Real-time PCR for malaria diagnosis and identification of Plasmodium species in febrile patients in Cubal, Angola.

BACKGROUND: Malaria is the parasitic disease with the highest morbimortality worldwide. The World Health Organization (WHO) estimates that there were approximately 249 million cases in 2022, of which 3.4% were in Angola. Diagnosis is based on parasite identification by microscopy examination, antigen detection, and/or molecular tests, such as polymerase chain reaction (PCR). This study aimed to evaluate the usefulness of real-time PCR as a diagnostic method for malaria in an endemic area (Cubal, Angola). METHODS: A cross-sectional study was carried out at the Hospital Nossa Senhora da Paz in Cubal, Angola, including 200 patients who consulted for febrile syndrome between May and July 2022. From each patient, a capillary blood sample was obtained by finger prick for malaria field diagnosis [microscopy and rapid diagnostic test (RDT)] and venous blood sample for real-time PCR performed at the Hospital Universitario Vall d'Hebron in Barcelona, Spain. Any participant with a positive result from at least one of these three methods was diagnosed with malaria. RESULTS: Of the 200 participants included, 54% were female and the median age was 7 years. Malaria was diagnosed by at least one of the three techniques (microscopy, RDT, and/or real-time PCR) in 58% of the participants, with RDT having the highest percentage of positivity (49%), followed by real-time PCR (39.5%) and microscopy (33.5%). Of the 61 discordant samples, 4 were only positive by microscopy, 13 by real-time PCR, and 26 by RDT. Plasmodium falciparum was the most frequent species detected (90.63%), followed by P. malariae (17.19%) and P. ovale (9.38%). Coinfections were detected in ten participants (15.63%): six (60%) were caused by P. falciparum and P. malariae, three (30%) by P. falciparum and P. ovale, and one (10%) triple infection with these three species. In addition, it was observed that P. falciparum and P. malariae coinfection significantly increased the parasite density of the latter. CONCLUSIONS: RDT was the technique with the highest positivity rate, followed by real-time PCR and microscopy. The results of the real-time PCR may have been underestimated due to suboptimal storage conditions during the transportation of the DNA eluates. However, real-time PCR techniques have an important role in the surveillance of circulating Plasmodium species, given the epidemiological importance of the increase in non-falciparum species in the country, and can provide an estimate of the intensity of infection.

Does host migration affect host-parasite interaction? Migrant birds harbor exclusive parasites but have similar roles in parasite-host networks.

Parasites comprise a substantial portion of global biodiversity and play critical roles in shaping ecosystems by modulating trophic networks and affecting their hosts' abundance and distribution. The dynamics of host migration introduce new complexity to these relationships. From the host perspective, migratory behavior can either act as a defense mechanism or augment exposure to a broader spectrum of pathogens. Conversely, for parasites, host migration represents a mechanism for their dispersion and an opportunity to infect new host species. This study investigates the complex interplay between migration and parasite-host interactions, focusing on the interaction between hosts and avian malaria and malaria-like parasites in the Brazilian Atlantic Rain Forest. We captured 1466 birds representing 70 different species, uncovering 322 infections with Plasmodium/Haemoproteus parasites. We observed variations in migration timing and fluctuations in host abundance across months. By comparing the observed patterns of interaction of migratory and non-migratory birds to patterns of interaction expected at random, we show that migration affects the roles hosts take in the parasite-host network. Interestingly, despite the fact migratory species hosted more exclusive and distinct parasites, migrants did not occupy central network positions, which are mostly occupied by resident birds. Overall, we highlight the role of resident birds as a key species within parasite-host communities and the high specialization among avian haemosporidians and their hosts.

Validation of real-time PCR assays for detecting Plasmodium and Babesia DNA species in blood samples.

Malaria and babesiosis are global health threats affecting humans, wildlife, and domestic animals, particularly in Africa, the Americas, and Europe. Malaria can lead to severe outcomes, while babesiosis usually resembles a mild illness but can be severe and fatal in individuals with weakened immune systems. Swift, accurate detection of these parasites is crucial for treatment and control. We evaluated a real-time PCR assay for diagnosing five Plasmodium and three Babesia species from blood samples, assessing its sensitivity, specificity, and analytical performance by analyzing 46 malaria-positive and 32 Babesia spp-positive samples diagnosed through microscopy. The limit of detection for Plasmodium species ranged from 30 to 0.0003 copies/µL. For mixed infections, it was 0.3 copies/µL for P. falciparum/P. vivax and 3 copies/µL for P. malariae/P. knowlesi. Babesia species had a detection limit of 0.2 copies/µL. No cross-reactivity was observed among 64 DNA samples from various microorganisms. The assay showed good sensitivity, detecting Plasmodium and Babesia species with 100 % accuracy overall, except for P. falciparum (97.7 %) and B. microti (12.5 %). The low sensitivity of detecting B. microti was attributed to limitations in microscopy for species identification. This technique heavily relies on the proficiency of the examiner, as species within the genus cannot be distinguished under a microscope. Additionally, Babesia can be confused with the early trophozoite stage (ring forms) of Plasmodium parasites. The findings support multiplex qPCR's diagnostic superiority over the gold standard, despite higher costs. It offers enhanced sensitivity, specificity, and detects mixed infections, crucial for effective monitoring and diagnosis of malaria and babesiosis in endemic regions with significant public health challenges.

MalariaFlow: A comprehensive deep learning platform for multistage phenotypic antimalarial drug discovery.

Malaria remains a significant global health challenge due to the growing drug resistance of Plasmodium parasites and the failure to block transmission within human host. While machine learning (ML) and deep learning (DL) methods have shown promise in accelerating antimalarial drug discovery, the performance of deep learning models based on molecular graph and other co-representation approaches warrants further exploration. Current research has overlooked mutant strains of the malaria parasite with varying degrees of sensitivity or resistance, and has not covered the prediction of inhibitory activities across the three major life cycle stages (liver, asexual blood, and gametocyte) within the human host, which is crucial for both treatment and transmission blocking. In this study, we manually curated a benchmark antimalarial activity dataset comprising 407,404 unique compounds and 410,654 bioactivity data points across ten Plasmodium phenotypes and three stages. The performance was systematically compared among two fingerprint-based ML models (RF::Morgan and XGBoost:Morgan), four graph-based DL models (GCN, GAT, MPNN, and Attentive FP), and three co-representations DL models (FP-GNN, HiGNN, and FG-BERT), which reveal that: 1) The FP-GNN model achieved the best predictive performance, outperforming the other methods in distinguishing active and inactive compounds across balanced, more positive, and more negative datasets, with an overall AUROC of 0.900; 2) Fingerprint-based ML models outperformed graph-based DL models on large datasets (>1000 compounds), but the three co-representations DL models were able to incorporate domain-specific chemical knowledge to bridge this gap, achieving better predictive performance. These findings provide valuable guidance for selecting appropriate ML and DL methods for antimalarial activity prediction tasks. The interpretability analysis of the FP-GNN model revealed its ability to accurately capture the key structural features responsible for the liver- and blood-stage activities of the known antimalarial drug atovaquone. Finally, we developed a web server, MalariaFlow, incorporating these high-quality models for antimalarial activity prediction, virtual screening, and similarity search, successfully predicting novel triple-stage antimalarial hits validated through experimental testing, demonstrating its effectiveness and value in discovering potential multistage antimalarial drug candidates.

A broadly cross-reactive i-body to AMA1 potently inhibits blood and liver stages of Plasmodium parasites.

Apical membrane antigen-1 (AMA1) is a conserved malarial vaccine candidate essential for the formation of tight junctions with the rhoptry neck protein (RON) complex, enabling Plasmodium parasites to invade human erythrocytes, hepatocytes, and mosquito salivary glands. Despite its critical role, extensive surface polymorphisms in AMA1 have led to strain-specific protection, limiting the success of AMA1-based interventions beyond initial clinical trials. Here, we identify an i-body, a humanised single-domain antibody-like molecule that recognises a conserved pan-species conformational epitope in AMA1 with low nanomolar affinity and inhibits the binding of the RON2 ligand to AMA1. Structural characterisation indicates that the WD34 i-body epitope spans the centre of the conserved hydrophobic cleft in AMA1, where interacting residues are highly conserved among all Plasmodium species. Furthermore, we show that WD34 inhibits merozoite invasion of erythrocytes by multiple Plasmodium species and hepatocyte invasion by P. falciparum sporozoites. Despite a short half-life in mouse serum, we demonstrate that WD34 transiently suppressed P. berghei infections in female BALB/c mice. Our work describes the first pan-species AMA1 biologic with inhibitory activity against multiple life-cycle stages of Plasmodium. With improved pharmacokinetic characteristics, WD34 could be a potential immunotherapy against multiple species of Plasmodium.

Mosquito prevalence, resting habitat preference, and Plasmodium infection status of anophelines in coastal Karnataka during the declining phase of malaria-an exploratory study.

Malaria has a historical presence in the Dakshina Kannada (D.K.) and Udupi districts of Karnataka, India. To understand the potential involvement of anopheline fauna in malaria transmission, we conducted an exploratory entomological survey. The study is crucial given the decreasing malaria incidence in these districts in recent years. From September 2022 to August 2023, we collected indoor resting mosquitoes using a manual aspirator at 27 randomly chosen sites within three distinct resting habitats (human dwellings, cattle sheds, and construction sites) in the urban areas of Udupi and Dakshina Kannada districts. Mosquitoes were morphologically identified, and anopheline specimens were tested for the presence of malarial parasite by polymerase chain reaction (PCR) analysis. We collected a total of 1810 mosquitoes, comprising 21 species distributed across five genera. Culex emerged as the predominant genus, constituting 84.4% of the collected specimens, while Anopheles accounted for 5.4%. Among the observed species, Culex quinquefasciatus was predominant, comprising 77.9% of the mosquito specimens collected in this study. Two malaria vectors, An. stephensi and An. subpictus complex, constituted 16.3% and 1.0% of the total anophelines collected, respectively. None of the 96 female anophelines was tested positive for Plasmodium infection. Our findings suggest that Anopheles mosquitoes prefer resting in cattle sheds over human dwellings. While our study identified two malaria vectors, they were present at low densities. To gain a more comprehensive understanding of the dynamics of these vector mosquitoes, it is essential to conduct long-term surveillance to monitor their prevalence and role in malaria transmission.

Malaria screening: what is the contribution of molecular biology?

INTRODUCTION: According to the World Health Organization, Microscopy is the gold standard for diagnosing malaria. However, the performance of this examination depends on the experience of the microscopist and the level of parasitemia. Thus, molecular biology detection of malaria could be an alternative technique. AIM: evaluate the contribution of molecular biology in detecting imported malaria. METHODS: This was a descriptive, prospective study, including all students, from the Monastir region, and foreigners, from countries endemic to malaria. The study period was from September 2020 to April 2021. Each subject was screened for malaria by three methods: direct microscopic detection of Plasmodium, detection of plasmodial antigens, and detection of plasmodial DNA by nested PCR. RESULTS: Among the 127 subjects screened, only one had a positive microscopic examination for Plasmodium falciparum. Among the 126 subjects with a negative microscopic examination, twelve students had a positive nested PCR result, i.e. 9.5%. Molecular sequencing allowed the identification of ten isolates of Plasmodium falciparum, one Plasmodium malariae and one Plasmodium ovale. Our study showed that the results of nested PCR agreed with those of microscopy in 90.6% of cases. CONCLUSION: Nested PCR seems more sensitive for the detection of low parasitemias. Hence the importance of including molecular biology as a malaria screening tool to ensure better detection of imported cases.

Image cropping for malaria parasite detection on heterogeneous data.

Malaria is a deadly disease of significant concern for the international community. It is an infectious disease caused by a Plasmodium spp. parasite and transmitted by the bite of an infected female Anopheles mosquito. The parasite multiplies in the liver and then destroys the person's red blood cells until it reaches the severe stage, leading to death. The most used tools for diagnosing this disease are the microscope and the rapid diagnostic test (RDT), which have limitations preventing control of the disease. Computer vision technologies present alternatives by providing the means for early detection of this disease before it reaches the severe stage, facilitating treatment and saving patients. In this article, we suggest deep learning methods for earlier and more accurate detection of malaria parasites with high generalization capabilities using microscopic images of blood smears from many heterogeneous patients. These techniques are based on an image preprocessing method that mitigates some of the challenges associated with the variety of red cell characteristics due to patient diversity and other artifacts present in the data. For the study, we collected 65,970 microscopic images from 876 different patients to form a dataset of 33,007 images with a variety that enables us to create models with a high level of generalization. Three types of convolutional neural networks were used, namely Convolutional Neural Network (CNN), DenseNet, and LeNet-5, and the highest classification accuracy on the test data was 97.50% found with the DenseNet model.

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.

A transfer learning approach to identify Plasmodium in microscopic images.

Plasmodium parasites cause Malaria disease, which remains a significant threat to global health, affecting 200 million people and causing 400,000 deaths yearly. Plasmodium falciparum and Plasmodium vivax remain the two main malaria species affecting humans. Identifying the malaria disease in blood smears requires years of expertise, even for highly trained specialists. Literature studies have been coping with the automatic identification and classification of malaria. However, several points must be addressed and investigated so these automatic methods can be used clinically in a Computer-aided Diagnosis (CAD) scenario. In this work, we assess the transfer learning approach by using well-known pre-trained deep learning architectures. We considered a database with 6222 Region of Interest (ROI), of which 6002 are from the Broad Bioimage Benchmark Collection (BBBC), and 220 were acquired locally by us at Fundação Oswaldo Cruz (FIOCRUZ) in Porto Velho Velho, Rondônia-Brazil, which is part of the legal Amazon. We exhaustively cross-validated the dataset using 100 distinct partitions with 80% train and 20% test for each considering circular ROIs (rough segmentation). Our experimental results show that DenseNet201 has a potential to identify Plasmodium parasites in ROIs (infected or uninfected) of microscopic images, achieving 99.41% AUC with a fast processing time. We further validated our results, showing that DenseNet201 was significantly better (99% confidence interval) than the other networks considered in the experiment. Our results support claiming that transfer learning with texture features potentially differentiates subjects with malaria, spotting those with Plasmodium even in Leukocytes images, which is a challenge. In Future work, we intend scale our approach by adding more data and developing a friendly user interface for CAD use. We aim at aiding the worldwide population and our local natives living nearby the legal Amazon's rivers.

Transinfection of Wolbachia wAlbB into Culex quinquefasciatus mosquitoes does not alter vector competence for Hawaiian avian malaria (Plasmodium relictum GRW4).

Avian malaria is expanding upslope with warmer temperatures and driving multiple species of Hawaiian birds towards extinction. Methods to reduce malaria transmission are urgently needed to prevent further declines. Releasing Wolbachia-infected incompatible male mosquitoes could suppress mosquito populations and releasing Wolbachia-infected female mosquitoes (or both sexes) could reduce pathogen transmission if the Wolbachia strain reduced vector competence. We cleared Culex quinquefasciatus of their natural Wolbachia pipientis wPip infection and transinfected them with Wolbachia wAlbB isolated from Aedes albopictus. We show that wAlbB infection was transmitted transovarially, and demonstrate cytoplasmic incompatibility with wild-type mosquitoes infected with wPip from Oahu and Maui, Hawaii. We measured vector competence for avian malaria, Plasmodium relictum, lineage GRW4, of seven mosquito lines (two with wAlbB; three with natural wPip infection, and two cleared of Wolbachia infection) by allowing them to feed on canaries infected with recently collected field isolates of Hawaiian P. relictum. We tested 73 groups (Ntotal = 1176) of mosquitoes for P. relictum infection in abdomens and thoraxes 6-14 days after feeding on a range of parasitemias from 0.028% to 2.49%, as well as a smaller subset of salivary glands. We found no measurable effect of Wolbachia on any endpoint, but strong effects of parasitemia, days post feeding, and mosquito strain on both abdomen and thorax infection prevalence. These results suggest that releasing male wAlbB-infected C. quinquefasciatus mosquitoes could suppress wPip-infected mosquito populations, but would have little positive or negative impact on mosquito vector competence for P. relictum if wAlbB became established in local mosquito populations. More broadly, the lack of Wolbachia effects on vector competence we observed highlights the variable impacts of both native and transinfected Wolbachia infections in mosquitoes.

Endocytosis in malaria parasites: An ultrastructural perspective of membrane interplay in a unique infection model.

Malaria remains a major global threat, representing a severe public health problem worldwide. Annually, it is responsible for a high rate of morbidity and mortality in many tropical developing countries where the disease is endemic. The causative agent of malaria, Plasmodium spp., exhibits a complex life cycle, alternating between an invertebrate vector, which transmits the disease, and the vertebrate host. The disease pathology observed in the vertebrate host is attributed to the asexual development of Plasmodium spp. inside the erythrocyte. Once inside the red blood cell, malaria parasites cause extensive changes in the host cell, increasing membrane rigidity and altering its normal discoid shape. Additionally, during their intraerythrocytic development, malaria parasites incorporate and degrade up to 70 % of host cell hemoglobin. This mechanism is essential for parasite development and represents an important drug target. Blocking the steps related to hemoglobin endocytosis or degradation impairs parasite development and can lead to its death. The ultrastructural analysis of hemoglobin endocytosis on Plasmodium spp. has been broadly explored along the years. However, it is only recently that the proteins involved in this process have started to emerge. Here, we will review the most important features related to hemoglobin endocytosis and catabolism on malaria parasites. A special focus will be given to the recent analysis obtained through 3D visualization approaches and to the molecules involved in these mechanisms.

A Pan Plasmodium lateral flow recombinase polymerase amplification assay for monitoring malaria parasites in vectors and human populations.

Robust diagnostic tools and surveillance are crucial for malaria control and elimination efforts. Malaria caused by neglected Plasmodium parasites is often underestimated due to the lack of rapid diagnostic tools that can accurately detect these species. While nucleic-acid amplification technologies stand out as the most sensitive methods for detecting and confirming Plasmodium species, their implementation in resource-constrained settings poses significant challenges. Here, we present a Pan Plasmodium recombinase polymerase amplification lateral flow (RPA-LF) assay, capable of detecting all six human infecting Plasmodium species in low resource settings. The Pan Plasmodium RPA-LF assay successfully detected low density clinical infections with a preliminary limit of detection between 10-100 fg/µl for P. falciparum. When combined with crude nucleic acid extraction, the assay can serve as a point-of-need tool for molecular xenomonitoring. This utility was demonstrated by screening laboratory-reared Anopheles stephensi mosquitoes fed with Plasmodium-infected blood, as well as field samples of An. funestus s.l. and An. gambiae s.l. collected from central Africa. Overall, our proof-of-concept Pan Plasmodium diagnostic tool has the potential to be applied for clinical and xenomonitoring field surveillance, and after further evaluation, could become an essential tool to assist malaria control and elimination.

Gene expression analysis of Anopheles Meigen, 1818 (Diptera: Culicidae) innate immunity after Plasmodium Marchiafava & Celli, 1885 (Apicomplexa) infection: Toward developing new malaria control strategies.

Despite the critical role of the Anopheles innate immune system in defending against Plasmodium infection, there is still limited information about the key immune mechanisms in Anopheles. This review assesses recent findings on the expression characteristics of immune-related genes in Anopheles following exposure to Plasmodium. A literature review, unrestricted by publication date, was conducted to evaluate immune-related gene expression in different organs of Anopheles after Plasmodium infection. Mosquito immune responses in the midgut are essential for reducing parasite populations. Additionally, innate immune responses in the salivary glands and hemocytes circulating in the hemocoel play key roles in defense against the parasite. Transcriptomic analysis of the mosquito's innate immune response to Plasmodium infection provides valuable insights into key immune mechanisms in mosquito defense. A deeper understanding of immune mechanisms in different organs of Anopheles following Plasmodium infection will aid in discovering critical targets for designing novel control strategies.

Genomic variation in Plasmodium relictum (lineage SGS1) and its implications for avian malaria infection outcomes: insights from experimental infections and genome-wide analysis.

BACKGROUND: The globally transmitted avian malaria parasite Plasmodium relictum (lineage SGS1) has been found to infect hundreds of different bird species with differences in infection outcomes ranging from more or less latent to potentially mortal. However, to date basic knowledge about the links between genetic differentiation and variation in infection outcome within this single malaria parasite species is lacking. METHODS: In this study, two different isolates of SGS1, obtained in the wild from two different host species, were used to investigate differences in their development in the blood and virulence in the experimentally infected canaries. Simultaneously, 258 kb of the parasite genome was screened for genetic differences using parasite mRNA and compared between experimental groups. RESULTS: The two isolates showed differences in development and caused mortality as well as effects on the blood parameters of their hosts. Although previous studies using single genes have shown very limited within lineage genetic diversity in the European population of SGS1, 226 SNPs were found across 322 genes, which separated the two experimental groups with a total of 23 SNPs that were fixed in either of the experimental groups. Moreover, genetic variation was found within each experimental group, hinting that each avian malaria infection harbours standing genetic variation that might be selected during each individual infection episode. CONCLUSION: These results highlight extensive genetic variation within the SGS1 population that is transferred into individual infections, thus adding to the complexity of the infection dynamics seen in these host-parasite interactions. Simultaneously, the results open up the possibility of understanding how genetic variation within the parasite populations is linked to the commonly observed differences in infection outcomes, both in experimental settings and in the wild.

Plasmodium gametocyte carriage in humans and sporozoite rate in anopheline mosquitoes in Gondar zuria district, Northwest Ethiopia.

Although the overall burden of malaria is decreasing in Ethiopia, a recent report of an unpredictable increased incidence may be related to the presence of community-wide gametocyte-carrier individuals and a high proportion of infected vectors. This study aimed to reveal the current prevalence of gametocyte-carriage and the sporozoite infectivity rate of Anopheles vectors for Plasmodium parasites. A community-based cross-sectional study was conducted from May 01 to June 30/2019. A total of 53 households were selected using systematic random sampling and a 242 study participants were recruited. Additionally,515 adult female Anopheles mosquitoes were collected using Center for Diseases Control and Prevention (CDC) light traps and mouth aspirators. Parasite gametocytemia was determined using giemsa stain microscopy, while sporozoite infection was determined by giemsa staining microscopy and enzyme linked immunosorbent assay (ELISA). Among the total 242 study participants, 5.4% (95%, CI = 2.9-8.3) of them were positive for any of the Plasmodium species gametocyte. Furthermore, being female [AOR = 15.5(95%, CI = 1.71-140.39)], age group between 15-29 years old [AOR = 16.914 (95%, CI = 1.781-160.63)], no ITNs utilization [AOR = 16.7(95%, CI = 1.902 -146.727)], and high asexual parasite density [(95%, CI = 0.057-0.176, P = 0.001, F = 18.402)] were identified as statistically significant factors for gametocyte carriage. Whereas sporozoite infection rate was 11.6% (95%, CI = 8.2-15.5) and 12.7% (95%, CI = 9.6-16.3) by microscopy and ELISA, respectively. Overall, this study indicated that malaria remains to be an important public health problem in Gondar Zuria district where high gametocyte carriage rate and sporozoite infection rate could sustain its transmission and burden. Therefore, in Ethiopia, where malaria elimination program is underway, frequent, and active community-based surveillance of gametocytemia and sporozoite infection rate is important.

Elevated Inflammation Associated with Markers of Neutrophil Function and Gastrointestinal Disruption in Pilot Study of Plasmodium fragile Co-Infection of ART-Treated SIVmac239+ Rhesus Macaques.

Human immunodeficiency virus (HIV) and malaria, caused by infection with Plasmodium spp., are endemic in similar geographical locations. As a result, there is high potential for HIV/Plasmodium co-infection, which increases the pathology of both diseases. However, the immunological mechanisms underlying the exacerbated disease pathology observed in co-infected individuals are poorly understood. Moreover, there is limited data available on the impact of Plasmodium co-infection on antiretroviral (ART)-treated HIV infection. Here, we used the rhesus macaque (RM) model to conduct a pilot study to establish a model of Plasmodium fragile co-infection during ART-treated simian immunodeficiency virus (SIV) infection, and to begin to characterize the immunopathogenic effect of co-infection in the context of ART. We observed that P. fragile co-infection resulted in parasitemia and anemia, as well as persistently detectable viral loads (VLs) and decreased absolute CD4+ T-cell counts despite daily ART treatment. Notably, P. fragile co-infection was associated with increased levels of inflammatory cytokines, including monocyte chemoattractant protein 1 (MCP-1). P. fragile co-infection was also associated with increased levels of neutrophil elastase, a plasma marker of neutrophil extracellular trap (NET) formation, but significant decreases in markers of neutrophil degranulation, potentially indicating a shift in the neutrophil functionality during co-infection. Finally, we characterized the levels of plasma markers of gastrointestinal (GI) barrier permeability and microbial translocation and observed significant correlations between indicators of GI dysfunction, clinical markers of SIV and Plasmodium infection, and neutrophil frequency and function. Taken together, these pilot data verify the utility of using the RM model to examine ART-treated SIV/P. fragile co-infection, and indicate that neutrophil-driven inflammation and GI dysfunction may underlie heightened SIV/P. fragile co-infection pathogenesis.

Melatonin as a Circadian Marker for Plasmodium Rhythms.

Plasmodium, a digenetic parasite, requires a host and a vector for its life cycle completion. Most Plasmodium species display circadian rhythmicity during their intraerythrocytic cycle within the host, aiding in immune evasion. This rhythmicity, however, diminishes in in vitro cultures, highlighting the importance of host-derived signals for synchronizing the parasite's asexual cycle. Studies indicate a species-specific internal clock in Plasmodium, dependent on these host signals. Melatonin, a hormone the pineal gland produces under circadian regulation, impacts various physiological functions and is extensively reviewed as the primary circadian marker affecting parasite rhythms. Research suggests that melatonin facilitates synchronization through the PLC-IP3 signaling pathway, activating phospholipase C, which triggers intracellular calcium release and gene expression modulation. This evidence strongly supports the role of melatonin as a key circadian marker for parasite synchronization, presenting new possibilities for targeting the melatonin pathway when developing novel therapeutic approaches.

A geometrical theory of gliding motility based on cell shape and surface flow.

Gliding motility proceeds with little changes in cell shape and often results from actively driven surface flows of adhesins binding to the extracellular environment. It allows for fast movement over surfaces or through tissue, especially for the eukaryotic parasites from the phylum apicomplexa, which includes the causative agents of the widespread diseases malaria and toxoplasmosis. We have developed a fully three-dimensional active particle theory which connects the self-organized, actively driven surface flow over a fixed cell shape to the resulting global motility patterns. Our analytical solutions and numerical simulations show that straight motion without rotation is unstable for simple shapes and that straight cell shapes tend to lead to pure rotations. This suggests that the curved shapes of Plasmodium sporozoites and Toxoplasma tachyzoites are evolutionary adaptations to avoid rotations without translation. Gliding motility is also used by certain myxo- or flavobacteria, which predominantly move on flat external surfaces and with higher control of cell surface flow through internal tracks. We extend our theory for these cases. We again find a competition between rotation and translation and predict the effect of internal track geometry on overall forward speed. While specific mechanisms might vary across species, in general, our geometrical theory predicts and explains the rotational, circular, and helical trajectories which are commonly observed for microgliders. Our theory could also be used to design synthetic microgliders.

A breath of fresh air: impact of insect-borne protozoan parasites on the respiratory system.

The protozoan parasites Plasmodium, Leishmania, and Trypanosoma are transmitted by hematophagous insects and cause severe diseases in humans. These infections pose a global threat, particularly in low-resource settings, and are increasingly extending beyond the current endemic regions. Tropism of parasites is crucial for their development, and recent studies have revealed colonization of noncanonical tissues, aiding their survival and immune evasion. Despite receiving limited attention, cumulative evidence discloses the respiratory system as a significant interface for host-pathogen interactions, influencing the course of (co)infection and disease onset. Due to its pathophysiological and clinical implications, we emphasize that further research is needed to better understand the involvement of the respiratory system and its potential to improve prevention, diagnosis, treatment, and interruption of the chain of transmission.