Malaria-infected Individuals Research Articles

Polymorphisms in the Pfcrt, Pfmdr1, and Pfk13 genes of Plasmodium falciparum isolates from southern Brazzaville, Republic of Congo.

This study aimed to analyze polymorphisms in Pfcrt, Pfmdr1, and Pfk13 genes' markers of resistance to Artemisinin-based combination therapy (ACT), in Plasmodium falciparum isolates from southern Brazzaville, 15 years after the adoption of ACT in the Republic of Congo. A total of 369 microscopy-confirmed malaria-infected individuals were enrolled from March to October 2021 in the community and in health facilities during a cross-sectional study. The K76T mutation in the Pfcrt gene, N86Y and Y184F mutations in the Pfmdr1 gene were investigated using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) while the codons region (1005-1300) of the Pfmdr1gene, and Pfk13 gene were sequenced. The prevalences of K76T, N86Y, Y184F mutations were 26.0%, 6.8%, and 27.7%, respectively. However, no mutations were detected in codons 1034, 1042, and 1246 of the Pfmdr1 gene. None of the mutations previously associated with artemisinin-based resistance were detected in the Pfk13 gene. The results reveal a significant decrease in the prevalence of K76T, N86Y, Y184F mutations, in Plasmodium falciparum isolates following the change of therapeutic policy. As artemisinin resistance is emerging throughout Africa, continued surveillance for early detection of these mutations and relevant partner markers of drug resistance are recommended in the Republic of Congo.

Plasmodium falciparum genetic diversity and multiplicity of infection among asymptomatic and symptomatic malaria-infected individuals in Uganda.

Plasmodium falciparum (P. falciparum) remains a significant public health challenge globally, especially in sub-Saharan Africa (SSA), where it accounts for 99% of all malaria infections. The outcomes of P. falciparum infection vary, ranging from asymptomatic to severe, and are associated with factors such as host immunity, parasite genetic diversity, and multiplicity of infection (MOI). Using seven neutral microsatellite markers, the current study investigated P. falciparum genetic diversity and MOI in both asymptomatic and symptomatic malaria individuals in Uganda. This cross-sectional study analyzed 225 P. falciparum isolates from both asymptomatic and symptomatic malaria patients, ranging in age from 6months to ≥ 18years. P. falciparum genetic diversity, MOI, and multi-locus linkage disequilibrium (LD) were assessed through genotyping of seven neutral microsatellite markers: Poly-α, TA1, TA109, PfPK2, 2490, C2M34-313, and C3M69-383. Genetic data analysis was performed using appropriate genetic analysis software. P. falciparum infections exhibited high genetic diversity in both asymptomatic and symptomatic individuals. The mean expected heterozygosity (He) ranged from 0.79 in symptomatic uncomplicated malaria cases to 0.81 in asymptomatic individuals. There was no significant difference (p = 0.33) in MOI between individuals with asymptomatic and symptomatic infections, with the mean MOI ranging from 1.92 in symptomatic complicated cases to 2.10 in asymptomatic individuals. Polyclonal infections were prevalent, varying from 58.5% in symptomatic complicated malaria to 63% in symptomatic uncomplicated malaria cases. A significant linkage disequilibrium (LD) was observed between asymptomatic and symptomatic uncomplicated/complicated infections (p < 0.01). Genetic differentiation was low, with FST values ranging from 0.0034 to 0.0105 among P. falciparum parasite populations in asymptomatic and symptomatic uncomplicated/complicated infections. There is a high level of P. falciparum genetic diversity and MOI among both symptomatic and asymptomatic individuals in Uganda. Asymptomatic carriers harbor a diverse range of parasites, which poses challenges for malaria control and necessitates targeted interventions to develop effective strategies.

Asymptomatic Plasmodium falciparum and HBV coinfections among inmates at Owo Correctional Facility, Nigeria

BackgroundMalaria and hepatitis B are significant public health infections in Nigeria. Coinfection with both pathogens is common where both diseases are endemic. Epidemiological surveys are essential for determining the burden of diseases and possible coinfection with multiple pathogens in vulnerable populations. There has been a lack of reports on HBV/malaria coinfection, particularly among marginalized groups in Ondo State. Thus, we used malaria microscopy and the HBsAg serological test to examine the prevalence of asymptomatic malaria parasitemia and HBV infections respectively among inmates at the Nigerian Correctional Center in Owo, Ondo State, Nigeria.ResultsOut of the 126 prisoners and staff members who were evaluated, 20.6% and 7.9% tested positive for malaria and HBV infections, respectively. It was discovered that 1.6% of the individuals were coinfected with malaria and HBV. Plasmodium falciparum was the only malaria species recovered in malaria-infected individuals. Except for HBV, where gender was found to differ considerably with the proportion of HBV infection, variations in single infections with either pathogen did not vary with demographic characteristics.ConclusionWe suggest that the prison system should be considered in healthcare programs to improve the health of inmates.

A systematic review and meta-analysis of cortisol levels in Plasmodium infections

Malaria has complex interactions with host physiology, including alterations in cortisol levels. Cortisol, a key hormone in the stress response, is known to be dysregulated in various infectious diseases. This systematic review and meta-analysis aimed to elucidate the relationship between Plasmodium infection and cortisol levels, shedding light on the intricate interplay between the parasite and the host’s endocrine system. The methodological protocol for assessing cortisol levels in malaria patients was registered in PROSPERO (CRD42024496578), a widely recognized international prospective register of systematic reviews. This registration ensures transparency and minimizes the risk of bias in our research. A comprehensive search strategy was employed across major databases, including Embase, PubMed, Scopus, and Medline, to include studies that reported cortisol levels in infected patients. The qualitative synthesis was undertaken to synthesize the difference in cortisol levels between malaria-infected and uninfected individuals. The meta-analysis employed the random effects model in the quantitative synthesis to calculate the effect estimate. The review included a total of 20 studies, with a substantial number conducted in Africa, followed by Asia and South America. Most included studies (13/20, 65%) reported higher cortisol levels in infected patients than in uninfected patients. The meta-analysis confirmed significantly higher cortisol levels in infected patients compared to uninfected individuals (P < 0.0001, standardized mean difference (SMD): 1.354, 95% confidence interval: 0.913 to 1.795, I2: 88.3%, across 15 studies). Notably, the method for cortisol measurement and the type of blood sample used (serum or plasma) were significant moderators in the analysis, indicating that these factors may influence the observed relationship between Plasmodium infection and cortisol levels. The systematic review and meta-analysis confirmed that Plasmodium infection is associated with increased cortisol levels, highlighting the intricate relationship between the disease and the host stress response. These findings underscore the potential of cortisol as a supplementary biomarker for understanding the pathophysiological impact of malaria. By providing insights into the stress-related mechanisms of malaria, this comprehensive understanding can inform future research and potentially enhance disease management and treatment strategies, particularly in regions heavily burdened by malaria.

Possible alteration in serum ferritin level in malaria infected HIV seropositive individuals in Nauth, Nnewi, Nigeria

The role of Ferritin in monitoring disease progression in immune compromised HIV individuals with an underlying active infection like malaria is a subject of growing research. Ferritin being an acute phase protein, plays important role in assessing the range of damage due to inflammation in immunosuppressed patients leaving in highly endemic malaria regions. The levels of serum ferritin in malaria infected HIV positive individuals in Nnamdi Azikiwe University teaching hospital (NAUTH), Nnewi, Anambra State, Nigeria, was assessed. Questionnaire was used to obtain the demographic details of the participants, and to rule out other inflammatory infections. 88 participants of the age group 18 - 65 years, comprising 24 with HIV infection, 22 with HIV and Malaria co-infection, 22 with Malaria infection, and a control group of 22 individuals with neither HIV nor malaria infection were randomly recruited. Ferritin level was determined using enzyme linked immunosorbent assay technique and a cross sectional prospective study design was used. A significantly high mean serum ferritin level was observed in HIV infected individuals with and/ or without malaria co-infection than in malaria positive and control group (p&lt;0.05 respectively). Serum ferritin level was significantly higher in female participants than in male counterparts (p &lt; 0.05). Serum ferritin level was significantly higher in individuals with CD4 count &gt;500 than in CD4 count ≤ 500 (p &lt; 0.05). Blood pressure was significantly higher in HIV infected and malaria positive individuals when compared with controls. The increased serum ferritin level and higher blood pressure in HIV infected participants suggests active inflammatory process, reduced immunity and hypertension which may have worsened by malaria co-infection. This may subsequently lead to vascular and endothelia damage causing disease severity.

Spatiotemporal analysis of within-country imported malaria in Brazilian municipalities, 2004-2022.

Human mobility has challenged malaria elimination efforts and remains difficult to routinely track. In Brazil, administrative records from the Ministry of Health allow monitoring of mobility locally and internationally. Although most imported malaria cases are between municipalities in Brazil, detailed knowledge of patterns of mobility is limited. Here, we address this gap by quantifying and describing patterns of malaria-infected individuals across the Amazon. We used network analysis, spatial clustering, and linear models to quantify and characterize the movement of malaria cases in Brazil between 2004 and 2022. We identified sources and sinks of malaria within and between states. We found that between-state movement of cases has become proportionally more important than within-state, that source clusters persisted longer than sink clusters, that movement of cases into sinks was seasonal while movement out of sources was not, and that importation is an impediment for subnational elimination in many municipalities. We elucidate the vast travel networks of malaria infected individuals that characterize the Amazon region. Uncovering patterns of malaria case mobility is vital for effective microstratification within Brazil. Our results have implications for intervention stratification across Brazil in line with the country's goal of malaria elimination by 2035.

Characterization of urinary metabolites associated with malaria infection using infra-red spectroscopy and liquid chromatography–mass spectrometry in South Western Uganda

Early malaria diagnosis improves outcomes during malaria treatment; routine diagnostic techniques rely on blood samples obtained invasively. Therefore, this study used infra-red (IR) spectroscopy coupled with Principle Component Analysis (PCA) to study the urinary profile of malaria patients and that of controls aimed at understanding metabolite perturbation during malaria infection so as to contribute towards development of non-invasive malaria diagnosis methods. Freeze dried human urine samples form malaria infected individuals (cases) and controls were screened in the IR region of 4000 cm−1 to 600 cm−1 and overall spectral differences were observed at wave numbers 1618 cm−1, 1679 cm−1 (amino acids). Peaks at 3030 cm−1 (NH4+) and 940 cm−1 (O–H of carboxylic acids) showed high absorbance in patients compared to controls. Liquid-chromatography–mass spectrometry (LC–MS/MS) was used to quantify amino acids in the urine samples and the results indicated a significant increase of amino acid cystine (P = 0.012). Lysine and tyrosine also increased in patients compared to controls. The use of IR-PCA differentiated clusters of urine samples from patients with malaria from control and the demonstrated amino acid perturbation is consistent with malaria infection. This data provides baseline information for application in development of a non-invasive diagnostic tests for malaria.

Shotgun Characterization of the Circulating IgM Antigenome of an Infectious Pathogen by Immunocapture-LC-MS/MS from Dried Serum Spots.

One of the main challenges in compiling the complete collection of protein antigens from pathogens for the selection of vaccine candidates or intervention targets is to acquire a broad enough representation of them to be recognized by the highly diversified immunoglobulin repertoire in human populations. Dried serum spot sampling (DSS) retains a large repertoire of circulating immunoglobulins from each individual that can be representative of a population, according to the sample size. In this work, shotgun proteomics of an infectious pathogen based on DSS sampling coupled with IgM immunoprecipitation, liquid chromatography-mass spectrometry (LC-MS/MS), and bioinformatic analyses was combined to characterize the circulating IgM antigenome. Serum samples from a malaria endemic region at different clinical statuses were studied to optimize IgM binding efficiency and antibody leaching by varying serum/immunomagnetic bead ratios and elution conditions. The method was validated using Plasmodium falciparum extracts identifying 110 of its IgM-reactive antigens while minimizing the presence of human proteins and antibodies. Furthermore, the IgM antigen recognition profile differentiated between malaria-infected and noninfected individuals at the time of sampling. We conclude that a shotgun proteomics approach offers advantages in providing a high-throughput, reliable, and clean way to identify IgM-recognized antigens from trace amounts of serum. The mass spectrometry raw data and metadata have been deposited with ProteomeXchange via MassIVE with the PXD identifier PXD043800.

Status in Malaria Vaccine Development: Basic aspects of Vaccine, Mechanism of actions, Vaccine pipelines, Stage oriented immune response ‘Challenges and Opportunities’

Malaria is considered as a systemic syndrome caused by infection of the red blood cells by intracellular protozoan parasites of the genus Plasmodium and is transmitted by the bite of infected and physiologically excited female anopheline mosquito, which feeds on mamamalian blood to produce and mature its eggs. Vaccination is believed to be one of the most effective approaches to tackle morbidity and mortality related malaria and its approach targets the malaria life stage factors like the pre-erythrocyticproteins (RTSs, ChAd63/MVA, METRAP, PSPZ, PfceITos…), the blood stage proteins (EBA175, AMA1, GMZ1, P27A, MSP3, MSP1, RH5, sexual stage proteins (Pfs25, Pfs48, Pfs230 and Multi-stage /multi-epitope/antigen combination vaccines ((PfCP-2. 9 chimeric (AMA1 and MSP1–19)). Even if the vaccine trials against malaria was began early in 1930s, currently the one most advanced pre-erythrocyticvaccine, RTS, S vaccine has been launched with good safety profile (efficacy of 30-50%). New approaches like combining different types of adjuvants into antigen‐specific formulations improved efficacy of a particular vaccine and its formulations offer a wide spectrum of opportunities in malaria vaccine research. Frequent and multiple infections gradually lead to the development of anti-parasite immunity which results in very low or undetectable parasitemia in malaria-infected individuals. Sterilizing immunity against malarial parasite, though never fully achieved, results in a high degree of immune response, low levels of parasitemia, and an asymptomatic carrier status For unsuccessful trials of malaria vaccine, there are so many challenges that are associated to logistic (high cost-effective public health intervention to control and regulate pathway complicity ), immunologic (polymorphism of the malaria parasite antigens in each life stage, the immune evasion strategy of the parasite… ), and technical challenges related to miss identification of malaria vaccine candidates, selection adjuvants and route of administration. Although there were tackles to malarial vaccine trials, it was reported that there are fine opportunities to proceed on the track.

First Serological Evidence of West Nile Virus among Individuals with Febrile Illness in a Tertiary Hospital in Port Harcourt, Nigeria

Aims: West Nile Virus (WNV) infection can cause severe illness. Very little is known about the seroepidemiology of WNV infection in individuals with febrile illness in Nigeria and many other developing countries. This study was carried out to determine the seroprevalence of WNV in individuals with febrile illness attending a tertiary hospital in Port Harcourt, Nigeria and to determine if there was an association between WNV infection with age and sex.&#x0D; Study Design: Cross-Sectional Study&#x0D; Place and Duration of Study: Port Harcourt in Rivers State, Nigeria from September 2019 to December 2019.&#x0D; Methods: Human sera were obtained and WNV IgG was determined using the Enzyme-Linked Immunosorbent Assay (ELISA) technique.&#x0D; Results: Of the 90 study subjects tested, WNV IgG antibodies were present in 27 (30.0%) study participants while 63 (70.0%) study participants were seronegative for WNV IgG antibody. With age, a higher prevalence of WNV occurred among 61-70-year-olds (31.3%, n= 5) compared to 41-60 (30.8%, n= 12) and 20-40 (28.6%, n= 10). A higher prevalence of WNV IgG antibodies occurred in males (34.3%, n=12) than their female counterparts (30.9%, n=17). This study indicated that there is no association between WNV infection with age and sex.&#x0D; Conclusion and Recommendations: These results show that WNV is circulating in Rivers State and has accounted for malaria-like infection in the region. It is recommended that WNV serological testing for malaria-infected individuals should be included as a routine test since they are most likely to present similar symptoms of WNV fever. Also, proper hygiene which includes eliminating mosquito breeding sites is recommended to mitigate the spread of West Nile Virus infection.

Detection of Plasmodium falciparum in Saliva and Stool Samples from Children Living in Franceville, a Highly Endemic Region of Gabon.

Due to the difficulty of obtaining blood samples, which is the invasive method that is currently used for the detection of Plasmodium spp., alternative diagnostic sampling methods that are effective and non-invasive are needed, particularly for long-term studies. Saliva and stool samples from malaria-infected individuals contain trace amounts of Plasmodium DNA and therefore could be used as alternatives. Malaria was screened using rapid diagnosis tests and confirmed via microscopy. Nested PCR tests targeting the Plasmodium falciparum-specific STEVOR gene were performed for blood, saliva and stool samples that were positive for malaria. Three hundred sixty-seven (367) children were enrolled and eighty (22.22%) were confirmed to be positive for malaria. Matched blood, saliva and stool samples were available for 35 children. By using blood smears as the gold standard for the diagnosis of malaria, our study indicates that Plasmodium DNA was more detectable in blood (100%) than in saliva (22.86%) and stools (14.29%). Applying qPCR to the STEVOR gene to detect Plasmodium falciparum DNA in saliva and stool samples cannot be considered as an alternative to the current malaria detection processes using blood specimens.

Differences in catalase levels between malaria-infected individuals and uninfected controls: a systematic review and meta-analysis

Inconsistent catalase (CAT) research necessitates a comprehensive review of CAT levels among patients with malaria to achieve better therapeutic strategies. This study aimed to systematically review and meta-analyze available literature on CAT levels in nonpregnant and pregnant individuals with malaria compared with those in uninfected controls, with the goal of providing a robust evidence base for future research and potential interventions. Following PRISMA guidelines, a systematic literature search across six databases was conducted to examine CAT levels in patients with malaria. Data was extracted independently by two reviewers, and study quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. The standardized mean difference of CAT levels was calculated with heterogeneity assessment. Subgroup and sensitivity analyses were conducted to explore heterogeneity and assess the robustness of the findings. Publication bias was visually and statistically assessed and corrected, if necessary. Statistical analyses were performed using Stata software, with a significance level set at P < 0.05. Nineteen studies were included in the review. These studies, published from before 2000 to 2023, primarily from Africa and Asia, focused on different Plasmodium species and age groups. Results of qualitative synthesis among nonpregnant individuals consistently showed lower CAT levels in malaria-infected individuals, although some studies reported higher levels. No significant differences in CAT levels were found between malaria-infected and uninfected individuals, as demonstrated by a meta-analysis overall (P = 0.05, Hedges’ g: − 0.78, 95% confidence interval (CI): (− 1.56)–0.01, I2: 98.47, 15 studies), but subgroup analyses showed significant differences in CAT levels in studies conducted in Africa (P = 0.02, Hedges’ g: − 0.57, 95% CI: − 1.02–(0.11), I2: 91.81, 7 studies), and in studies that specifically focused on children (P = 0.03, Hedges’ g: − 0.57, 95% CI: − 1.07–(− 0.07), I2: 87.52, 4 studies). Pregnant women showed variations in CAT levels across trimesters. This study provides valuable insights into the association between malaria infection and CAT enzyme levels, particularly in nonpregnant individuals. Furthermore, well-designed studies are essential to decoding the intricacies of this relationship, which could have significant implications for understanding disease processes and improving patient care.

Exosome-derived long noncoding RNAs: Mediators of host-Plasmodium parasite communication.

Overcoming challenges associated with malaria eradication proves to be a formidable task due to the complicated life cycle exhibited by the malaria parasite and the lack of safe and enduring vaccines against malaria. Investigating the interplay between Plasmodium parasites and their mammalian hosts is crucial for the development of novel vaccines. Long noncoding RNAs (lncRNAs) derived from Plasmodium parasites or host cells have emerged as potential signaling molecules involved in the trafficking of proteins, RNA (mRNAs, miRNAs, and ncRNAs), and DNA. These lncRNAs facilitate the interaction between hosts and parasites, impacting normal physiology or pathology in malaria-infected individuals. Moreover, they possess the capacity to regulate immune responses and associated signaling pathways, thus potentially influencing chromatin organization, epigenetic modifications, mRNA processing, splicing, and translation. However, the functional role of exosomal lncRNAs in malaria remains poorly understood. This review offers a comprehensive analysis of lncRNA and exosomal lncRNA profiles during malaria infection. It presents an overview of recent progress in elucidating the involvement of exosomal lncRNAs in host-parasite interactions. Additionally, potential exosomal lncRNAs linked to the domains of innate and adaptive immunity in the context of malaria are proposed. These findings may contribute to the discovery of new diagnostic and therapeutic strategies for malaria. Furthermore, the need for additional research was highlighted that aimed to elucidate the mechanisms underlying lncRNA transportation into host cells and their targeting of specific genes to regulate the host's immune response. This knowledge gap presents an opportunity for future investigations, offering innovative approaches to enhance malarial control. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease.

Dynamic effects of asymptomatic infections on malaria transmission

Asymptomatic transmission is a way of spreading malaria from asymptomatic infected individuals to susceptible ones by mosquito bites. Asymptomatic malaria-infected individuals do not show clinical symptoms, but they can still transmit the disease. Motivated by mathematical models with asymptomatic infections, we propose a human–mosquito model for malaria transmission dynamics with asymptomatic infections and standard incidence rates. We calculate the basic reproduction number R0 of the model and then prove that the model exists a unique endemic equilibrium E∗ if and only if R0>1. By the Lyapunov function method, the global stability of equilibria of the model is obtained. It is shown that the disease-free equilibrium E0 is globally asymptotically stable (GAS) if and only if R0≤1, which implies that malaria will be extinct; and the endemic equilibrium E∗ is GAS if and only if R0>1, which suggests that malaria will persist. In addition, the effects of partial malaria-related parameters on the dynamic transmission of malaria are studied and analysed numerically. The results of numerical simulations show that asymptomatic infections can shift the epidemic dynamics of malaria and have a significant influence on the transmission of malaria.

Serum Ferritin and Asymptomatic Malaria: A study in Calabar, Nigeria.

Introduction Ferritin is a blood cell protein that contains iron. The serum ferritin level is widely accepted as an accurate indicator of body iron store being the only factor that can give a semi-quantitative indication of the levels of Iron storage. Increased serum ferritin has been reported in asymptomatic malaria infection.This study was done to determine the serum ferritin levels in asymptomatic malaria individuals in Calabar, Cross River State, Nigeria. Ninety (90) apparently healthy subjects were recruited, both male and female within the age of 18 to 65 years. Materials and Method The serum ferritin level was assayed using ELISA quantitative method. The Hb and PCV were also assayed using the automated cellular counter Sysmex Kx-21N. Malaria parasite detection was through examination of peripheral blood smears using 2% Giemsa. Results The mean serum ferritin levels for the malaria infected subjects was (25.11±1.27ng/ml), and this was significantly higher than the uninfected subjects (16.81±4.66ng/ml) (P&lt;0.05). Mean serum ferritin level for infected males was (20.95±8.79ng/ml) which is slightly higher than uninfected males (16.01±3.53ng/ml) (P&gt;0.05). The results also show mean serum ferritin for infected females to be (30.57±3.42ng/ml) which is higher than the uninfected females (18.65±1.98ng/ml). This result likewise shows significantly low level of Hb(12.97±1.5g/dl) and PCV (0.38±2.18L/L) in apparently healthy malaria infected individuals while high level of Hb(15.20±1.73g/dl) and PCV (0.44±1.58L/L) were observed among the uninfected subjects. There was also significant difference seen in infected male and infected female subjects, likewise the aparasitaemic males and females had significant difference (P&lt;0.05). Conclusion This study has shown that asymptomatic malaria parasitaemia increases serum ferritin level, hence serum ferritin estimation without examination for malaria parasitaemia in malaria endemic area such as Calabar, Nigeria may not be reliable. The study also shows that asymptomatic malaria parasitaemia constitutes a significant disease burden and a challenge that should be of global health concern

Prevalence of Plasmodium falciparum gametocytaemia in asymptomatic school children before and after treatment with dihydroartemisinin-piperaquine (DP)

BackgroundAsymptomatic Plasmodium carriers form the majority of malaria-infected individuals in most endemic areas. A proportion of these asymptomatically infected individuals carry gametocytes, the transmissible stages of malaria parasites, that sustain human to mosquito transmission. Few studies examine gametocytaemia in asymptomatic school children who may form an important reservoir for transmission. We assessed the prevalence of gametocytaemia before antimalarial treatment and monitored clearance of gametocytes after treatment in asymptomatic malaria children. MethodsA total of 274 primary school children were screened for P. falciparum parasitaemia by microscopy. One hundred and fifty-five (155) parasite positive children were treated under direct observation with dihydroartemisinin-piperaquine (DP). Gametocyte carriage was determined by microscopy seven days prior to treatment, day 0 before treatment, and on days 7, 14 and 21 post initiation of treatment. ResultsThe prevalence of microscopically-detectable gametocytes at screening (day −7) and enrolment (day 0) were 9% (25/274) and 13.6% (21/155) respectively. Following DP treatment, gametocyte carriage dropped to 4% (6/135), 3% (5/135) and 6% (10/151) on days 7, 14 and 21 respectively. Asexual parasites persisted in a minority of treated children, resulting in microscopically detectable parasites on days 7 (9%, 12/135), 14 (4%, 5/135) and 21 (7%, 10/151). Gametocyte carriage was inversely correlated with the age of the participants (p = 0.05) and asexual parasite density (p = 0.08). In a variate analysis, persistent gametocytaemia 7 or more days after treatment was significantly associated with post-treatment asexual parasitaemia at day 7 (P = 0.027) and presence of gametocytes on the day of treatment (P < 0.001). ConclusionsThough DP provides both excellent cure rates for clinical malaria and a long prophylactic half-life, our findings suggest that after treatment of asymptomatic infections, both asexual parasites and gametocytes may persist in a minority of individuals during the first 3 weeks after treatment. This indicates DP may be unsuitable for use in mass drug administration strategies towards malaria elimination in Africa.

Morphological atypia and molecular profile of Plasmodium vivax: Findings from an outbreak in the Brazilian Amazon.

This study aimed to perform morphological and molecular analyses of parasites isolated from the blood of malaria-infected individuals during an outbreak in the Microregion of Cametá, State of Pará, Brazilian Amazon. A total of 260 positive samples were identified by microscopy as Plasmodium vivax; however, in three samples, forms considered unusual for the species were found and defined as morphological atypia of P. vivax. Single P. vivax infection was confirmed by qPCR in all samples. Among 256 genotyped samples, the VK247 genotype alone was identified in 255 samples, and the VK210 genotype was found in only one. The study showed that this malaria outbreak was caused by the etiological agent P. vivax, and for the first time, morphological atypia was described in isolates circulating in Brazil. Likewise, for the first time, the VK247 genotype was detected predominantly in single infections in an area of the State of Pará, which may suggest a greater circulation of the genotype in the region.

Multicohort transcriptome analysis of whole blood identifies robust human response signatures in Plasmodium falciparum infections

BackgroundTo understand how Plasmodium falciparum malaria is controlled, it is essential to elucidate the transcriptomic responses of the human host in naturally-exposed populations. Various individual studies of the human transcriptomic responses to naturally transmitted P. falciparum infections have been reported with varying results. Multicohort gene expression analysis by aggregating data from diverse populations into a single analysis will increase the reproducibility and reliability of the results.MethodsIn this study, discovery cohorts GSE1124-GPL96, GSE34404, GSE117613, and validation cohort GSE35858 were obtained from the Gene Expression Omnibus. A meta-analysis using data from the multicohort studies was performed to identify the differentially expressed genes (DEGs) between malaria-infected and noninfected individuals using the MetaIntegrator R package. Subsequently, the protein–protein interaction (PPI) networks of the DEGs were constructed using Cytoscape software. Significant modules were selected, and the hub genes were identified using the CytoHubba and MCODE plug-ins. Multicohort WGCNA was conducted to find a correlation between modules and malaria infection. Furthermore, the immune cell profile of the peripheral blood in different groups was identified using ssGSEA.ResultsThese analyses reveal that neutrophil activation, neutrophil-mediated immunity, and neutrophil degranulation are involved in the human response to natural malaria infection. However, neutrophil cell enrichment and activation were not significantly different between mild malaria and severe malaria groups. Malaria infection also downregulates host genes in ribosome synthesis and protein translation and upregulates host cell division-related genes. Furthermore, immune cell profiling analysis shows that activated dendritic cells and type 2 T helper cells are upregulated, while activated B cells, immature B cells, and monocytes are downregulated in the malaria-infected patients relative to the noninfected individuals. Significantly higher enrichment of activated dendritic cell-related genes and significantly lower enrichment of monocyte-related genes are also observed in the peripheral blood of the severe malaria group than in the mild malaria group.ConclusionThese results reveal important molecular signatures of host responses to malaria infections, providing some bases for developing malaria control strategies and protective vaccines.

Imported malaria definition and minimum data for surveillance

The mobility of malaria-infected individuals poses challenges to elimination campaigns by way of spreading parasite drug resistance, straining country-to-country collaboration, and making routine data collection difficult, especially in resource-poor settings. Nevertheless, no concerted effort has been made to develop a common framework to define the spatial and temporal components of an imported malaria case and recommend the minimum data needed to identify it. We conducted a scoping review of imported malaria literature from 2010 to 2020 which showed that definitions vary widely, and local capabilities of detecting importation are often restricted in low-income countries. Following this, we propose a common definition for imported malaria and the minimum data required to identify a case, depending on the country’s capability of conducting an epidemiological investigation. Lastly, we utilize the proposed definition using data from Brazil to demonstrate both the feasibility and the importance of tracking imported cases. The case of Brazil highlights the capabilities of regular surveillance systems to monitor importation, but also the need to regularly use these data for informing local responses. Supporting countries to use regularly collected data and adopt a common definition is paramount to tackling the importation of malaria cases and achieving elimination goals set forth by the World Health Organization.

Process development and preclinical evaluation of a major Plasmodium falciparum blood stage vaccine candidate, Cysteine-Rich Protective Antigen (CyRPA).

Plasmodium falciparum Cysteine-Rich Protective Antigen (CyRPA) is an essential, highly conserved merozoite antigen that forms an important multi-protein complex (RH5/Ripr/CyRPA) necessary for erythrocyte invasion. CyRPA is a promising blood-stage vaccine target that has been shown to elicit potent strain-transcending parasite neutralizing antibodies. Recently, we demonstrated that naturally acquired immune anti-CyRPA antibodies are invasion-inhibitory and therefore a correlate of protection against malaria. Here, we describe a process for the large-scale production of tag-free CyRPA vaccine in E. coli and demonstrate its parasite neutralizing efficacy with commonly used adjuvants. CyRPA was purified from inclusion bodies using a one-step purification method with high purity (>90%). Biochemical and biophysical characterization showed that the purified tag-free CyRPA interacted with RH5, readily detected by a conformation-specific CyRPA monoclonal antibody and recognized by sera from malaria infected individuals thus indicating that the recombinant antigen was correctly folded and retained its native conformation. Tag-free CyRPA formulated with Freund’s adjuvant elicited highly potent parasite neutralizing antibodies achieving inhibition of >90% across diverse parasite strains. Importantly, we identified tag-free CyRPA/Alhydrogel formulation as most effective in inducing a highly immunogenic antibody response that exhibited efficacious, cross-strain in vitro parasite neutralization achieving ~80% at 10 mg/ml. Further, CyRPA/Alhydrogel vaccine induced anti-parasite cytokine response in mice. In summary, our study provides a simple, scalable, cost-effective process for the production of tag-free CyRPA that in combination with human-compatible adjuvant induces efficacious humoral and cell-mediated immune response.