Sandra Fankem Noukimi

Malaria is a major public health challenge in low- and middle-income countries with significant socio-economic impacts. While chemotherapy has greatly contributed to malaria control, the widespread emergence of resistance to antimalarial drugs threatens progress towards elimination goals. In parallel, the recent rollout of the RTS,S/AS01 and R21/Matrix-M malaria vaccine—targeting the Plasmodium falciparum circumsporozoite protein (CSP)—offers a new prevention tool but may be influenced by parasite genetic diversity. This study investigated the genetic architecture of Plasmodium falciparum circulating in a community in the Southwest Region of Cameroon. Seventy-two blood samples were analyzed using targeted Oxford Nanopore sequencing of pfcrt, pfmdr1, pfdhfr, pfdhps, pfkelch13 and pfcsp genes. We observed a high prevalence of pfdhfr mutations (98.6% N51I, 98.6% C59R, 97.7% S108N) and pfmdr1 Y184F (76.1%) mutation. Mutations in pfdhps (54.2% S436A, 2.8% A437G, 38.9% A581G) were also observed. No WHO-validated pfkelch13 artemisinin resistance markers were found; however, K189T (63.4%) and R255K (4.2%) variants were detected. Nineteen non-synonymous SNPs were identified in pfcsp, reflecting natural background variations as vaccination status was not known. These findings support the continued use of artemisinin-based combination therapies and underscores the need for sustained molecular surveillance of both antimalarial drug resistance and vaccine-related polymorphisms, to inform malaria control strategies.

Artemisinin-based combination therapies (ACTs) remain the cornerstone of malaria treatment in Rwanda, but the emergence of drug resistance threatens their efficacy. This study conducted genomic surveillance of Plasmodium falciparum isolates collected in Kigali between October 2021 and June 2023 to assess resistance markers. Using Oxford Nanopore Technology and Sanger sequencing methods, we analyzed 250 clinical isolates focusing on mutations in the pfcrt, pfmdr1, pfdhfr, pfdhps, and Pfkelch13 genes. Resistance-associated mutations were highly prevalent: pfcrt 76T (26%) and pfmdr1 184F (72.8%) were common, indicating continued lumefantrine pressure. All isolates carried mutations in pfdhfr and pfdhps, with the IRNI-SAEAA and IRNI-SAEGA haplotypes found in 45.6% and 24.8% of samples, respectively, suggesting sustained antifolate resistance. Pfkelch13 mutations were present in 50.4% of isolates, including validated R561H (25.6%), A675V and candidate P441L mutations. Novel haplotypes, including K189T + R561H (24.8%), were identified for the first time in Rwanda. The BTB/POZ domain mutation H384R was observed in 6.4% of isolates, raising questions about its potential functional role. These findings highlight complex and evolving resistance patterns and emphasize the urgent need for continued molecular surveillance and functional validation to inform malaria control strategies in Rwanda.

Malaria remains a major public health threat, particularly in sub-Saharan Africa. In Rwanda, Artemether-Lumefantrine (AL; Coartem) has been the primary treatment for uncomplicated malaria, though its efficacy is increasingly in question. Using clinical data and Plasmodium biobanks from King Faisal Hospital Kigali, we analyzed 23 selected samples from patient with recurrent malaria. Genotyping confirmed recrudescence rather than reinfection. Following the initial AL treatment, 56.5% (microscopy) and 83.3% (qPCR) remained positive, with symptoms persisting. After a second treatment, positivity declined but was still notable. Sequencing analysis revealed widespread MDR1 Y184F mutations and cumulative Pfkelch13 mutations, including H384R in the BTB/POZ domain, associated with treatment failure. Four failing strains lacked kelch13 mutations, indicating alternative resistance mechanisms. These findings support the need for expanded genetic surveillance to preserve ACT efficacy.

Malaria remains a significant public health challenge, particularly in endemic regions. The extensive genetic diversity of Plasmodium falciparum (Pf) complicates outbreak prediction and transmission control. One of its most polymorphic markers, merozoite surface protein 2 (MSP2), presents a potential target for molecular surveillance. This cross-sectional study, conducted at King Faisal Hospital Rwanda (KFHR) from October 2021 to June 2023, assessed MSP2’s utility in malaria prediction. PfMSP2 was sequenced, and selected amplicons were cloned, expressed in bacteria, and purified. These antigens were tested against sera from malaria patients and geographically diverse healthy individuals, with complementary surveys contextualizing serological findings. Of the 75 processed monoallelic clinical isolates, 3D7 strains predominated over FC27. Three MSP2-derived biomarkers were produced, eliciting significantly low IgG responses in malaria patients and Belgian controls, but a complex pattern emerged in healthy individuals, with significant differences between Rwandan and Cameroonian samples. IgG3 was the predominant subclass in individuals with high IgG responses. Notably, Rwandan individuals with weak humoral responses to the tested antigens but also other with high responses experienced malaria episodes in the subsequent year. These findings highlight MSP2 polymorphism as a valuable tool for malaria surveillance and outbreak prediction. Integrating genotyping and serology could enable precise, community-specific malaria risk assessments, strengthening control strategies.

In Cameroon, like in other African countries, infusions of Artemisia afra and Artemisia annua are widely used for the management of health-related problems, including malaria. The secondary metabolite contents of medicinal plants vary between different geographical regions and seasons, directly influencing their effectiveness in treating ailments. This study explores the phytochemical diversity and anti-plasmodial potential of A. annua and A. afra from distinct geographical locations within Cameroon, aiming to define the optimal chemical composition in terms of anti-plasmodial activity. Extracts were prepared from plants collected from diverse regions in Cameroon during both the rainy and dry seasons, and their metabolic contents were analyzed using Thin-Layer Chromatography (TLC), High Performance Liquid Chromatography (HPLC), and Gas Chromatography (GC). Their anti-plasmodial potential was assessed on a chloroquine-sensitive 3D7 Plasmodium falciparum strain. Additionally, the environmental parameters of the collecting sites were retrieved from multispectral satellite imagery. The activity profiles of the samples were associated with their environment, with distinct phytochemical compositions observed for each sample based on its geographical origin and season. Traces of artemisinin were detected in some of the A. afra samples, but it was present in the A. annua samples at a significantly higher concentration, especially in the rainy season samples (highest concentration in the Adamawa region, at 8.9% m/m artemisinin in the dry extract). Both plants are active at different levels, with A. annua more active due to the presence of artemisinin and A. afra probably active due to the presence of polyphenols. Both season and geographical location influence both plants’ metabolic contents and hence their antimalaria activity. These findings suggest that the selection of a suitable Artemisia sample for use as a potential antimalarial treatment should take into consideration its geographical origin and the period of collection.

Malaria is the most widespread endemic disease in Cameroon, and asymptomatic Plasmodium (gametocyte) carriers (APCs) constitute more than 95% of infectious human reservoirs in malaria endemic settings. This study assesses the knowledge of asymptomatic malaria (ASM) among health care workers (HCWs) in health facilities (HFs) in the Centre Region of Cameroon and the acceptability of using Artemisia afra tea to treat APCs. A cross-sectional descriptive survey was conducted among 100 HCWs, in four randomly selected HFs in the Centre Region, in the period of 1–20 April 2022, using semi-structured self-administered questionnaires. Logistic regression analyses were performed to determine factors associated with knowledge. More than seven in eight (88%) respondents were aware of the existence of ASM, 83% defined ASM correctly, 75% knew how it was diagnosed, 70% prescribe ACTs for APCs, and 51.1% were informed about ASM transmission. The professional category of HCWs was significantly associated with their knowledge of the existence and transmission of ASM, and longevity of service was associated with knowledge of transmission (p < 0.05). Two-thirds (67%) of respondents knew about Artemisia afra tea, 53.7% believed that it was effective in treating ASM, and 79% were willing to prescribe it if authorized. There was a fair level of knowledge of ASM among HCWs in the study settings.

There are over 500 species of the genus Artemisia in the Asteraceae family distributed over the globe, with varying potentials to treat different ailments. Following the isolation of artemisinin (a potent anti-malarial compound with a sesquiterpene backbone) from Artemisia annua, the phytochemical composition of this species has been of interest over recent decades. Additionally, the number of phytochemical investigations of other species, including those of Artemisia afra in a search for new molecules with pharmacological potentials, has increased in recent years. This has led to the isolation of several compounds from both species, including a majority of monoterpenes, sesquiterpenes, and polyphenols with varying pharmacological activities. This review aims to discuss the most important compounds present in both plant species with anti-malarial properties, anti-inflammatory potentials, and immunomodulating properties, with an emphasis on their pharmacokinetics and pharmacodynamics properties. Additionally, the toxicity of both plants and their anti-malaria properties, including those of other species in the genus Artemisia, is discussed. As such, data were collected via a thorough literature search in web databases, such as ResearchGate, ScienceDirect, Google scholar, PubMed, Phytochemical and Ethnobotanical databases, up to 2022. A distinction was made between compounds involved in a direct anti-plasmodial activity and those expressing anti-inflammatory and immunomodulating activities or anti-fever properties. For pharmacokinetics activities, a distinction was made between compounds influencing bioavailability (CYP effect or P-Glycoprotein effect) and those affecting the stability of pharmacodynamic active components.