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Genetic diversity of surface exposed and stage specific Plasmodium falciparum immunogenic proteins pose a major roadblock to developing an effective malaria vaccine with broad and long-lasting immunity. We conducted a prospective genetic analysis of candidate antigens (msp1, ama1, rh5, eba175, glurp, celtos, csp, lsa3, Pfsea, trap, conserved chrom3, hyp9, hyp10, phistb, surfin8.2, and surfin14.1) for malaria vaccine development on 2375 P. falciparum sequences from 16 African countries. We described signatures of balancing selection inferred from positive values of Tajima’s D for all antigens across all populations except for glurp. This could be as a result of immune selection on these antigens as positive Tajima’s D values mapped to regions with putative immune epitopes. A less diverse phistb antigen was characterised with a transmembrane domain, glycophosphatidyl anchors between the N and C- terminals, and surface epitopes that could be targets of immune recognition. This study demonstrates the value of population genetic and immunoinformatic analysis for identifying and characterising new putative vaccine candidates towards improving strain transcending immunity, and vaccine efficacy across all endemic populations.

Background Malaria remains a significant health challenge in sub-Saharan Africa, with early diagnosis critical to reducing its morbidity and mortality. Despite the increasing Plasmodium spp. diagnostic capabilities, access to testing is limited in some cases by the almost absolute requirement for blood from potentially infected subjects as the only sample source for all conventional methods. A rapid test on non-invasive specimen with comparable performance to microscopy for the screening or diagnosis of all participants is invaluable. This study sought to compare conventional and non-invasive diagnostic tools for detecting Plasmodium falciparum. Methods This was a cross-sectional study, carried out between March and August 2019 to evaluate and compare the diagnostic performance of a PfHRP2/pLDH-based malaria rapid diagnostic test (mRDT) on patients’ blood, saliva and urine relative to conventional light microscopy and nested PCR at outpatient clinics in the Buea and Tiko health districts of Southwestern Cameroon. The significance of differences in proportions was explored using the Pearson’s χ2 test whereas differences in group means were assessed using analyses of variance. Results A total of 359 individuals of both sexes, aged 1–92 years, were enrolled into the study. Of the 301 individuals tested by light microscopy and mRDTs on blood, saliva and urine, 84 (27.9%), 81 (26.9%), 87 (28.9%) and 107 (35.5%) respectively were positive. However, only 34.3%, 90.5%, 91.4%, 83.9% and 65.4% febrile, light microscopy and mRDT positives on blood, saliva and urine respectively had P. falciparum infection as confirmed by PCR. The sensitivity and specificity of presumptive diagnosis, light microscopy and mRDT on blood, saliva and urine were 86.9% and 19.7%, 77.8% and 96.1%, 75.8% and 96.6%, 74.5% and 93.1%, and 70.7% and 81.8%, respectively. The agreement between mRDT on saliva (k = 0.696) and microscopy (k = 0.766) compared to PCR was good. Conclusion The study highlighted the low performance of presumptive diagnosis, reinforcing the need for parasitological tests prior to antimalarial therapy. The higher PfHRP2/pLDH mRDT parasite detection rates and sensitivity in saliva compared to urine suggests that the former is a practical adjunct to or alternative worth optimising for the routine diagnosis of malaria. Graphic Abstract Flow chart for diagnosis of P. falciparum infection by light microscopy, rapid diagnostic tests and nested PCR.

MalariaGEN is a data-sharing network that enables groups around the world to work together on the genomic epidemiology of malaria. Here we describe a new release of curated genome variation data on 7,000 Plasmodium falciparum samples from MalariaGEN partner studies in 28 malaria-endemic countries. High-quality genotype calls on 3 million single nucleotide polymorphisms (SNPs) and short indels were produced using a standardised analysis pipeline. Copy number variants associated with drug resistance and structural variants that cause failure of rapid diagnostic tests were also analysed. Almost all samples showed genetic evidence of resistance to at least one antimalarial drug, and some samples from Southeast Asia carried markers of resistance to six commonly-used drugs. Genes expressed during the mosquito stage of the parasite life-cycle are prominent among loci that show strong geographic differentiation. By continuing to enlarge this open data resource we aim to facilitate research into the evolutionary processes affecting malaria control and to accelerate development of the surveillance toolkit required for malaria elimination.

Inferences from genetic association studies rely largely on the definition and description of the underlying populations that highlight their genetic similarities and differences. The clustering of human populations into subgroups (population structure) can significantly confound disease associations. This study investigated the fine-scale genetic structure within Cameroon that may underlie disparities observed with Cameroonian ethnicities in malaria genome-wide association studies in sub-Saharan Africa. Genotype data of 1073 individuals from three regions and three ethnic groups in Cameroon were analyzed using measures of genetic proximity to ascertain fine-scale genetic structure. Model-based clustering revealed distinct ancestral proportions among the Bantu, Semi-Bantu and Foulbe ethnic groups, while haplotype-based coancestry estimation revealed possible longstanding and ongoing sympatric differentiation among individuals of the Foulbe ethnic group, and their Bantu and Semi-Bantu counterparts. A genome scan found strong selection signatures in the HLA gene region, confirming longstanding knowledge of natural selection on this genomic region in African populations following immense disease pressure. Signatures of selection were also observed in the HBB gene cluster, a genomic region known to be under strong balancing selection in sub-Saharan Africa due to its co-evolution with malaria. This study further supports the role of evolution in shaping genomes of Cameroonian populations and reveals fine-scale hierarchical structure among and within Cameroonian ethnicities that may impact genetic association studies in the country.

Ebb and flow of parasite populations The population genetics of the malaria parasite Plasmodium falciparum across Africa is poorly understood but important to know for grasping the risks and dynamics of the spread of drug resistance. Harnessing the power of genomics, Amambua-Ngwa et al. of the Plasmodium Diversity Network Africa found substantial population structure within Africa that is consistent with human and vector population divergence (see the Perspective by Sibley). Specific signatures of selection by antimalarial drugs were detected, along with indications of the effect of colonization and slavery. Furthermore, whole-genome sequencing showed that there is extensive gene flow among the different regions and that Ethiopia has a distinctive population of P. falciparum , which may be indicative of coexistence with another malaria parasite, P. vivax. Science , this issue p. 813 ; see also p. 752

Background: Lack of knowledge of rational use of antimalarial drugs among medicine vendors is a serious problem, notably in areas of intense transmission. These misunderstandings increase the risks of resistance and adverse drug reactions. This study aimed to assess knowledge of malaria and environments wherein medicine vendors dispense antimalarials in the Buea community. Methods: Administration of a community-based cross-sectional survey of a random sample of 140 medicine vendors living within the Buea community occurred between March and June 2017. The survey sought to obtain information from medicine vendors on their general knowledge of malaria as well as their dispensing practices. Statistically significant findings were associated with p ≤ .05. Results: The majority of participants were aware that use of insecticide – treated bed nets (ITNs) and maintenance of a clean environment equate to effective malaria prevention efforts. Alternatively, only one-third of participants correctly attributed the causative organism of malaria to being protozoan. Participants employed within drugstore settings had less knowledge of malaria than their hospital/community counterparts did. A directly proportional relationship existed between the amount of experience that participants had in their respective disciplines with an increased knowledge of malaria overall. Conclusion: These findings reveal fluctuating knowledge of malaria among study participants. Reported antimalarial dispensing practices also warrants room for improvement. Routine monitoring and evaluation to prevent emergence of resistant strains to current efficacious antimalarials remains paramount. Article Type: Original Research

We conducted a genome-wide association study of host resistance to severePlasmodium falciparummalaria in over 17,000 individuals from 11 malaria-endemic countries, undertaking a wide ranging analysis which identifies five replicable associations with genome-wide levels of evidence. Our findings include a newly implicated variant on chromosome 6 associated with risk of cerebral malaria, and the discovery of an erythroid-specific transcription start site underlying the association inATP2B4. Previously reported HLA associations cannot be replicated in this dataset. We estimate substantial heritability of severe malaria (h2~ 23%), of which around 10% is explained by the currently identified associations. Our dataset will provide a major building block for future research on the genetic determinants of disease in these diverse human populations.

Drug resistance is one of the greatest challenges of malaria control programmes, with the monitoring of parasite resistance to artemisinins or to Artemisinin Combination Therapy (ACT) partner drugs critical to elimination efforts. Markers of resistance to a wide panel of antimalarials were assessed in natural parasite populations from southwestern Cameroon. Individuals with asymptomatic parasitaemia or uncomplicated malaria were enrolled through cross-sectional surveys from May 2013 to March 2014 along the slope of mount Cameroon. Plasmodium falciparum malaria parasitaemic blood, screened by light microscopy, was depleted of leucocytes using CF11 cellulose columns and the parasite genotype ascertained by sequencing on the Illumina HiSeq platform. A total of 259 participants were enrolled in this study from three different altitudes. While some alleles associated with drug resistance in pfdhfr, pfmdr1 and pfcrt were highly prevalent, less than 3% of all samples carried mutations in the pfkelch13 gene, none of which were amongst those associated with slow artemisinin parasite clearance rates in Southeast Asia. The most prevalent haplotypes were triple mutants Pfdhfr I 51 R 59 N 108 I 164(99%), pfcrt- C72V73 I 74 E 75 T 76 (47.3%), and single mutants PfdhpsS436 G 437K540A581A613(69%) and Pfmdr1 N86 F 184D1246 (53.2%). The predominance of the Pf pfcrt CVIET and Pf dhfr IRN triple mutant parasites and absence of pfkelch13 resistance alleles suggest that the amodiaquine and pyrimethamine components of AS-AQ and SP may no longer be effective in their role while chloroquine resistance still persists in southwestern Cameroon.

Elucidating the evolutionary history and interrelatedness of human-infective Plasmodium species has been hampered by a lack of genetic information for three human-infective species: P. malariae and two P. ovale species (P. o. curtisi and P. o. wallikeri) . These species are prevalent across most malaria endemic regions 2,3 and are often undetectable by light microscopy, making their study in human populations difficult. The exact evolutionary relationship of these species to the other human-infective species has been contested. Using a new reference genome for P. malariae as well as a manually curated draft P. o. curtisi genome, we are now able to accurately place these species within the Plasmodium phylogeny. Sequencing of a chimpanzee-infective P. malariae relative reveals similar signatures of selection in the P. malariae lineage to another Plasmodium lineage where colonisation of both human and chimpanzee hosts has occurred. Molecular dating suggests that these host adaptations occurred over similar evolutionary timescales. In addition to the core genome that is conserved between species, differences in gene content can be linked to their specific biology. The genome suggests that P. malariae expresses a novel family of heterodimeric proteins on its surface that have structural similarities to a protein crucial for red blood cell invasion. The data presented here provide an essential foundation into understanding the evolution of the Plasmodium genus as a whole.

Many human genetic associations with resistance to malaria have been reported, but few have been reliably replicated. We collected data on 11,890 cases of severe malaria due to Plasmodium falciparum and 17,441 controls from 12 locations in Africa, Asia and Oceania. We tested 55 SNPs in 27 loci previously reported to associate with severe malaria. There was evidence of association at P < 1 × 10(-4) with the HBB, ABO, ATP2B4, G6PD and CD40LG loci, but previously reported associations at 22 other loci did not replicate in the multicenter analysis. The large sample size made it possible to identify authentic genetic effects that are heterogeneous across populations or phenotypes, with a striking example being the main African form of G6PD deficiency, which reduced the risk of cerebral malaria but increased the risk of severe malarial anemia. The finding that G6PD deficiency has opposing effects on different fatal complications of P. falciparum infection indicates that the evolutionary origins of this common human genetic disorder are more complex than previously supposed.

INTRODUCTION Malaria parasites cause human disease by invading and replicating inside red blood cells. In the case of Plasmodium falciparum , this can lead to severe forms of malaria that are a major cause of childhood mortality in Africa. This species of parasite enters the red blood cell through interactions with surface proteins including the glycophorins GYPA and GYPB, which determine the polymorphic MNS blood group system. In a recent genome-wide association study, we identified alleles associated with protection against severe malaria near the cluster of genes encoding these invasion receptors. RATIONALE Investigation of genetic variants at this locus and their relation to severe malaria is challenging because of the high sequence similarity between the neighboring glycophorin genes and the relative lack of available sequence data capturing the genetic diversity of sub-Saharan Africa. To better assess whether variation in the glycophorin genes could explain the signal of association, we generated additional sequence data from sub-Saharan African populations and developed an analytical approach to characterize structural variation at this complex locus. RESULTS Using 765 newly sequenced human genomes from 10 African ethnic groups along with data from the 1000 Genomes Project, we generated a reference panel of haplotypes across the glycophorin region. In addition to single-nucleotide polymorphisms and short indels, we assayed large copy number variants (CNVs) using sequencing read depth and uncovered extensive structural diversity. By imputing from this reference panel into 4579 severe malaria cases and 5310 controls from three African populations, we found that a complex CNV, here called DUP4, is associated with resistance to severe malaria and fully explains the previously reported signal of association. In our sample, DUP4 is present only in east Africa, and this localization, as well as the extent of similarity between DUP4 haplotypes, suggests that it has recently increased in frequency, presumably under natural selection due to malaria. To evaluate the potential functional consequences of this structural variant, we analyzed high-coverage sequence-read data from multiple individuals to generate a model of the DUP4 chromosome structure. The DUP4 haplotype contains five glycophorin genes, including two hybrid genes that juxtapose the extracellular domain of GYPB with the transmembrane and intracellular domains of GYPA. Noting that these predicted hybrids are characteristic of the Dantu antigen in the MNS blood group system, we sequenced a Dantu positive individual and confirmed that DUP4 is the molecular basis of the Dantu NE blood group variant. CONCLUSION Although a role for GYPA and GYPB in parasite invasion is well known, a direct link between glycophorin polymorphisms and clinical susceptibility to malaria has been elusive. Here we have provided a systematic catalog of CNVs, describing structural diversity that may have functional importance at this locus. Our results identify a specific variant that encodes hybrid glycophorin proteins and is associated with protection against severe malaria. This discovery calls for further work to determine how this particular molecular rearrangement affects parasite invasion and the red blood cell response and may lead us toward new parasite vulnerabilities that can be utilized in future interventions against this deadly disease.

Background: Plasmodium falciparum malaria is one of the most widespread and deadliest infectious diseases in children under five years in endemic areas. The disease has been a strong force for evolutionary selection in the human genome, and uncovering the critical host genetic factors that confer resistance to the disease would provide clues to the molecular basis of protective immunity and improve vaccine development initiatives. Methods: The effect of single nucleotide polymorphisms (SNPs) and plasma transforming growth factor beta (TGF-β) and interleukin 10 (IL-10) levels on malaria pathology was investigated in a case–control study of 1862 individuals from two major ethnic groups in three regions with intense perennial P. falciparum transmission in Cameroon. Thirty-four malaria candidate polymorphisms, including the sickle cell trait (HbS), were assayed on the Sequenom iPLEX platform while plasma TGF-β and IL-10 levels were measured by sandwich ELISA. Results: The study confirms the known protective effect of HbS against severe malaria and also reveals a protective effect of SNPs in the nitrogen oxide synthase 2 (NOS2) gene against malaria infection, anaemia and uncomplicated malaria. Furthermore, ADCY9 rs10775349 (additive G) and ABO rs8176746 AC individuals were associated with protection from hyperpyrexia and hyperparasitaemia, respectively. Meanwhile, individuals with the EMR1 rs373533 GT, EMR1 rs461645 CT and RTN3 rs542998 (additive C) genotypes were more susceptible to hyperpyrexia while both females and males with the rs1050828 and rs1050829 SNPs of G6PD, respectively, were more vulnerable to anaemia. Plasma TGF-β levels were strongly correlated with heterozygosity for the ADCY9 rs2230739 and HBB rs334 SNPs while individuals with the ABO rs8176746 AC genotype had lower IL-10 levels. Conclusion: Taken together, this study suggests that some rare polymorphisms in candidate genes may have important implications for the susceptibility of Cameroonians to severe malaria. Moreover using the uncomplicated malaria phenotype may permit the identification of novel pathways in the early development of the disease.

SummaryDespite the huge international endeavor to understand the genomic basis of malaria biology, there remains a lack of information about two human-infective species:Plasmodium malariaeandP. ovale. The former is prevalent across all malaria endemic regions and able to recrudesce decades after the initial infection. The latter is a dormant stage hypnozoite-forming species, similar toP. vivax. Here we present the newly assembled reference genomes of both species, thereby completing the set of all human-infectivePlasmodiumspecies. We show that theP. malariaegenome is markedly different to otherPlasmodiumgenomes and relate this to its unique biology. Using additional draft genome assemblies, we confirm thatP. ovaleconsists of two cryptic species that may have diverged millions of years ago. These genome sequences provide a useful resource to study the genetic basis of human-infectivity inPlasmodiumspecies.

Background Malaria and helminthiases frequently co-infect the same individuals in endemic zones. Plasmodium falciparum and helminth infections have long been recognized as major contributors to anaemia in endemic countries. Several studies have explored the influence of helminth infections on the course of malaria in humans but how these parasites interact within co-infected individuals remains controversial. Methods In a community-based longitudinal study from March 2011 to February 2012, the clinical and malaria parasitaemia status of a cohort of 357 children aged 6 months to 10 years living in Mutengene, south-western region of Cameroon, was monitored. Following the determination of baseline malaria/helminths status and haemoglobin levels, the incidence of malaria and anaemia status was determined in a 12 months longitudinal study by both active and passive case detection. Results Among all the children who completed the study, 32.5 % (116/357) of them had at least one malaria episode. The mean (±SEM) number of malaria attacks per year was 1.44 ± 0.062 (range: 1–4 episodes) with the highest incidence of episodes occuring during the rainy season months of March–October. Children

Background: The development and spread of antimalarial drug resistant parasites contributes to the global impact of the disease. In vivo efficacy assessments of treatments for Plasmodium falciparum malaria are essential for ensuring effective case management. Artemisinin-based combinations have been adopted as the first-line treatment for uncomplicated P. falciparum malaria in Cameroon since 2004. Methods: A total of 177 children aged six-months to 10 years with uncomplicated mono-infected falciparum malaria were randomized (1:1) to receive artesunate/sulphadoxine-pyrimethamine (AS/SP) or artesunate/amodiaquine (AS/AQ) pediatric tablets and followed up for 28 days according to the standard World Health Organization in vivo drug efficacy monitoring protocol. The primary and secondary endpoints were PCR uncorrected and corrected cure rates, as measured by adequate clinical and parasitological response (ACPR) on day 28. Results: The PCR corrected cure rate was high, overall (88.1%, 95% CI 83.1–93.1), 85.9% (95% CI 78.2–93.6), and 90.2% (95% CI 83.8–96.6) for AS/SP and AS/AQ, respectively. Twenty-one treatment failures were observed during follow-up, constituting one (4.6%), 14 (8.2%), and six (3.5%) early treatment failure (ETF), late clinical failure (LCF), and late parasitological failure (LPF), respectively. The drugs were well tolerated with no serious adverse events. Conclusions: Both AS/SP and AS/AQ are highly effective and well-tolerated treatments for uncomplicated P. falciparum malaria around the slope of Mount Cameroon.

Background Pregnant women in malaria endemic areas are at high risk of P. falciparum infection and its complications. This study investigated the prevalence and risk factors for P. falciparum infection and malaria among pregnant women reporting for first antenatal care (ANC) clinic visit in the mount Cameroon area. Methods Venous blood samples from consented pregnant women were screened for malaria parasitaemia by light microscopy. Haemoglobin levels, white blood cell (WBC) counts, lymphocyte counts and percentage were determined using an automated haematology analyser. Socio-demographic/economic data, environmental factors and use of malaria control measures were documented. Univariate and multivariate statistical analyses were used. Results Sixty-eight (22.4 %; N = 303) of the women enrolled were positive for P. falciparum parasitaemia. Malaria parasitaemia was significantly (P

Background Malaria remains a major global health burden despite the intensification of control efforts, due partly to the lack of an effective vaccine. Information on genetic diversity in natural parasite populations constitutes a major impediment to vaccine development efforts and is limited in some endemic settings. The present study characterized diversity by investigating msp1 block 2 polymorphisms and the relationship between the allele families with ethnodemographic indices and clinical phenotype. Method Individuals with asymptomatic parasitaemia (AP) or uncomplicated malaria (UM) were enrolled from rural, semi-rural and semi-urban localities at varying altitudes along the slope of mount Cameroon. P. falciparum malaria parasitaemic blood screened by light microscopy was depleted of leucocytes using CF11 cellulose columns and the parasite DNA genotyped by nested PCR. Results Length polymorphism was assessed in 151 field isolates revealing 64 (5) and 274 (22) distinct recombinant and major msp1 allelic fragments (genotypes) respectively. All family specific allelic types (K1, MAD20 and RO33) as well as MR were observed in the different locations, with K1 being most abundant. Eighty seven (60 %) of individuals harbored more than one parasite clone, with a significant proportion (p = 0.009) in rural compared to other settings. AP individuals had higher (p = 0.007) K1 allele frequencies but lower (p = 0.003) mean multiplicity of genotypes per infection (2.00 ± 0.98 vs. 2.56 ± 1.17) compared to UM patients. Conclusions These results indicate enormous diversity of P. falciparum in the area and suggests that allele specificity and complexity may be relevant for the progression to symptomatic disease.

Background. Falciparum malaria is an important pediatric infectious disease that frequently affects pregnant women and alters infant morbidity. However, the impact of some prenatal and perinatal risk factors such as season and intermittent preventive treatment during pregnancy (IPTp) on neonatal susceptibility has not been fully elucidated. Methods. A cohort of 415 infants born to women who were positive and negative for malaria was monitored in a longitudinal study in Southwestern Cameroon. The clinical and malaria statuses were assessed throughout, whereas paired maternal-cord and 1-year-old antimalarial antibodies were assayed by enzyme-linked immunosorbent assay. Infant susceptibility to malaria was ascertained after accounting for IPTp and season in the statistical analysis. Results. Malaria prevalence was higher in women (P = .039) who delivered during the rainy season and their infants (P = .030) compared with their dry season counterparts. Infants born to women who were positive for malaria (6.40 ± 2.83 months) were older (P = .028) than their counterparts who were negative for malaria (5.52 ± 2.85 months) when they experienced their first malaria episode. Infants born in September–November (adjusted odds ratio [OR] = 0.31, 95% confidence interval [CI] = 0.13–0.72) and to mothers on 1 or no IPTp-sulfadoxine/pyrimethamine (SP) dose (adjusted OR = 0.51, 95% CI = 0.28–0.91) were protected, whereas those born in the rainy season (adjusted OR = 2.82, 95% CI = 1.21–6.55) were susceptible to malaria. Conclusions. Intermittent preventive treatment during pregnancy and month of birth have important implications for infant susceptibility to malaria, with 2 or more IPTp-SP dosage possibly reducing immunoglobulin M production.

Background Malaria in pregnancy (MiP) has debilitating effects for both mother and neonate, with intermittent preventive treatment in pregnancy (IPTp) central to successful malaria control and management in this vulnerable group. However, the effectiveness of IPTp with sulphadoxinepy-rimethamine (SP) is threatened by the emergence of drug resistant Plasmodium falciparum parasites vastly documented in some settings but not in south-western Cameroon. This study sought to ascertain the level of resistance of natural parasite populations to SP in this area. Methods A total of 358 parturients were enrolled through a cross-sectional survey from May to October 2015. Malaria parasitaemia was determined by light microscopy using Giemsa-stained thick and thin smears of the peripheral blood, while DNA was extracted from dried blood spots of P. falciparum-positive samples by the Chelex-PBS method. SNPs in pfdhps and pfdhfr were then genotyped by nested polymerase chain reaction followed by allele-specific restriction analysis (ASRA). Results A total of 47 women (13.1%) had MiP, with a geometric mean parasitaemia density of 1064 parasites/µl of blood. The weight (p=0.038), gestational age (p=0.001), IPTp-SP usage (p Conclusions These results show the value of IPTp-SP usage and dosage in malaria parasitaemia control, in spite of the high prevalence of P. falciparum resistance to SP in the area, with implications for the control of malaria in this vulnerable group.

Mutations in the Plasmodium falciparum K13-propeller domain have recently been shown to be important determinants of artemisinin resistance in Southeast Asia. This study investigated the prevalence of K13-propeller polymorphisms across sub-Saharan Africa. A total of 1212 P. falciparum samples collected from 12 countries were sequenced. None of the K13-propeller mutations previously reported in Southeast Asia were found, but 22 unique mutations were detected, of which 7 were nonsynonymous. Allele frequencies ranged between 1% and 3%. Three mutations were observed in >1 country, and the A578S was present in parasites from 5 countries. This study provides the baseline prevalence of K13-propeller mutations in sub-Saharan Africa.

Insecticide Treated Nets (ITNs) have been shown to reduce morbidity and mortality, but coverage and proper utilization continues to be moderate in many parts of sub-Saharan Africa. The gains made through a nationwide free distribution were explored as well as the effect on malaria prevalence in semi-urban and rural communities in south western Cameroon. A cross sectional survey was conducted between August and December 2013. Information on net possession, status and use were collected using a structured questionnaire while malaria parasitaemia was determined on Giemsa-stained blood smears by light microscopy. ITN ownership increased from 41.9% to 68.1% following the free distribution campaign, with 58.3% (466/799) reportedly sleeping under the net. ITN ownership was lower in rural settings (adjusted OR = 1.93, 95%CI = 1.36–2.74, p

P. falciparum malaria is one of the most widespread and deadliest infectious diseases in children under five years in endemic areas. The disease has been a strong force for evolutionary selection in the human genome, and uncovering the critical human genetic factors that confer resistance to the disease would provide clues to the molecular basis of protective immunity that would be invaluable for vaccine development. We investigated the effect of single nucleotide polymorphisms (SNPs) on malaria pathology in a case- control study of 1862 individuals from two major ethnic groups in three regions with intense perennial P. falciparum transmission in Cameroon. Twenty nine polymorphisms in cytokine and toll-like receptor (TLR) genes as well as the sickle cell trait (HbS) were assayed on the Sequenom iPLEX platform. Our results confirm the known protective effect of HbS against severe malaria and also reveal a protective effect of SNPs in interleukin-10 (IL10) cerebral malaria and hyperpyrexia. Furthermore, IL17RE rs708567 GA and hHbS rs334 AT individuals were associated with protection from uncomplicated malaria and anaemia respectively in this study. Meanwhile, individuals with the hHbS rs334 TT, IL10 rs3024500 AA, and IL17RD rs6780995 GA genotypes were more susceptible to severe malarial anaemia, cerebral malaria, and hyperpyrexia respectively. Taken together, our results suggest that polymorphisms in some immune response genes may have important implications for the susceptibility to severe malaria in Cameroonians. Moreover using uncomplicated malaria may allow us to identify novel pathways in the early development of the disease.

Background To identify the factors that account for differences in clinical outcomes of malaria as well as its relationship with ethnicity, transmission intensity and parasite density. Methods A prospective study was conducted in nine health facilities in the Centre, Littoral and South West regions of Cameroon, and in three ethnic groups; the Bantu, Semi-Bantu and Foulbe. Children aged one month to 13 years, with diagnosis suggestive of malaria, were recruited and characterized using the WHO definition for severe and uncomplicated malaria. Malaria parasitaemia was determined by light microscopy, haematological analysis using an automated haematology analyser and glucose level by colorimetric technique. Results Of the febrile children screened, 971 of the febrile children screened fulfilled the inclusion criteria for specific malaria clinical phenotypes. Forty-nine (9.2%) children had cerebral malaria, a feature that was similar across age groups, ethnicity and gender but lower (P P P = 0.009) and Foulbe (P = 0.026) counterparts in the Centre region. The overall study case fatality was 4.8 (47/755), with cerebral malaria being the only significant risk factor associated with death. Severe anaemia, though a common and major clinical presentation, was not significantly associated with risk of death. Conclusion About half of the acutely febrile children presented with severe malaria, the majority being cases of severe malaria anaemia, followed by respiratory distress and cerebral malaria. The latter two were less prevalent in the Centre region compared to the other regions. Cerebral malaria and hyperpyrexia were the only significant risk factors associated with death.

The African continent continues to bear the greatest burden of malaria and the greatest diversity of parasites, mosquito vectors, and human victims. The evolutionary plasticity of malaria parasites and their vectors is a major obstacle to eliminating the disease. Of current concern is the recently reported emergence of resistance to the front-line drug, artemisinin, in South-East Asia in Plasmodium falciparum , which calls for preemptive surveillance of the African parasite population for genetic markers of emerging drug resistance. Here we describe the Plasmodium Diversity Network Africa (PDNA), which has been established across 11 countries in sub-Saharan Africa to ensure that African scientists are enabled to work together and to play a key role in the global effort for tracking and responding to this public health threat.

In the many areas where human malaria and helminthiases are co-endemic, schoolchildren often harbour the heaviest infections and suffer much of the associated morbidity, especially when co-infected. In one such area, the Buea district, in south-western Cameroon, two cross-sectional surveys, together covering 263 apparently healthy schoolchildren aged 4-12 years, were recently conducted. The prevalences of fever, malarial parasitaemia and intestinal helminth infections, the seroprevalences of anti-Plasmodium falciparum IgG and IgE and anti-glycosylphosphatidylinositol (anti-GPI) IgG, plasma concentrations of total IgE, and the incidence of anaemia were all investigated. The mean (S.D.) age of the study children was 7.56 (1.82) years. Overall, 156 (59.3%) of the children were found parasitaemic, with a geometric mean parasitaemia of 565 parasites/microl. Parasitaemia and fever were significantly associated (P=0.042). The children who lived at low altitude, attending schools that lay 400-650 m above sea level, had significantly higher parasitaemias than their high-altitude counterparts (P

Objectives To investigate the effects of age, gravidity, and gestational age on peripheral malaria parasitemia and functional T helper (Th) cell heterogeneity in pregnant women. Methods Maternal age, gravidity, and gestational age were recorded and peripheral venous blood collected from 175 women attending antenatal clinics in south western Cameroon between March and September 2002. The blood was checked for malaria parasitemia by light microscopy and plasma levels of interleukin (IL)-4 and human interferon (IFN)-γ were measured by indirect enzyme-linked immunosorbent assay. Results Malaria parasites were detected in 45 (25.4%) of 174 women, with rates similar for different age groups, trimesters of pregnancy, and gravidity. The geometric mean parasite density was 565, and parasite density was significantly higher in younger than in older women. For all groups combined, the mean IL-4 level was significantly higher than the mean IFN-γ ( P = 0.0004), irrespective of the presence and density of malaria parasites, gravidity except for women in their first trimester of pregnancy and grandmultiparas, who had similar levels of IFN-γ and IL-4. In general, the cytokine profile was biased toward Th2-type of responses in 112 (84.3%) of 132 women. Conclusions In this study the ability to control malaria parasitemia during pregnancy was found to be predominantly age dependent, suggesting naturally acquired immunity. Furthermore, the systemic cytokine profile was found to be biased towards Th2 responses, a prerequisite for a successful pregnancy. This pattern was unaffected by maternal age, gestational age, gravidity, or parasitemia.

Background Malaria in pregnancy is common in sub-Saharan Africa where it contributes to perinatal morbidity and mortality. Use of insecticide-treated bed nets and intermittent preventive therapy with sulfadoxine–pyrimethamine during pregnancy are effective but underutilized interventions to prevent infection. Factors associated with bed net ownership and usage, and use of prophylaxis among recently pregnant women in Cameroon were investigated. Methods National data from the 2011 Cameroon Demographic Health Survey was used to identify women with a pregnancy within the previous 5 years. Logistic regression models were created to assess for independent predictors of reported bed net ownership, bed net usage, and the use of malaria prophylaxis medications during pregnancy. Results Nearly one in two women surveyed had a recent pregnancy (n = 7647). In this group, bed net ownership and usage rates were low (33.7 and 16.9%, respectively); 61.6% used medication for malaria prophylaxis during pregnancy. Bed net ownership and usage were associated with maternal literacy (aOR 1.4 for net usage, 95% CI 1.1–1.8) and the presence of children under age 5 in the home (aOR 2.3 for net usage, 95% CI 1.6–3.3). The use of malaria prophylaxis medication was associated with measures of healthcare access (aOR 17.8, 95% CI 13–24.5 for ≥4 antenatal care visits), higher maternal education (aOR 1.5, 95% CI 1.1–2.1) and maternal literacy (aOR 1.4, 95% CI 1.1–1.7). Conclusions Women in Cameroon and their antenatal providers missed many opportunities to prevent malaria in pregnancy. Efforts toward ensuring universal bed net provision, consistent antenatal care and the education of girls are likely to improve birth outcomes attributable to malaria infection.

Background The determinants and barriers for delivery and uptake of IPTp vary with different regions in sub-Saharan Africa. This study evaluated the determinants of ANC clinic attendance and IPTp-SP uptake among parturient women from Mount Cameroon Area and hypothesized that time of first ANC clinic attendance could influence uptake of IPTp-SP/dosage and consequently malaria parasite infection status at delivery. Methods Two cross sectional surveys were carried out at the Government Medical Centre in the Mutengene Health Area, Mt Cameroon Area from March to October 2007 and June 2008 to April 2009. Consented parturient women were consecutively enrolled in both surveys. In 2007, socio-demographic data, ANC clinic attendance, gestational age, fever history and reported use/dosage of IPTp-SP were documented using a structured questionnaire. In the second survey only IPT-SP usage/dosage was recorded. Malaria parasitaemia at delivery was determined by blood smear microscopy and placental histology. Results and discussion In 2007, among the 287 women interviewed, 2.2%, 59.7%, and 38.1% enrolled in the first, second and third trimester respectively. About 90% of women received at least one dose SP but only 53% received the two doses in 2007 and by 2009 IPTp-two doses coverage increased to 64%. Early clinic attendance was associated (P = 0.016) with fever history while being unmarried (OR = 2.2; 95% CI: 1.3-3.8) was significantly associated with fewer clinic visits (