Artemisinin-based combination therapies (ACT) are currently used as a first-line malaria therapy in endemic countries worldwide. This systematic review aims at presenting the current scenario of drug resistance molecular markers, either selected or involved in treatment failures (TF) during in vivo ACT efficacy studies from sub-Saharan Africa (sSA) and India. Eight electronic databases were comprehensively used to search relevant articles and finally a total of 28 studies were included in the review, 21 from sSA and seven from India. On analysis, Artemether + lumefantrine (AL) and artesunate + sulfadoxine-pyrimethamine (AS + SP) are the main ACT in African and Indian regions with a 28-day efficacy range of 54.3-100% for AL and 63-100% for AS + SP respectively. It was observed that mutations in the Pfcrt (76T), Pfdhfr (51I, 59R, 108N), Pfdhps (437G) and Pfmdr1 (86Y, 184F, 1246Y) genes were involved in TF, which varied with respect to ACTs. Based on studies that have genotyped the Pfk13 gene, the reported TF cases, were mainly linked with mutations in genes associated with resistance to ACT partner drugs; indicating that the protection of the partner drug efficacy is crucial for maintaining the efficacy of ACT. This review reveals that ACT are largely efficacious in India and sSA despite the fact that some clinical efficacy and epidemiological studies have reported some validated mutations (i.e., 476I, 539T and 561H) in circulation in these two regions. Also, the role of PfATPase6 in ART resistance is controversial still, while P. falciparum plasmepsin 2 (Pfpm2) in piperaquine (PPQ) resistance and dihydroartemisinin (DHA) + PPQ failures is well documented in Southeast Asian countries but studied less in sSA. Hence, there is a need for continuous molecular surveillance of Pfk13 mutations for emergence of artemisinin (ART) resistance in these countries.

Background: In 2017, nearly 80% of malaria morbidity and mortality occurred in sub-Saharan African (SSA) countries and India. Rapid diagnostic tests (RDTs), especially those targeting histidine-rich protein 2 (PfHRP2) of Plasmodium falciparum, have become an important diagnostic tool in these malaria-endemic areas. However, the chances of RDT-oriented successful treatment are increasingly jeopardized by the appearance of mutants with deletions in pfhrp2 and pfhrp3 genes. This systematic review and meta-analysis determines the prevalence of field P. falciparum isolates with deletion in pfhrp2 and/or pfhrp3 genes and their proportion among false-negative results in the PfHRP2-based RDTs in SSA and India. Methods: Eight electronic databases were used for searching potentially relevant publications for the systematic review analysis, wherein the main methodological aspects of included studies were analysed and some missing links in the included studies were identified. Results: A total of 19 studies were included, 16 from SSA and 3 from India. The pooled prevalence of pfhrp2 deletions was 8 and 5% while 16 and 4% for pfhrp3 gene deletions in Africa and India, respectively. The pooled proportion of pfhrp2 gene deletions found among false negative PfHRP2-based RDTs results was about 27.0 and 69.0% in Africa and India, respectively. Conclusions: This review study indicates a relatively high proportion of both pfhrp2/3 genes deletions in P. falciparum isolates and among false-negative malaria cases using PfHRP2-based RDT results in SSA and India. Recently the deletions in pfhrp2/3 genes have also been reported from two African countries (Nigeria and Sudan). This review emphasizes the importance of more extensive studies and standardization of studies addressing the pfhrp2/3 gene deletions in malarious areas.

Background: Plasmodium vivax, once considered benign species, is recently being recognised to be causing severe malaria like Plasmodium falciparum. In the present study, the authors report the trends in malaria severity in P. vivax among patients from a Delhi government hospital. The aim of the study was to understand the disease severity and the burden of severe vivax malaria. Methods: A hospital based study was carried out from June 2017 to December 2018 at a tertiary care centre from Delhi, India. Patients were tested for malaria using peripheral blood smear (PBS) and/or rapid malaria antigen test (RMAT). The severe and non-severe vivax malaria categorization was done as per the WHO guidelines. Sociodemographic, clinic and paraclinical data were collected from patients and their medical records. Results: Of the 205 patients, 177 (86.3%) had P. vivax infection, 22 (10.7%) had P. falciparum infection and six (2.9%) had mixed infection with both the species. Out of 177 P. vivax cases included in this study one or more manifestations of severe malaria was found in 58 cases (32.7%). Severe anaemia (56.9%), jaundice (15%) and significant bleeding (15%) were the most common complications reported in most of patients, along with thrombocytopenia. Conclusions: In this study, it is evident that vivax malaria is emerging as the new severe disease in malaria patients, a significant shift in the paradigm of P. vivax pathogenesis. The spectrum of complications and alterations in the laboratory parameters in P. vivax clinical cases also indicate the recent shift in the disease severity.

Globally, malaria is a public health concern, with severe malaria (SM) contributing a major share of the disease burden in malaria endemic countries. In this context, identification and validation of SM biomarkers are essential in clinical practice. Some biomarkers (C-reactive protein, angiopoietin 2, angiopoietin-2/1 ratio, platelet count, histidine-rich protein 2) have yielded interesting results in the prognosis of Plasmodium falciparum severe malaria, but for severe P. vivax and P. knowlesi malaria, similar evidence is missing. The validation of these biomarkers is hindered by several factors such as low sample size, paucity of evidence-evaluating studies, suboptimal values of sensitivity/specificity, poor clinical practicality of measurement methods, mixed Plasmodium infections, and good clinical value of the biomarkers for concurrent infections (pneumonia and current COVID-19 pandemic). Most of these biomarkers are non-specific to pathogens as they are related to host response and hence should be regarded as prognostic/predictive biomarkers that complement but do not replace pathogen biomarkers for clinical evaluation of SM patients. This review highlights the importance of research on diagnostic/predictive/therapeutic biomarkers, neglected malaria species, and clinical practicality of measurement methods in future studies. Finally, the importance of omics technologies for faster identification/validation of SM biomarkers is also included.

Recently green nanotechnology has gained great interest as a promising tool for drug discovery. In the present study, we synthesized and characterized silver nanoparticles (AgNPs) using Azadirachta indica (AI) and evaluated their hemocompatibility and effect against Plasmodium falciparum strains. AI leaves and barks were used for aqueous extracts (AIL and AIB) and AgNPs synthesis. AgNPs were characterized using spectroscopic, diffraction, electron microscopic and electrostatic techniques. Anti-plasmodial and haemolytic activity were assessed following the SYBR Green I fluorescence assay and Miki et al. protocol, respectively. The normalized fluorescence counts were plotted against the log-transformed drug concentration and half-maximal inhibitory concentration (IC₅₀) determined by analyzing the dose–response curves. AgNPs were stored for 120 days at room temperature-RT, +4 °C and −20 °C and subsequently their stability was evaluated by spectroscopy. Both NPs were predominantly spheroidal, crystalline in nature, stable, well dispersed with mean size of 13.01 nm for AIL-NPs and 19.30 nm for AIB-NPs and exhibited good antiplasmodial activity against 3D7 and RKL9 P. falciparum strains with IC₅₀ of 9.27 µg/mL and 11.14 µg/mL for AIL-NPs, 8.10 µg/mL and 7.87 µg/mL for AIB-NPs, respectively. A. indica contain bioactive phyto-compounds indicating great potential for anti-malarial drug development through green nanotechnology. The AgNPs were structurally stable after 120 days but antiplasmodial activity was considerably affected. A significant haemolytic activity (>25%) was observed with AIL- and AIB-AgNPs at concentrations ≥125 µg/mL. Graphical Abstract