mediated by a plethora of vectors that are heterogeneously distributed across the country depending on the biotope. To effectively guide malaria control operations, regular update on the role of local Anopheles species is essential. Therefore, an entomological survey was conducted between August 2010 and May 2011 to evaluate the role of the local anopheline population in malaria transmission in three villages of the Ndop health district in the northwest region of Cameroon where malaria is holoendemic, as a means to acquiring evidence based data for improved vector intervention. Methods Mosquitoes were sampled both indoor and outdoor for four consecutive nights in each locality during each month of survey. Sampling was done by the human landing catch method on volunteers. Anopheles species were identified morphologically and their ovaries randomly dissected for parity determination. Infection with Plasmodium falciparum was detected by Circumsporozoite protein ELISA. Members of An. gambiae complex were further identified to molecular level by PCR and RFLP PCR. Results An. ziemanni was the main malaria vector and whether outdoor or indoor. The man biting rate for the vectors ranged from 6.75 to 8.29 bites per person per night (b/p/n). The entomological inoculation rate for this vector species was 0.0278 infectious bites per person per night (ib/p/n) in Mbapishi, 0.034 ib/p/n in Mbafuh, and 0.063 ib/p/n in Backyit. These were by far greater than that for An. gambiae. No difference was observed in the parity rate of these two vectors. PCR analysis revealed the presence of only An. colluzzi (M- form). Conclusions An. ziemanni is an important local malaria vector in Ndop health district. The findings provide useful baseline information on the anopheles species composition, their distribution and role in malaria transmission that would guide the implementation of integrated vector management strategies in the locality.

Otherwise clinically immune women in areas endemic for malaria are highly susceptible to Plasmodium falciparum malaria during their first pregnancy. Pregnancy-associated malaria (PAM) is characterized by placental accumulation of infected erythrocytes that adhere to chondroitin sulfate A (CSA). Susceptibility to PAM decreases with increasing parity, apparently due to acquisition of antibodies directed against the variant surface antigens (VSAs) that mediate the adhesion to CSA (VSA(CSA)). This study found that levels of VSA(CSA)-specific antibodies depend on endemicity, that anti-VSA(CSA) IgG is acquired during gestation week 20, and that plasma levels of the antibodies decline during the postpartum period. There is evidence that VSA(CSA)-specific antibodies are linked to placental infection and that high antibody levels contribute to the control of placental infection by inhibiting parasite adhesion to CSA. Data suggest that VSA(CSA) is a target for vaccination against PAM.

ThePlasmodium falciparumrhoptry-associated proteins 1 and 2 (RAP1 and RAP2) are candidate antigens for a subunit malaria vaccine. The design of the study, which looks at the acquisition of immunity to malaria from childhood to old age, has allowed us to document the interaction of HLA and age on levels of antibody to specific malarial antigens. Antibodies reach maximum levels to RAP1 after the age of 15 but to RAP2 only after the age of 30. The effect of HLA-DRB1 and -DQB1 and age on levels of antibody to rRAP1 and rRAP2 was analyzed with a multiple regression model in which all HLA alleles and age were independent variables. DQB1*0301 and -*03032 showed an age-dependent association with levels of antibody to rRAP1, being significant in children 5 to 15 years (P< 0.001) but not in individuals over 15 years of age. DRB1*03011 showed an age-dependent association with antibody levels to rRAP2; however, this association was in adults over the age of 30 years (P< 0.01) but not in individuals under the age of 30 years. No associations were detected between DRB1 alleles and RAP1 antibody levels or between DQB1 alleles and RAP2 antibody levels. Thus, not only the HLA allele but also the age at which an interaction is manifested varies for different malarial antigens. The interaction may influence either the rate of acquisition of antibody or the final level of antibody acquired by adults.

Placental malaria infections are caused by Plasmodium falciparum–infected red blood cells sequestering in the placenta by binding to chondroitin sulfate A, mediated by VAR2CSA, a variant of the PfEMP1 family of adhesion antigens. Recent studies have shown that many P. falciparum genomes have multiple genes coding for different VAR2CSA proteins, and parasites with >1 var2csa gene appear to be more common in pregnant women with placental malaria than in nonpregnant individuals. We present evidence that, in pregnant women, parasites containing multiple var2csa-type genes possess a selective advantage over parasites with a single var2csa gene. Accumulation of parasites with multiple copies of the var2csa gene during the course of pregnancy was also correlated with the development of antibodies involved in blocking VAR2CSA adhesion. The data suggest that multiplicity of var2csa-type genes enables P. falciparum parasites to persist for a longer period of time during placental infections, probably because of their greater capacity for antigenic variation and evasion of variant-specific immune responses.

Plasmodium falciparum-infected erythrocytes (IEs) sequester in the intervillous space (IVS) of the placenta causing placental malaria (PM), a condition that increases a woman’s chances of having a low-birth-weight baby. Because IEs sequester, they frequently are not observed in peripheral blood smears, resulting in women with PM being misdiagnosed and thus not treated. Because sequestered IEs induce inflammation in the IVS, detection of inflammatory mediators in the peripheral blood may provide an approach for diagnosing PM. Two counterregulatory molecules, TNF-αR (TNFR) 1 and TNFR2, modulate the pathological effects of TNF-α. Levels of these soluble TNFRs (sTNFRs) are reported to be elevated in children with severe malaria, but it is unclear if they are increased in the peripheral blood of PM-positive women with asymptomatic infections. In this study, sTNFR levels were measured throughout the course of pregnancy, as well as at delivery, in women with asymptomatic infections and those who remained uninfected. Results showed that both sTNFRs were significantly increased in the peripheral blood of women with asymptomatic malaria (p < 0.0001) and were positively correlated with parasitemia (p < 0.0001 for sTNFR1 and p = 0.0046 for sTNFR2). Importantly, levels of sTNFR2 were elevated in the peripheral blood of women who were PM-positive but peripheral blood-smear negative (p = 0.0017). Additionally, sTNFR2 levels were elevated in the blood of malaria-positive women who delivered low-birth-weight babies. In vitro studies demonstrated that syncytiotrophoblasts were not a major source of sTNFR. These data suggest that sTNFR2 may be a valuable biomarker for detection of malaria-associated inflammation.

Malarial infections are rarely observed in neonates. It has been postulated that some immunity may be passively transferred during nursing, but anti-malarial antibodies (Abs) have not been detected in human milk. In this study, milk samples, collected 2-14 days after parturition from women at the Central Maternity Hospital, Yaounde, were evaluated for total IgG and IgA antibody levels by radial diffusion, protein composition by SDS-PAGE, anti-malarial antibodies using an isotype-specific immunofluorescence assay, and the ability to immunoprecipitate Plasmodium falciparum antigens metabolically labelled with 35S-methionine. Results showed that anti-P. falciparum antibodies were present in breast milk, and that paired milk and serum samples from individual women contained Abs that recognized similar malarial antigens.

Background Plasmodium falciparum merozoite surface protein-1 (MSP1) has been extensively studied as a blood-stage malaria vaccine candidate, with most work focused on the conserved 19 kDa and semi-conserved 42 kDa C-terminal regions (blocks 16-17) and the hypervariable N-terminal repeat region (block 2). However, recent genotyping studies suggest that additional regions of MSP1 may be under selective pressure, including a locus of intragenic recombination designated as block 4 within the 3' region of the gene. Methods The current study examined the antibody response to the two parental and two recombinant forms of block 4 and to blocks 16-17 (3D7) in study populations from Colombia, Papua New Guinea and Cameroon that differ in malaria transmission intensity and ethnic composition. Results IgM and IgG antibodies were detected against parental and recombinant MSP1 block 4 peptides in all three populations. Overall, 32-44% of the individuals produced IgM to one or more of the peptides, with most individuals having IgM antibodies reactive with both parental and recombinant forms. In contrast, IgG seropositivity to block 4 varied among populations (range 15-65%), with the majority of antibodies showing specificity for one or a pair of block 4 peptides. The IgG response to block 4 was significantly lower than that to blocks 16-17, indicating block 4 is subdominant. Antibodies to block 4 and blocks 16-17 displayed distinct IgG subclass biases, with block 4 responses biased toward IgG3 and blocks 16-17 toward IgG1. These patterns of responsiveness were consistently observed in the three study populations. Conclusions Production of antibodies specific for each parental and recombinant MSP1 block 4 allele in different populations exposed to P. falciparum is consistent with balancing selection of the MSP1 block 4 region by the immune response of individuals in areas of both low and high malaria transmission. MSP1 block 4 determinants may be important in isolate-specific immunity to P. falciparum.

Background Placental malaria (PM) is associated with adverse pregnancy outcomes including low birth weight (LBW). However, the precise mechanisms by which PM induces LBW are poorly defined. Based on the essential role of angiopoietin (ANG)-1 and -2 in normal placental vascular development, we hypothesized that PM may result in the dysregulation of angiopoietins and thereby contribute to LBW outcomes. Methods and Findings In a mouse model of PM, we show that Plasmodium berghei ANKA infection of pregnant mice resulted in dysregulated angiopoietin levels and fetal growth restriction. PM lead to decreased ANG-1, increased ANG-2, and an elevated ratio of ANG-2/ANG-1 in the placenta and the serum. These observations were extended to malaria-exposed pregnant women: In a study of primigravid women prospectively followed over the course of pregnancy, Plasmodium falciparum infection was associated with a decrease in maternal plasma ANG-1 levels (P = 0.031) and an increase in the ANG-2:ANG-1 ratio (P = 0.048). ANG-1 levels recovered with successful treatment of peripheral parasitemia (P = 0.010). In a cross-sectional study of primigravidae at delivery, angiopoietin dysregulation was associated with PM (P = 0.002) and LBW (P = 0.041). Women with PM who delivered LBW infants had increased ANG-2:ANG-1 ratios (P = 0.002) compared to uninfected women delivering normal birth weight infants. Conclusions These data support the hypothesis that dysregulation of angiopoietins is associated with PM and LBW outcomes, and suggest that ANG-1 and ANG-2 levels may be clinically informative biomarkers to identify P. falciparum-infected mothers at risk of LBW deliveries.

During pregnancy, Plasmodium falciparum -infected erythrocytes (IE) sequester in the placenta where they induce pathology and increase the risk of low-birth-weight (LBW) babies. The innate immune mediator, mannose-binding lectin (MBL), enhances phagocytosis of pathogens. Since MBL is reported to bind to IE, we hypothesized that it might aid in clearance of IE from the placenta, thereby reducing the risk of LBW babies. To test this hypothesis, molecular genotyping was used to detect polymorphisms at codon 57 (A/C) in exon 1 of MBL2 in 401 pregnant Cameroonian women, with or without placental malaria, who had LBW and normal-weight babies. Polymorphisms in the promoter region at positions −550 (H/L), −221 (X/Y), and +4 (P/Q) were also determined, and plasma MBL levels were measured during pregnancy and at delivery. The expected correlation between genotype and plasma MBL levels was confirmed. However, asymptomatic infections were not associated with an increase in MBL levels in the peripheral blood, and MBL levels were similar in the placental and cord blood of women with or without placental malaria at delivery. There was no evidence that MBL levels at delivery were associated with malaria-related poor pregnancy outcomes. Women with the LXPA haplotype, however, were more likely to have LBW babies, but the risk was not related to malaria. These results do not support the hypothesis that MBL aids in the clearance of parasites from the placenta but suggest that Cameroonian women with LXPA are at risk of having LBW babies due to other causes.

Background Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas. Methods A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (15 yrs) and followed-up once every three months. Results In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children 15 years, and Plasmodium falciparum was the predominant parasite species. Conclusion Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa.

Placenta-sequestering Plasmodium falciparum involved in the pathogenesis of pregnancy-associated malaria (PAM) in otherwise clinically immune women expresses particular variant surface antigens (VSA PAM ) on the surface of infected erythrocytes that differ from VSA found in parasitized nonpregnant individuals (non-PAM type VSA). We studied levels of immunoglobulin G (IgG) and IgG subclasses with specificity for VSA PAM and for non-PAM type VSA in pregnant and nonpregnant women from two sites with different endemicities in Cameroon. We found that VSA PAM -specific responses depended on the pregnancy status, parity, gestational age, and parasite transmission intensity, whereas only the parasite transmission intensity influenced the levels of IgG specific for non-PAM type VSA. For both types of VSA, the responses were dominated by the cytophilic subclass IgG1, followed by IgG3. In pregnant women, the levels of VSA PAM -specific antibodies either were very low or negative or were very high, whereas the levels of the antibodies specific for non-PAM type VSA were uniformly high. Interestingly, the levels of VSA PAM -specific IgG1 increased with increasing gestational age, while the levels of the corresponding IgG3 tended to decrease with increasing gestational age. The IgG subclass responses with specificity for non-PAM type VSA did not vary significantly with gestational age. Taken together, our data indicate that IgG1 and to a lesser extent IgG3 are the main subclasses involved in acquired VSA PAM -specific immunity to pregnancy-associated malaria.

Because of the life-threatening, post-treatment reactions that have occurred in patients with loiasis treated with ivermectin, evaluation of a short-course albendazole regimen was undertaken in a Loa-endemic region of Cameroon. In a placebo-controlled, double-blinded, crossover study, 99 subjects with microfilaremia (100-3,3837/mL) were assigned to receive albendazole (400 mg; n = 48) or placebo (n = 51) for three days and were followed for 180 days; at day 180, the groups were crossed over and followed for an additional six months. In those initially receiving albendazole (ALB/PLAC), microfilarial levels decreased significantly by day 90 (P < 0.043), but returned to baseline by day 180. In those receiving albendazole at day 180 (PLAC/ALB), microfilarial levels also decreased following albendazole (P = 0.005). Blood eosinophil and antifilarial IgG levels did not change significantly for either group, although antifilarial IgG4 levels did in the ALB/PLAC group at day 180. Most subjects continued to have elevations in microfilaremia, suggesting that more intensive regimens of albendazole will be necessary to reduce Loa microfilaremia to levels safe enough to allow for ivermectin use.