Human Malaria Research Articles

Potential use of anti-thrombospondin-related apical merozoite protein (TRAMP) polyclonal antibodies in sandwich enzyme-linked immunosorbent assay (ELISA) for detection of Plasmodium knowlesi.

Plasmodium knowlesi, primarily a zoonotic malaria species is the most common malaria pathogen in the Southeast Asia especially in Malaysian Borneo, Malaysia. Due to morphological resemblance of P. knowlesi to other human Plasmodium, the sensitivity for microscopic detection of P. knowlesi, which is the gold standard, is compromised. Thus, efforts have been made in finding alternatives for the disease diagnosis. This study described the potential use of anti-PkTRAMP polyclonal antibodies in sandwich ELISA for P. knowlesi detection. Anti-PkTRAMP polyclonal antibodies raised from mice and rabbit were first evaluated for their binding capability towards native proteins in P. knowlesi lysates using Western blot. These mice and rabbit polyclonal antibodies were then used in the sandwich ELISA as capture and detection antibodies, respectively. P. knowlesi A1H1 culture was utilised to determine the limit of detection (LOD) of this assay. Its clinical performance was determined by testing with archived human malaria and uninfected samples. Western blot analysis affirmed the polyclonal antibodies reactivity to P. knowlesi. The LOD obtained from three replicated assays was at 0.015% parasitaemia. The assay has 76% sensitivity and 75% specificity for P. knowlesi. Its positive and negative predictive values were 76% and 75%, respectively. No cross reactivity with P. falciparum and healthy samples was observed, except for P. vivax where 10 out of 12 samples were detected. In conclusion, anti-PkTRAMP polyclonal antibodies can be useful in detecting P. knowlesi. Regardless, the full potential of anti-PkTRAMP antibodies for diagnostic purposes need to be explored further.

Influence of Altitudinal Gradient on Human Malaria Prevalence in Plateau State, Central Nigeria: A Longitudinal Study

Study’s Excerpt The relationship between altitude and malaria transmission dynamics in Plateau State, North-Central Nigeria, is assessed. The highest malaria prevalence was observed at lower altitudes and vice-versa. Environmental factors (altitude) have an influence on malaria epidemiology in the region. Full Abstract This longitudinal study assessed the prevalence of human malaria infection across different altitudinal zones in Plateau State, North-Central Nigeria, aiming to identify the impact of altitude on malaria transmission dynamics. Malaria is a potentially lethal disease caused by protozoan parasites called Plasmodium. Abiotic factors are known to be the main factors influencing the epidemiology of the disease. In 2018 and 2019, blood samples were taken and examined for the presence of Plasmodium falciparum malaria using the SD-PAN Ag mRDT. After that, blood film slides were created in order to calculate the parasite density for each of the four seasons' worth of positive samples. The prevalence rates of malaria in the three locations vary significantly, with the highest rates observed at lower altitudes (Pangwasa 211m) above sea level and the lowest at the highest altitude (Vwang 1330m) above sea level. Vwang has the lowest malaria prevalence of 16.25%, Jing (663m) has a higher prevalence of 40.0%, and Pangwasa has the highest prevalence at 46.9.

Exploring the Therapeutic Potential of Sphenocentrum jollyanum Root Extract in Malaria Treatment: Efficacy, Safety, and Future Directions

Malaria remains a critical global health challenge, necessitating the exploration of novel therapeutic agents. This review examines the therapeutic potential of the ethanol root-extract of Sphenocentrum jollyanum, a plant traditionally used in West Africa for malaria treatment. Utilizing the Plasmodium berghei rodent model, which mirrors human malaria, we assess the extract’s efficacy in restoring haematological markers, safety profile, and potential as an adjunct or alternative therapy. Sphenocentrum jollyanum, known for its rich phytochemical composition, including alkaloids, flavonoids, saponins, tannins, and terpenoids, has demonstrated significant restorative effects in preliminary studies. The extract improved hemoglobin levels, red blood cell counts, and platelet counts in infected mice, indicating potential benefits in mitigating malaria-induced anemia and other haematological abnormalities. Its mechanisms of action include antioxidant, anti-inflammatory, and immunomodulatory effects. Despite its promising results, rigorous safety evaluations are necessary, including acute and chronic toxicity studies, to ensure its safe use. Future research should focus on clinical trials to validate efficacy, optimize dosage, and explore combination therapies with standard antimalarial drugs. The review emphasizes the need for standardized preparation methods, quality control, and integration into public health strategies to enhance malaria management, particularly in resource-limited regions. Keywords: Sphenocentrum jollyanum Root Extract, Malaria, Treatment, Efficacy, Safety.

Progressive heterogeneity of enlarged and irregularly shaped apicoplasts in Plasmodium falciparum persister blood stages after drug treatment.

Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei are associated with metabolic quiescence of cancer cells that can survive chemotherapy. In plants, changes in the pathways between nuclei, mitochondria, and chloroplasts are associated with cold stress and bud dormancy. Plasmodium falciparum parasites, the deadliest agent of malaria in humans, contain a chloroplast-like organelle (apicoplast) derived from an ancient photosynthetic symbiont. Antimalarial treatments can fail because a fraction of the blood-stage parasites enter dormancy and recrudesce after drug exposure. Altered mitochondrial-nuclear interactions in these persisters have been described for P. falciparum, but interactions of the apicoplast remained to be characterized. In the present study, we examined the apicoplasts of persisters obtained after exposure to dihydroartemisinin (a first-line antimalarial drug) followed by sorbitol treatment, or after exposure to sorbitol treatment alone. As previously observed, the mitochondrion of persisters was consistently enlarged and in close association with the nucleus. In contrast, the apicoplast varied from compact and oblate, like those of active ring-stage parasites, to enlarged and irregularly shaped. Enlarged apicoplasts became more prevalent later in dormancy, but regular size apicoplasts subsequently predominated in actively replicating recrudescent parasites. All three organelles, nucleus, mitochondrion, and apicoplast, became closer during dormancy. Understanding their relationships in erythrocytic-stage persisters may lead to new strategies to prevent recrudescences and protect the future of malaria chemotherapy.

A genome-wide CRISPR screen in Anopheles mosquito cells identifies essential genes and required components of clodronate liposome function.

Anopheles mosquitoes are the sole vector of human malaria, the most burdensome vector-borne disease worldwide. Strategies aimed at reducing mosquito populations and limiting their ability to transmit disease show the most promise for disease control. Therefore, gaining an improved understanding of mosquito biology, and specifically that of the immune response, can aid efforts to develop new approaches that limit malaria transmission. Here, we use a genome-wide CRISPR screening approach for the first time in mosquito cells to identify essential genes in Anopheles and identify genes for which knockout confers resistance to clodronate liposomes, which have been widely used in mammals and arthropods to ablate immune cells. In the essential gene screen, we identified a set of 1280 Anopheles genes that are highly enriched for genes involved in fundamental cell processes. For the clodronate liposome screen, we identified several candidate resistance factors and confirm their roles in the uptake and processing of clodronate liposomes through in vivo validation in Anopheles gambiae, providing new mechanistic detail of phagolysosome formation and clodronate liposome function. In summary, we demonstrate the application of a genome-wide CRISPR knockout platform in a major malaria vector and the identification of genes that are important for fitness and immune-related processes.

A virus associated with the zoonotic pathogen Plasmodium knowlesi causing human malaria is a member of a diverse and unclassified viral taxon.

Apicomplexa are single-celled eukaryotes that can infect humans and include the mosquito-borne parasite Plasmodium, the cause of malaria. Increasing rates of drug resistance in human-only Plasmodium species are reducing the efficacy of control efforts and antimalarial treatments. There are also rising cases of P. knowlesi, the only zoonotic Plasmodium species that causes severe disease and death in humans. Thus, there is a need to develop additional innovative strategies to combat malaria. Viruses that infect non-Plasmodium spp. Disease-causing protozoa have been shown to affect pathogen life cycle and disease outcomes. However, only one virus (Matryoshka RNA virus 1) has been identified in Plasmodium, and none have been identified in zoonotic Plasmodium species. The rapid expansion of the known RNA virosphere using structure- and artificial intelligence-based methods suggests that this dearth is due to the divergent nature of RNA viruses that infect protozoa. We leveraged these newly uncovered data sets to explore the virome of human-infecting Plasmodium species collected in Sabah, east (Borneo) Malaysia. We identified a highly divergent RNA virus in two human-infecting P. knowlesi isolates that is related to the unclassified group 'ormycoviruses'. By characterising fifteen additional ormycoviruses identified in the transcriptomes of arthropods we show that this group of viruses exhibits a complex ecology at the arthropod-mammal interface. Through the application of artificial intelligence methods, we then demonstrate that the ormycoviruses are part of a diverse and unclassified viral taxon. This is the first observation of an RNA virus in a zoonotic Plasmodium species. By linking small-scale experimental data to large-scale virus discovery advances, we characterise the diversity and genomic architecture of an unclassified viral taxon. This approach should be used to further explore the virome of disease-causing Apicomplexa and better understand how protozoa-infecting viruses may affect parasite fitness, pathobiology, and treatment outcomes.

Acetylsalicylic acid and dihydroartemisinin combined therapy on experimental malaria-associated acute lung injury: analysis of lung function and the inflammatory process

BackgroundSevere malaria can cause respiratory symptoms, which may lead to malaria-acute lung injury (MA-ALI) due to inflammation and damage to the blood-gas barrier. Patients with severe malaria also often present thrombocytopenia, and the use of acetylsalicylic acid (ASA), a commonly used non-steroidal anti-inflammatory drug with immunomodulatory and antiplatelet effects, may pose a risk in regions where malaria is endemic. Thus, this study aimed to investigate the systemic impact of ASA and dihydroartemisinin (DHA) on ALI induced in mice by Plasmodium berghei NK65 (PbNK65).MethodsC57BL/6 mice were randomly divided into control (C) and PbNK65 infected groups and were inoculated with uninfected or 104 infected erythrocytes, respectively. Then, the animals were treated with DHA (3 mg/kg) or vehicle (DMSO) at the 8-day post-infection (dpi) for 7 days and with ASA (100 mg/kg, single dose), and analyses were performed at 9 or 15 dpi. Lung mechanics were performed, and lungs were collected for oedema evaluation and histological analyses.ResultsPbNK65 infection led to lung oedema, as well as increased lung static elastance (Est, L), resistive (ΔP1, L) and viscoelastic (ΔP2, L) pressures, percentage of mononuclear cells, inflammatory infiltrate, hemorrhage, alveolar oedema, and alveolar thickening septum at 9 dpi. Mice that received DHA or DHA + ASA had an increase in Est, L, and CD36 expression on inflammatory monocytes and higher protein content on bronchoalveolar fluid (BALF). However, only the DHA-treated group presented a percentage of inflammatory monocytes similar to the control group and a decrease in ΔP1, L and ΔP2, L compared to Pb + DMSO. Also, combined treatment with DHA + ASA led to an impairment in diffuse alveolar damage score and lung function at 9 dpi.ConclusionsTherapy with ASA maintained lung morpho-functional impairment triggered by PbNK65 infection, leading to a large influx of inflammatory monocytes to the lung tissue. Based on its deleterious effects in experimental MA-ALI, ASA administration or its treatment maintenance might be carefully reconsidered and further investigated in human malaria cases.

The Tuberculosis Drug Candidate SQ109 and Its Analogs Have Multistage Activity against Plasmodium falciparum.

Toward repositioning the antitubercular clinical candidate SQ109 as an antimalarial, analogs were investigated for structure-activity relationships for activity against asexual blood stages of the human malaria parasite Plasmodium falciparum pathogenic forms, as well as transmissible, sexual stage gametocytes. We show that equipotent activity (IC50) in the 100-300 nM range could be attained for both asexual and sexual stages, with the activity of most compounds retained against a multidrug-resistant strain. The multistage activity profile relies on high lipophilicity ascribed to the adamantane headgroup, and antiplasmodial activity is critically dependent on the diamine linker. Frontrunner compounds showed conserved activity against genetically diverse southern African clinical isolates. We additionally validated that this series could block transmission to mosquitoes, marking these compounds as novel chemotypes with multistage antiplasmodial activity.

Knowledge, attitude and practice levels regarding malaria among the Semai sub-ethnic indigenous Orang Asli communities in Pahang, Peninsular Malaysia: a stepping stone towards the prevention of human malaria re-establishment

BackgroundIn Malaysia, despite a decline in cases, malaria remains a major public health concern, especially among the vulnerable indigenous people (i.e. Orang Asli) in remote areas. Effective preventive and control measures require an evidence-based understanding of their knowledge, attitudes, and practices (KAP) regarding malaria. This study aimed to evaluate the KAP regarding malaria in an indigenous settlement in Peninsular Malaysia.MethodsA household-based cross-sectional study was conducted in March 2024 in six Semai sub-ethnic indigenous villages in Pos Lenjang, Kuala Lipis, Pahang. A structured questionnaire was administered to randomly selected individuals (≥ 12 years old) to collect data on sociodemographic characteristics and KAP. Data were analysed using descriptive statistics and predictors of KAP were determined using logistic regression. A p-value less than 0.05 was considered statistically significant.ResultsA total of 267 individuals from 160 households were interviewed. Nearly half had good knowledge (49.4%) and positive attitudes (54.3%) towards malaria, with high practice scores for prevention and control (83.1%). Multivariate logistic regression analysis showed higher odds of good knowledge in those aged 40–59 years (adjusted odd ratio [aOR] = 6.90, p = 0.034), with primary (aOR = 2.67, p = 0.015) or secondary education (aOR = 2.75, p = 0.019), and with previous malaria history (aOR = 5.14, p < 0.001). Higher odds of a good attitude were found in those with secondary education (aOR = 4.05, p < 0.001) and previous malaria history (aOR = 2.74, p = 0.017). Lower odds were observed for the unemployed (aOR = 0.25, p = 0.018) and those collecting forest products (aOR = 0.25, p = 0.049) for attitude and practice, respectively.DiscussionThe overall practice level on malaria prevention was high among the Semai Orang Asli in Pahang. However, to ensure sustainability, the low levels of knowledge and attitude regarding malaria must be strengthened through increased health education and continuous community engagement.

Antimalarial drug sulfadoxine induces gametocytogenesis in Plasmodium berghei

BackgroundThe spread of antimalarial drug resistance parasites is a major obstacle in eliminating malaria in endemic areas. This increases the urgency for developing novel antimalarial drugs with improved profiles to eliminate both sensitive and resistant parasites in populations. The invention of the drug candidates needs a model for sensitive and resistant parasites on a laboratory scale.MethodsRepeated Incomplete Treatment (RIcT) method was followed in raising the rodent malaria parasite, Plasmodium berghei, resistant to sulfadoxine. Plasmodium berghei were exposed to an adequate therapeutic dose of sulfadoxine without finishing the treatment to let the parasite recover. Cycles of drug treatment and parasite recovery were repeated until phenotypic resistance appeared.ResultsAfter undergoing 3–4 cycles, phenotypic resistance was not yet found in mice treated with sulfadoxine. Nevertheless, the molecular biology of dhps gene (the target of sulfadoxine) was analyzed at the end of the RIcT cycle. There was no mutations found in the gene target. Interestingly, the appearance of gametocytes at the end of every cycle of drug treatment and parasite recovery was observed. These gametocytes later on would no longer extend their life in the RBC stage, unless mosquitoes bite the infected host. This phenomenon is similar to the case in human malaria infections treated with sulfadoxine-pyrimethamine (SP).ConclusionsIn this study, the antimalarial drug sulfadoxine induced gametocytogenesis in P. berghei, which could raise the risk factor for malaria transmission.

Suppression by RNA Polymerase I Inhibitors Varies Greatly Between Distinct RNA Polymerase I Transcribed Genes in Malaria Parasites.

Transcription of ribosomal RNA (rRNA) by RNA Polymerase I (Pol I) is the rate-limiting step in ribosome biogenesis and a major determinant of cellular growth rates. Unlike virtually every other eukaryote, which express identical rRNA from large tandem arrays of dozens to hundreds of identical rRNA genes in every cell, the genome of the human malaria parasite Plasmodium falciparum contains only a handful single-copy 47S rRNA loci that differ substantially from one another in length, sequence and expression in different cell-types. We found that growth of malaria parasite was acutely sensitive to the Pol I inhibitors 9-hydroxyellipticine and BMH-21 and demonstrate that they greatly reduce the transcription of 47S rRNAs as well as transcription of other non-coding RNA genes. Surprisingly, we found that the various types of Pol I-transcribed genes differed by more than two orders of magnitude in their susceptibility to these inhibitors and explore the implications of these findings for regulation of rRNA in P. falciparum.

Progressive heterogeneity of enlarged and irregularly shaped apicoplasts in P. falciparum persister blood stages after drug treatment.

Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei are associated with metabolic quiescence of cancer cells that can survive chemotherapy. In plants, changes in the pathways between nuclei, mitochondria, and chloroplasts are associated with cold stress and bud dormancy. Plasmodium falciparum parasites, the deadliest agent of malaria in humans, contain a chloroplast-like organelle (apicoplast) derived from an ancient photosynthetic symbiont. Antimalarial treatments can fail because a small fraction of the blood stage parasites enter dormancy and recrudesce after drug exposure. Altered mitochondrial-nuclear interactions in these persisters have been described for P. falciparum, but interactions of the apicoplast remained to be characterized. In the present study, we examined the apicoplasts of persisters obtained after exposure to dihydroartemisinin (a first-line antimalarial drug) followed by sorbitol treatment, or after exposure to sorbitol treatment alone. As previously observed, the mitochondrion of persisters was consistently enlarged and in close association with the nucleus. In contrast, the apicoplast varied from compact and oblate, like those of active ring stage parasites, to enlarged and irregularly shaped. Enlarged apicoplasts became more prevalent later in dormancy, but regular size apicoplasts subsequently predominated in actively replicating recrudescent parasites. All three organelles, nucleus, mitochondrion, and apicoplast, became closer during dormancy. Understanding their relationships in erythrocytic-stage persisters may lead to new strategies to prevent recrudescences and protect the future of malaria chemotherapy.

The artemisinin-induced dormant stages of Plasmodium falciparum exhibit hallmarks of cellular quiescence/senescence and drug resilience

Recrudescent infections with the human malaria parasite, Plasmodium falciparum, presented traditionally the major setback of artemisinin-based monotherapies. Although the introduction of artemisinin combination therapies (ACT) largely solved the problem, the ability of artemisinin to induce dormant parasites still poses an obstacle for current as well as future malaria chemotherapeutics. Here, we use a laboratory model for induction of dormant P. falciparum parasites and characterize their transcriptome, drug sensitivity profile, and cellular ultrastructure. We show that P. falciparum dormancy requires a ~ 5-day maturation process during which the genome-wide gene expression pattern gradually transitions from the ring-like state to a unique form. The transcriptome of the mature dormant stage carries hallmarks of both cellular quiescence and senescence, with downregulation of most cellular functions associated with growth and development and upregulation of selected metabolic functions and DNA repair. Moreover, the P. falciparum dormant stage is considerably more resistant to antimalaria drugs compared to the fast-growing asexual stages. Finally, the irregular cellular ultrastructure further suggests unique properties of this developmental stage of the P. falciparum life cycle that should be taken into consideration by malaria control strategies.

Monoclonal antibodies to the circumsporozoite proteins as an emerging tool for malaria prevention.

Despite various public health strategies, malaria caused by Plasmodium falciparum parasites remains a major global health challenge that requires development of new interventions. Extended half-life human monoclonal antibodies targeting the P. falciparum circumsporozoite protein on sporozoites, the infective form of malaria parasites, prevent malaria in rodents and humans and have been advanced into clinical development. The protective epitopes on the circumsporozoite protein targeted by monoclonal antibodies have been defined. Cryogenic electron and multiphoton microscopy have enabled mechanistic structural and functional investigations of how antibodies bind to the circumsporozoite protein and neutralize sporozoites. Moreover, innovations in bioinformatics and antibody engineering have facilitated enhancement of antibody potency and durability. Here, we summarize the latest scientific advances in understanding how monoclonal antibodies to the circumsporozoite protein prevent malaria and highlight existing clinical data and future plans for how this emerging intervention can be used alone or alongside existing antimalarial interventions to control malaria across at-risk populations.

PfMORC protein regulates chromatin accessibility and transcriptional repression in the human malaria parasite, Plasmodium falciparum.

The environmental challenges the human malaria parasite, Plasmodium falciparum, faces during its progression into its various lifecycle stages warrant the use of effective and highly regulated access to chromatin for transcriptional regulation. Microrchidia (MORC) proteins have been implicated in DNA compaction and gene silencing across plant and animal kingdoms. Accumulating evidence has shed light into the role MORC protein plays as a transcriptional switch in apicomplexan parasites. In this study, using CRISPR/Cas9 genome editing tool along with complementary molecular and genomics approaches, we demonstrate that PfMORC not only modulates chromatin structure and heterochromatin formation throughout the parasite erythrocytic cycle, but is also essential to the parasite survival. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) experiments suggest that PfMORC binds to not only sub-telomeric regions and genes involved in antigenic variation but may also play a role in modulating stage transition. Protein knockdown experiments followed by chromatin conformation capture (Hi-C) studies indicate that downregulation of PfMORC impairs key histone marks and induces the collapse of the parasite heterochromatin structure leading to its death. All together these findings confirm that PfMORC plays a crucial role in chromatin structure and gene regulation, validating this factor as a strong candidate for novel antimalarial strategies.

Antibodies to PfEMP1 and variant surface antigens: Protection after controlled human malaria infection in semi-immune Kenyan adults

Acquisition of antibodies to Plasmodium falciparum variant surface antigens (VSA) expressed on infected red blood cells (iRBCs) is associated with naturally acquired immunity to malaria. We have previously shown that antibodies to VSA on iRBCs are associated with protection against parasite growth in the context of controlled human malaria infection (CHMI). This study explored whether antibodies to recombinant antigens derived from PfEMP1 domains were independently associated with protection during CHMI in semi-immune Kenyan adults. We used a multiplex bead assay to measure levels of IgG antibody against a panel of 27 recombinant PfEMP1 antigens derived from the PfEMP1 repertoire of the 3D7 parasite clone. We measured IgG levels in plasma samples collected from the CHMI participants before inoculation with Sanaria® PfSPZ Challenge, on the day of diagnosis, and 35 days post-inoculation. Univariable and multivariable Cox regression analysis was used to evaluate the relationship between the levels of antibodies to the antigens and CHMI outcome. We also adjusted for previous data including antibodies to VSA on iRBCs, and we assessed the kinetics of antibody acquisition to the different PfEMP1 recombinant antigens over time. All study participants had detectable antibodies to multiple PfEMP1 proteins before inoculation. All PfEMP1 antigens were associated with protection against parasite growth to the threshold criteria for treatment in CHMI, albeit with substantial collinearity. However, individual PfEMP1 antigens were not independently associated with protection following adjustment for breadth of reactivity to VSA on iRBCs and schizont extract. In addition, antibodies to PfEMP1 antigens derived from group B PfEMP1 were induced and sustained in the participants who could not control parasite growth. This study shows that the breadth of antibody response to VSA on iRBCs, and not to specific PfEMP1 antigens, is predictive of protection against malaria in CHMI.

Comparative analysis of treponemal specific chemiluminescence test and rapid card test for screening of syphilis in blood donors – A tertiary center study

Abstract: BACKGROUND: Screening for transfusion-transmitted infections (TTIs) is an important step for the safety of blood transfusion. Major TTIs for which screening is done are hepatitis B surface antigen, antibody to hepatitis B virus, hepatitis C virus, human immunodeficiency virus, syphilis, and malaria. The aim of this study was to compare the diagnostic accuracy of treponemal-specific chemiluminescence test and rapid card test for the screening of syphilis by taking Treponema pallidum hemagglutination assay (TPHA) as a gold standard test. MATERIALS AND METHODS: This was a cross-sectional study. All the routine blood donors were screened according to the National Blood Transfusion Council guidelines. One hundred and twenty syphilis serology-positive samples were obtained either by rapid card test immunochromatographic test/chemiluminescence assay or both. These samples were further tested by TPHA (gold standard test). Statistical analysis was done using the Mcnemar test, DeLong et al. test, and Chi-square test P &lt; 0.05 was considered statistically significant. RESULTS: The sensitivity and specificity of both chemiluminescence and rapid card test were comparable (P &lt; 0.0001) and the diagnostic accuracy of chemiluminescence and rapid card test was 95.83% and 94.58%, respectively. CONCLUSION: Both chemiluminescence and rapid card tests show comparable performance, so it is concluded to use rapid card test as a reliable backup in remote areas, peripheral blood bank setup, and in emergency situations where timesaving is lifesaving.

Advancing spatial repellents for malaria control: effectiveness and cost-effectiveness of a spatial repellent under operational use in Northern Uganda—study protocol for a cluster randomized controlled trial

BackgroundSpatial repellents (SRs) have been widely used for the prevention of mosquito bites, and preliminary findings suggest efficacy against both malaria (1) and Aedes-borne viruses (2) but their effectiveness in reducing mosquito-borne diseases under operational use has never been evaluated. SRs have the potential of being critical tools in the prevention of mosquito-borne diseases in contexts where typical vector control strategies, such as insecticide-treated nets (ITNs) and indoor residual spraying, are inaccessible or underutilized such as among displaced persons or in emergency relief settings.MethodsChildren will be enrolled in 3 separate cohorts to establish the effectiveness of SRs in reducing malaria infection in different distribution channels. One cohort will estimate the direct effect of the SR distributed through a reference channel (study personnel distribution). The two remaining cohorts will estimate the protection of the SR distributed through a voucher channel and the Village Health Team channel. Cohorts will be followed twice a month (approximately every 15 days): during the first scheduled household visit in the month, a blood sample will be taken for malaria rapid diagnostic test (Monthly Visit #1); and, during the second scheduled household visit, a blood sample will only be taken if the participant has a recent history of fever (Monthly Visit #2). The incidence of malaria in each cohort will be estimated and compared to the reference cohort to determine the benefit of using a SR in an area with high, year-round transmission of malaria.DiscussionThis study will address the knowledge gap of whether or not SRs are effective in reducing human malaria disease in humanitarian assistance and emergency response settings in sub-Saharan Africa where underlying transmission rates are historically high and ITNs may or may not be widely deployed. This research will inform policy makers on whether to recommend SRs as a means to further reduce malaria transmission for such operational programs.Trial registrationClinicalTrials.gov NCT06122142. Registered on November 8, 2023.

Moving population is a challenge for malaria elimination in India: A cross-sectional study to assess malaria parasite infections in walking pilgrims in western Rajasthan, India

ObjectivesIndia is vigorously pursuing malaria elimination by 2030 and one of the key challenges is how to prevent the malaria risk associated with long-distance migrations of populations from endemic to non-endemic areas. Millions of pilgrims walking to the holy Ramdevra temple stay in temporary shelters along the route in district of Jaisalmer, Rajasthan state in western India. The main pilgrimage period coincides with the post-monsoon period with elevated vector densities. We investigated this situation to assess the potential risk posed by migrant pilgrims along the four highways in the temple district in disseminating malaria infections associated with their annual movements. MethodsA cross-sectional study was conducted for screening malaria in walking pilgrims from neighboring states at selected sites and a follow-up study for screening residents in Rajasthan from 2021 to 2023. The study comprises state entry routes, Ramdevra shrine, and pilgrimage route villages situated in western Rajasthan. Epidemiologic and entomologic surveillance was conducted during the “fair” period (August-September) and in pilgrimage route villages in three different seasons of the year to assess malaria in humans and the vector's infectivity. ResultsOf the 5251 individuals tested for malaria, a total of 76 (1.4%) tested positive for malaria, of whom 40.7% were infected with Plasmodium vivax (n = 31), 36.8% with P. falciparum (n = 28), and 22.3% with P. vivax and P. falciparum (n = 17). Anopheles density was highest during the fair season, peaking in August. An. stephensi exhibited a higher human blood index (0.65) than An. culicifacies (0.50). No mosquitoes were found positive for parasites. ConclusionsUp to 1.5% of pilgrims carried malaria parasites, posing a risk of spreading malaria to surrounding communities that otherwise would have low or no malaria burden. Moving populations pose the risk of local malaria transmission and reintroduction to the areas undergoing elimination. Sentinel point surveillance at the border of states will be helpful for states to share information on malaria and subsequently for the prevention of malaria transmission.

Chemoproteomic Strategy Identifies PfUCHL3 as the Target of Halofuginone.

The human malaria parasite Plasmodium falciparum (P. falciparum) continues to pose a significant public health challenge, leading to millions of fatalities globally. Halofuginone (HF) has shown a significant anti-P. falciparum effect, suggesting its potential as a therapeutic agent for malaria treatment. In this study, we synthesized a photoaffinity labeling probe of HF to identify its direct target in P. falciparum. Our results reveal that ubiquitin carboxyl-terminal hydrolase 3 (PfUCHL3) acts as a crucial target protein of HF, which modulates parasite growth in the intraerythrocytic cycle. In particular, we discovered that HF potentially forms hydrogen bonds with the Leu10, Glu11, and Arg217 sites of PfUCHL3, thereby inducing an allosteric effect by promoting the embedding of the helix 6' region on the protein surface. Furthermore, HF disrupts the expression of multiple functional proteins mediated by PfUCHL3, specifically those that play crucial roles in amino acid biosynthesis and metabolism in P. falciparum. Taken together, this study highlights PfUCHL3 as a previously undisclosed druggable target of HF, which contributes to the development of novel anti-malarial agents in the future.