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47 ud af 47 tidsskrifter valgt, søgeord (malaria) valgt, emner højest 180 dage gamle, sorteret efter nyeste først.
355 emner vises.
Malaria Journal, 9.01.2024
Tilføjet 9.01.2024
Abstract Background Malaria continues to pose a significant health threat. Rapid identification of malaria infections and the deployment of active surveillance tools are crucial for achieving malaria elimination in regions where malaria is endemic, such as certain areas of Thailand. In this study, an anomaly detection system is introduced as an early warning mechanism for potential malaria outbreaks in countries like Thailand. Methods Unsupervised clustering-based, and time series-based anomaly detection algorithms are developed and compared to identify abnormal malaria activity in Thailand. Additionally, a user interface tailored for anomaly detection is designed, enabling the Thai malaria surveillance team to utilize these algorithms and visualize regions exhibiting unusual malaria patterns. Results Nine distinct anomaly detection algorithms we developed. Their efficacy in pinpointing verified outbreaks was assessed using malaria case data from Thailand spanning 2012 to 2022. The historical average threshold-based anomaly detection method triggered three times fewer alerts, while correctly identifying the same number of verified outbreaks when compared to the current method used in Thailand. A limitation of this analysis is the small number of verified outbreaks; further consultation with the Division of Vector Borne Disease could help identify more verified outbreaks. The developed dashboard, designed specifically for anomaly detection, allows disease surveillance professionals to easily identify and visualize unusual malaria activity at a provincial level across Thailand. Conclusion An enhanced early warning system is proposed to bolster malaria elimination efforts for countries with a similar malaria profile to Thailand. The developed anomaly detection algorithms, after thorough comparison, have been optimized for integration with the current malaria surveillance infrastructure. An anomaly detection dashboard for Thailand is built and supports early detection of abnormal malaria activity. In summary, the proposed early warning system enhances the identification process for provinces at risk of outbreaks and offers easy integration with Thailand’s established malaria surveillance framework.
Læs mere Tjek på PubMedMalaria Journal, 5.01.2024
Tilføjet 5.01.2024
Abstract Background Endothelial cells (ECs) play a major role in malaria pathogenesis, as a point of direct contact of parasitized red blood cells to the blood vessel wall. The study of cytoskeleton structures of ECs, whose main functions are to maintain shape and provide strength to the EC membrane is important in determining the severe sequelae of Plasmodium falciparum malaria. The work investigated the cytoskeletal changes (microfilaments-actin, microtubules-tubulin and intermediate filaments-vimentin) in ECs induced by malaria sera (Plasmodium vivax, uncomplicated P. falciparum and complicated P. falciparum), in relation to the levels of pro-inflammatory cytokines. Methods Morphology and fluorescence intensity of EC cytoskeleton stimulated with malaria sera were evaluated using immunofluorescence technique. Levels of tumour necrosis factor (TNF) and interferon (IFN)-gamma (γ) were determined using enzyme-linked immunosorbent assay (ELISA). Control experimental groups included ECs incubated with media alone and non-malaria patient sera. Experimental groups consisted of ECs incubated with malaria sera from P. vivax, uncomplicated P. falciparum and complicated P. falciparum. Morphological scores of cytoskeletal alterations and fluorescence intensity were compared across each experiment group, and correlated with TNF and IFN-γ. Results The four morphological changes of cytoskeleton included (1) shrinkage of cytoskeleton and ECs with cortical condensation, (2) appearance of eccentric nuclei, (3) presence of “spiking pattern” of cytoskeleton and EC membrane, and (4) fragmentation and discontinuity of cytoskeleton and ECs. Significant damages were noted in actin filaments compared to tubulin and vimentin filaments in ECs stimulated with sera from complicated P. falciparum malaria. Morphological damages to cytoskeleton was positively correlated with fluorescence intensity and the levels of TNF and IFN-γ. Conclusions ECs stimulated with sera from complicated P. falciparum malaria showed cytoskeletal alterations and increased in fluorescence intensity, which was associated with high levels of TNF and IFN-γ. Cytoskeletal changes of ECs incubated with complicated P. falciparum malaria sera can lead to EC junctional alteration and permeability changes, which is mediated through apoptotic pathway. The findings can serve as a basis to explore measures to strengthen EC cytoskeleton and alleviate severe malaria complications such as pulmonary oedema and cerebral malaria. In addition, immunofluorescence intensity of cytoskeleton could be investigated as potential prognostic indicator for malaria severity.
Læs mere Tjek på PubMedMalaria Journal, 5.01.2024
Tilføjet 5.01.2024
Abstract Background Decreased efficacy of artemisinin-based combination therapy (ACT) for Plasmodium falciparum malaria has been previously reported in patients with sickle cell disease (SCD). The main purpose of this study was to investigate the in vitro susceptibility of isolates to dihydro-artemisinin (DHA) to provide a hypothesis to explain this treatment failure. Methods Isolates were collected from patients attending health centres in Abidjan with uncomplicated P. falciparum malaria. The haemoglobin type has been identified and in vitro drug sensitivity tests were conducted with the ring stage assay and maturation inhibition assay. Results 134 isolates were obtained. Parasitaemia and haemoglobin levels at inclusion were lower in patients with haemoglobin HbSS and HbSC than in patients with normal HbAA. After ex vivo RSA and drug inhibition assays, the lowest rate of parasitic growth was found with isolates from HbAS red cells. Conversely, a significantly higher survival rate of parasites ranging from 15 to 34% were observed in isolates from HbSS. Isolates with in vitro reduced DHA sensitivity correlate with lower RBC count and haematocrit and higher parasitaemia at inclusion compared to those with isolates with normal DHA sensitivity. However, this decrease of in vitro sensitivity to DHA was not associated with Kelch 13-Propeller gene polymorphism. Conclusion This study highlights an in vitro decreased sensitivity to DHA, for isolates collected from HbSS patients, not related to the Pfkelch13 gene mutations. These results are in line with recent studies pointing out the role of the redox context in the efficacy of the drug. Indeed, SCD red cells harbour a highly different ionic and redox context in comparison with normal red cells. This study offers new insights into the understanding of artemisinin selective pressure on the malaria parasite in the context of haemoglobinopathies in Africa.
Læs mere Tjek på PubMedMalaria Journal, 5.01.2024
Tilføjet 5.01.2024
Abstract Background In Spain, the risk of imported malaria has increased in recent years due to the rise in international travel and migration. Little is known about the knowledge, information sources, clinical practice, and specific needs of primary care physicians (PCPs) concerning malaria despite the pivotal role played by these professionals in managing the health of tourists. The objective of this study was to assess the knowledge, attitudes, and practices of PCPs in Spain regarding malaria. Methods This research analyses data from (1) a cross-sectional nationwide survey assessing the knowledge and attitudes of PCPs regarding malaria, and (2) a retrospective review of 373 malaria cases appearing in primary care medical records (PCMRs) in the Madrid area over the past 15 years to determine how cases were documented, managed, or characterized in the primary care setting. Results The survey findings reveal a modest level of self-perceived familiarity with malaria (221/360, 57.6%), even though 32.8% of the practitioners reported having delivered care for confirmed or suspected cases of the disease, these practitioners had greater knowledge of malaria (80.4%) compared to physicians who reported not having delivered care for malaria (19.6%, p
Læs mere Tjek på PubMedMalaria Journal, 5.01.2024
Tilføjet 5.01.2024
Abstract Africa and the United States are both large, heterogeneous geographies with a diverse range of ecologies, climates and mosquito species diversity which contribute to disease transmission and nuisance biting. In the United States, mosquito control is nationally, and regionally coordinated and in so much as the Centers for Disease Control (CDC) provides guidance, the Environmental Protection Agency (EPA) provides pesticide registration, and the states provide legal authority and oversight, the implementation is usually decentralized to the state, county, or city level. Mosquito control operations are organized, in most instances, into fully independent mosquito abatement districts, public works departments, local health departments. In some cases, municipalities engage independent private contractors to undertake mosquito control within their jurisdictions. In sub–Saharan Africa (SSA), where most vector-borne disease endemic countries lie, mosquito control is organized centrally at the national level. In this model, the disease control programmes (national malaria control programmes or national malaria elimination programmes (NMCP/NMEP)) are embedded within the central governments’ ministries of health (MoHs) and drive vector control policy development and implementation. Because of the high disease burden and limited resources, the primary endpoint of mosquito control in these settings is reduction of mosquito borne diseases, primarily, malaria. In the United States, however, the endpoint is mosquito control, therefore, significant (or even greater) emphasis is laid on nuisance mosquitoes as much as disease vectors. The authors detail experiences and learnings gathered by the delegation of African vector control professionals that participated in a formal exchange programme initiated by the Pan-African Mosquito Control Association (PAMCA), the University of Notre Dame, and members of the American Mosquito Control Association (AMCA), in the United States between the year 2021 and 2022. The authors highlight the key components of mosquito control operations in the United States and compare them to mosquito control programmes in SSA countries endemic for vector-borne diseases, deriving important lessons that could be useful for vector control in SSA.
Læs mere Tjek på PubMedMalaria Journal, 5.01.2024
Tilføjet 5.01.2024
Abstract Background Approximately 32 million pregnant women are at risk of malaria with up to 10,000 maternal deaths and 200,000 neonates at risk annually. Intermittent Preventive Treatment (IPT) with sulfadoxine-pyrimethamine (SP) is recommended by the World Health Organization (WHO) to reduce disease in pregnancy and adverse maternal and newborn outcomes. At least three doses of SP should be taken by pregnant women during antenatal consultation (ANC) beginning from the thirteenth week of pregnancy till parturition. The aim of this study was to assess uptake of IPT during pregnancy and risk factors for maternal anaemia and infant birth weight in Dschang, West region of Cameroon. Methods A total of 380 consenting pregnant women at delivery were recruited in a cross- sectional prospective survey between January to December 2021. Data on ANC attendance, total dose of IPT and history of malaria were abstracted from hospital ANC records while socio-demographic characteristics, bed net use and obstetrics history of each participant were also recorded through an interview. Further, blood samples were collected from the intervillous space for assessment of maternal anaemia and microscopic parasitology. Nested PCR based on amplification of the Plasmodium 18S sRNA was carried out to detect submicroscopic infection. IPTp coverage was calculated per WHO recommendation and the prevalence of anaemia and low birth weight were estimated as proportions in the total sample of pregnant women and live births, respectively. Crude and adjusted odds ratios and their 95% confidence intervals were used to estimate associations between pregnancy outcomes considered and risk factors in specific and general models. A p
Læs mere Tjek på PubMedEmmanuel Bottieau, Moustapha Mbow, Isabel Brosius, Clémentine Roucher, Cheikh Tidiane Gueye, Ousmane Thiam Mbodj, Babacar Thiendella Faye, Annelies De Hondt, Bart Smekens, Diana Arango, Christophe Burm, Achilleas Tsoumanis, Linda Paredis, Yven Van Herrewege, Idzi Potters, Joachim Richter, Anna Rosanas-Urgell, Badara Cissé, Souleymane Mboup, Katja Polman
Nature, 4.01.2024
Tilføjet 4.01.2024
Clinical Infectious Diseases, 4.01.2024
Tilføjet 4.01.2024
Abstract The field of infectious diseases saw numerous exciting advances in 2023. Trials of new antibiotics and treatment regimens sought to address rising rates of antimicrobial resistance. Other studies focused on the most appropriate use of currently available treatments, balancing the dual goals of providing effective treatment and impactful antimicrobial stewardship. Improvements in disease prevention were made through trials of both new vaccines and new chemoprophylaxis approaches. Concerning trends this year included increasing rates of invasive group A streptococcal infections, medical tourism associated cases of fungal meningitis, and the return of locally acquired malaria to the United States. This review covers some of these notable trials and clinical developments in infectious diseases in the past year.
Læs mere Tjek på PubMedJournal of Infectious Diseases, 4.01.2024
Tilføjet 4.01.2024
Abstract Human babesiosis is a potentially fatal tick-borne disease caused by intraerythrocytic Babesia parasites. The emergence of resistance to recommended therapies highlights the need for new and more effective treatments. Here we demonstrate that the 8-aminoquinoline antimalarial drug tafenoquine inhibits the growth of different Babesia species in vitro, is highly effective against Babesia microti and Babesia duncani in mice and protects animals from lethal infection caused by atovaquone-sensitive and -resistant B. duncani strains. We further show that a combination of tafenoquine and atovaquone achieves cure with no recrudescence in both models of human babesiosis. Interestingly, elimination of B. duncani infection in animals following drug treatment also confers immunity to subsequent challenge. Altogether, the data demonstrate superior efficacy of tafenoquine plus atovaquone combination over current therapies for the treatment of human babesiosis and highlight its potential in providing protective immunity against Babesia following parasite clearance.
Læs mere Tjek på PubMedAmerican Journal of Tropical Medicine and Hygiene, 3.01.2024
Tilføjet 3.01.2024
Journal Name: The American Journal of Tropical Medicine and Hygiene Volume: 110 Issue: 1 Pages: 20-31
Læs mere Tjek på PubMedAmerican Journal of Tropical Medicine and Hygiene, 3.01.2024
Tilføjet 3.01.2024
Journal Name: The American Journal of Tropical Medicine and Hygiene Volume: 110 Issue: 1 Pages: 64-68
Læs mere Tjek på PubMedAmerican Journal of Tropical Medicine and Hygiene, 3.01.2024
Tilføjet 3.01.2024
Journal Name: The American Journal of Tropical Medicine and Hygiene Volume: 110 Issue: 1 Pages: 69-78
Læs mere Tjek på PubMedAmerican Journal of Tropical Medicine and Hygiene, 3.01.2024
Tilføjet 3.01.2024
Journal Name: The American Journal of Tropical Medicine and Hygiene Volume: 110 Issue: 1 Pages: 79-82
Læs mere Tjek på PubMedAmerican Journal of Tropical Medicine and Hygiene, 3.01.2024
Tilføjet 3.01.2024
Journal Name: The American Journal of Tropical Medicine and Hygiene Volume: 110 Issue: 1 Pages: 127-132
Læs mere Tjek på PubMedBMC Infectious Diseases, 3.01.2024
Tilføjet 3.01.2024
Abstract Background Imported cerebral malaria (CM) cases in non-endemic areas are often misdiagnosed, which delays treatment. Post-malaria neurological syndrome (PMNS) after recovery from severe malaria can also complicate diagnosis. Case We report an imported malaria case from West Africa with two sequential episodes with neurological syndromes within about a month. The first episode was diagnosed as CM with microscopy-positive Plasmodium falciparum infection. The second episode, occurring a month after the recovery from the first CM episode, was consistent with PMNS, since malaria parasites were not detected by microscopy in peripheral blood smears. However, this diagnosis was complicated by the detection of Plasmodium vivax in peripheral blood by PCR, suggesting a potential cause of the second episode by P. vivax. Conclusion This study suggests that PMNS often occurs after severe falciparum malaria. Concurrent P. vivax infection with pathogenic biomass being predominantly extravascular further complicates accurate diagnosis.
Læs mere Tjek på PubMedKatherine L. Williams, Steve Guerrero, Yevel Flores-Garcia, Dongkyoon Kim, Kevin S. Williamson, Christine Siska, Pauline Smidt, Sofia Z. Jepson, Kan Li, S. Moses Dennison, Shamika Mathis-Torres, Xiaomu Chen, Ulrike Wille-Reece, Randall S. MacGill, Michael Walker, Erik Jongert, C. Richter King, Christian Ockenhouse, Jacob Glanville, James E. Moon, Jason A. Regules, Yann Chong Tan, Guy Cavet, Shaun M. Lippow, William H. Robinson, Sheetij Dutta, Georgia D. Tomaras, Fidel Zavala, Randal R. Ketchem, Daniel E. Emerling
Nature, 2.01.2024
Tilføjet 2.01.2024
Malaria Journal, 2.01.2024
Tilføjet 2.01.2024
Abstract Background Patients’ adherence to artemisinin-based combination therapy (ACT) is a malaria control strategy. Studies report varied experiences regarding patients’ adherence to ACT. The study aimed at determining factors influencing patients’ adherence to ACT for malaria in Kamuli, Uganda. Methods In a longitudinal study, 1266 participants at 8 public health facilities were enrolled. Equal numbers (422) were assigned to the three arms (no follow-up, day 2 and day 4). To establish the mean difference between groups, Student t-test was used and a chi-square test was used for proportionality. A multivariate logistic regression analysis was used to establish the influence of predictor variables on the dependent variable. Statistical significance was established at p
Læs mere Tjek på PubMedMalaria Journal, 2.01.2024
Tilføjet 2.01.2024
Abstract Background Differences between urban and rural contexts in terms of sociodemographic characteristics, geographical features and risk perceptions may lead to disparities in coverage and related outcomes of community-based preventive interventions, such as seasonal malaria chemoprevention (SMC). This study investigated urban–rural differences in SMC coverage and other programme outcomes, as well as child and caregiver characteristics of target populations in nine implementing states in Nigeria during the 2022 SMC round. Methods This is a comparative cross-sectional study based on comprehensive end-of-round household surveys conducted in nine states where SMC was delivered in Nigeria in 2022. Data of 11,880 caregiver-child pairs were included in the analysis. Rural-urban differences in SMC outcomes and child and caregiver characteristics were assessed, first by using Pearsons’ chi-square test for independence for categorical variables. Univariate multilevel mixed-effect logistic regression models, with random intercepts for cluster units, were used to quantify the strength of association between location and each SMC coverage and related outcomes. Results Significant urban-rural differences were observed in caregivers’ sociodemographic characteristics, such as age, gender, level of education, occupation status and health-seeking behaviour for febrile childhood illnesses. Disparities were also seen in terms of SMC coverage and related outcomes, with lower odds of the receipt of Day 1 dose direct observation of the administration of Day 1 dose by community distributors, receipt of the full three-day course of SMC medicines and receipt of SMC in all cycles of the annual round among children residing in urban areas, compared with those residing in rural areas. Similarly, urban-dwelling caregivers had lower odds of being knowledgeable of SMC and believing in the protective effect of SMC than rural-dwelling caregivers. Conclusion Findings highlight observable urban-rural disparities in SMC programme delivery and related outcomes, as well as target population characteristics, underscoring the need for context-specific strategies to ensure optimal delivery of SMC and improve programme implementation outcomes in urban settings.
Læs mere Tjek på PubMedMalaria Journal, 2.01.2024
Tilføjet 2.01.2024
Abstract Background Progress toward malaria elimination is increasing as many countries near zero indigenous malaria cases. In settings nearing elimination, interventions will be most effective at interrupting transmission when targeted at the residual foci of transmission. These foci may be missed due to asymptomatic infections. To solve this problem, the World Health Organization recommends reactive case detection (RACD). This case study was conducted to identify individuals with asymptomatic malaria, their predisposing risk factors and recommend RACD in Asutsuare, Ghana based on literature review and a cross sectional study. Methods The study involved a search on PubMed and Google Scholar of literature published between 1st January, 2009–14th August, 2023 using the search terms “malaria” in “Asutsuare”. Furthermore, structured questionnaires were administered to one hundred individuals without symptoms of malaria and screened using rapid diagnostic test (RDT) kits, microscopy and real-time polymerase chain reaction (rt-PCR). Malaria prevalence based on the three diagnostic techniques as well as potential malaria risk factors were assessed through questionnaires in a cross-sectional study. Results Cumulatively, sixty-four (64) studies (Google Scholar, 57 and PubMed, 7) were reviewed and 22 studies included in the literature on malaria in Asutsuare, Ghana. Significant risk factors were occupation, distance from a house to a waterbody, age group and educational level. Out of the 100 samples, 3 (3%) were positive by RDT, 6 (6%) by microscopy and 9 (9%) by rt-PCR. Ages 5–14.9 years had the highest mean malaria parasite densities of 560 parasites/µl with Plasmodium falciparum as the dominant species in 4 participants. Moreover, in the age group ≥ 15, 2 participants (1 each) harboured P. falciparum and Plasmodium malariae parasites. RDT had a higher sensitivity (76.54%; CI95 66.82–85.54) than rt-PCR (33.33%; CI95 4.33–77.72), while both rt-PCR and RDT were observed to have a higher specificity (92.55; CI95 85.26–96.95) and (97.30; CI95 93.87–99.13), respectively in the diagnosis of malaria. Conclusion In Asutsuare, Ghana, a low endemic area, the elimination of malaria may require finding individuals with asymptomatic infections. Given the low prevalence of asymptomatic individuals identified in this study and as repleted in the literature review, which favours RACD, Asutsuare is a possible setting receptive for RACD implementation.
Læs mere Tjek på PubMedMalaria Journal, 2.01.2024
Tilføjet 2.01.2024
Abstract In Southeast Asia malaria elimination is targeted by 2030. Cambodia aims to achieve this by 2025, driven in large part by the urgent need to control the spread of artemisinin-resistant falciparum malaria infections. Rapid elimination depends on sustaining early access to diagnosis and effective treatment. In much of Cambodia, rapid elimination will rely on a village malaria worker (VMW) network. Yet as malaria declines and is no longer a common cause of febrile illness, VMWs may become less popular with febrile patients, as VMWs do not diagnose or treat other conditions at present. There is a risk that VMWs become inactive and malaria rebounds before the complete interruption of transmission is achieved. During 2021–23 a large-scale operational research study was conducted in western Cambodia to explore how a VMW network could be sustained by including health activities that cover non-malarial illnesses to encourage febrile patients to continue to attend. 105 VMWs received new rapid diagnostic tests (including dengue antigen–antibody and combined malaria/C-reactive protein tests), were trained in electronic data collection, and attended health education packages on hygiene and sanitation, disease surveillance and first aid, management of mild illness, and vaccination and antenatal care. In August 2023 the National Malaria Control Programme of Cambodia convened a stakeholder meeting in Battambang, Cambodia. Findings from the study were reviewed in the context of current malaria elimination strategies. The discussions informed policy options to sustain the relevance of the VMW network in Cambodia, and the potential for its integration with other health worker networks. This expansion could ensure VMWs remain active and relevant until malaria elimination is accomplished.
Læs mere Tjek på PubMedMalaria Journal, 2.01.2024
Tilføjet 2.01.2024
Abstract Background Rapid diagnostic tests (RDTs) that detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2) are exclusively deployed in Uganda, but deletion of the pfhrp2/3 target gene threatens their usefulness as malaria diagnosis and surveillance tools. Methods A cross-sectional survey was conducted at 40 sites across four regions of Uganda in Acholi, Lango, W. Nile and Karamoja from March 2021 to June 2023. Symptomatic malaria suspected patients were recruited and screened with both HRP2 and pan lactate dehydrogenase (pLDH) detecting RDTs. Dried blood spots (DBS) were collected from all patients and a random subset were used for genomic analysis to confirm parasite species and pfhrp2 and pfhrp3 gene status. Plasmodium species was determined using a conventional multiplex PCR while pfhrp2 and pfhrp3 gene deletions were determined using a real-time multiplex qPCR. Expression of the HRP2 protein antigen in a subset of samples was further assessed using a ELISA. Results Out of 2435 symptomatic patients tested for malaria, 1504 (61.8%) were positive on pLDH RDT. Overall, qPCR confirmed single pfhrp2 gene deletion in 1 out of 416 (0.2%) randomly selected samples that were confirmed of P. falciparum mono-infections. Conclusion These findings show limited threat of pfhrp2/3 gene deletions in the survey areas suggesting that HRP2 RDTs are still useful diagnostic tools for surveillance and diagnosis of P. falciparum malaria infections in symptomatic patients in this setting. Periodic genomic surveillance is warranted to monitor the frequency and trend of gene deletions and its effect on RDTs.
Læs mere Tjek på PubMedJan Šlapeta, Colin J. Sutherland, Hans-Peter Fuehrer
Trends in Parasitology, 30.12.2023
Tilføjet 30.12.2023
We have read with great interest the opinion by Snounou et al. [1] with regard to ‘Plasmodium ovalecurtisi’ and ‘Plasmodium ovalewallikeri’ for what represents two cryptic species within Plasmodium ovale Stephens, 1922. These authors are correct to highlight the inadequacy of current nomenclature for these malaria parasites. However, it is essential to note that both names, as proposed [1], represent nomina nuda, constituting an error within the framework of zoological nomenclature.
Læs mere Tjek på PubMedFarah Ishtiaq
Trends in Parasitology, 30.12.2023
Tilføjet 30.12.2023
Diamond et al. recently identified malaria and dengue as high-priority diseases in wastewater surveillance for climate-change-driven shifts in pathogen dynamics. When employing wastewater surveillance for vector-borne pathogens it is essential to take into account the geographical context, pathogen biology, and the availability of sewage networks for meaningful interventions.
Læs mere Tjek på PubMedNew England Journal of Medicine, 28.12.2023
Tilføjet 28.12.2023
New England Journal of Medicine, Volume 389, Issue 26, Page 2497-2498, December 2023.
Læs mere Tjek på PubMedGuofa Zhou, Daibin Zhong, Delenasaw Yewhalaw, Guiyun Yan
Trends in Parasitology, 23.12.2023
Tilføjet 23.12.2023
The encroachment and rapid spread of Anopheles stephensi across Africa presents a significant challenge to malaria control and elimination efforts. Understanding the ecology and behavior of An. stephensi will critically inform control measures and provide prerequisite knowledge for exploring new larval and adult control tools to contain its spread.
Læs mere Tjek på PubMedMalaria Journal, 22.12.2023
Tilføjet 22.12.2023
Abstract Background Gene drive modified mosquitoes (GDMMs) have the potential to address Africa’s persistent malaria problem, but are still in early stages of development and testing. Continuous engagement of African stakeholders is crucial for successful evaluation and implementation of these technologies. The aim of this multi-country study was, therefore, to explore the insights and recommendations of key stakeholders across Africa on the potential of GDMMs for malaria control and elimination in the continent. Methods A concurrent mixed-methods study design was used, involving a structured survey administered to 180 stakeholders in 25 countries in sub-Saharan Africa, followed by 18 in-depth discussions with selected groups and individuals. Stakeholders were drawn from academia, research and regulatory institutions, government ministries of health and environment, media and advocacy groups. Thematic content analysis was used to identify key topics from the in-depth discussions, and descriptive analysis was done to summarize information from the survey data. Results Despite high levels of awareness of GDMMs among the stakeholders (76.7%), there was a relatively low-level of understanding of their key attributes and potential for malaria control (28.3%). When more information about GDMMs was provided to the stakeholders, they readily discussed their insights and concerns, and offered several recommendations to ensure successful research and implementation of the technology. These included: (i) increasing relevant technical expertise within Africa, (ii) generating local evidence on safety, applicability, and effectiveness of GDMMs, and (iii) developing country-specific regulations for safe and effective governance of GDMMs. A majority of the respondents (92.9%) stated that they would support field trials or implementation of GDMMs in their respective countries. This study also identified significant misconceptions regarding the phase of GDMM testing in Africa, as several participants incorrectly asserted that GDMMs were already present in Africa, either within laboratories or released into the field. Conclusion Incorporating views and recommendations of African stakeholders in the ongoing research and development of GDMMs is crucial for instilling stakeholder confidence on their potential application. These findings will enable improved planning for GDMMs in Africa as well as improved target product profiles for the technologies to maximize their potential for solving Africa’s enduring malaria challenge.
Læs mere Tjek på PubMedMalaria Journal, 22.12.2023
Tilføjet 22.12.2023
Abstract The primary reason for the failure of malaria vector control across endemic regions is the widespread insecticide resistance observed in Anopheles vectors. The most dominant African vectors of malaria parasites are Anopheles gambiae and Anopheles funestus mosquitoes. These species often exhibit divergent behaviours and adaptive changes underscoring the importance of deploying active and effective measures in their control. Unlike An. gambiae, An. funestus mosquitoes are poorly studied in Benin Republic. However, recent reports indicated that An. funestus can adapt and colonize various ecological niches owing to its resistance against insecticides and adaptation to changing breeding habitats. Unfortunately, scientific investigations on the contribution of An. funestus to malaria transmission, their susceptibility to insecticide and resistance mechanism developed are currently insufficient for the design of better control strategies. In an attempt to gather valuable information on An. funestus, the present review examines the progress made on this malaria vector species in Benin Republic and highlights future research perspectives on insecticide resistance profiles and related mechanisms, as well as new potential control strategies against An. funestus. Literature analysis revealed that An. funestus is distributed all over the country, although present in low density compared to other dominant malaria vectors. Interestingly, An. funestus is being found in abundance during the dry seasons, suggesting an adaptation to desiccation. Among the An. funestus group, only An. funestus sensu stricto (s.s.) and Anopheles leesoni were found in the country with An. funestus s.s. being the most abundant species. Furthermore, An. funestus s.s. is the only one species in the group contributing to malaria transmission and have adapted biting times that allow them to bite at dawn. In addition, across the country, An. funestus were found resistant to pyrethroid insecticides used for bed nets impregnation and also resistant to bendiocarb which is currently being introduced in indoor residual spraying formulation in malaria endemic regions. All these findings highlight the challenges faced in controlling this malaria vector. Therefore, advancing the knowledge of vectorial competence of An. funestus, understanding the dynamics of insecticide resistance in this malaria vector, and exploring alternative vector control measures, are critical for sustainable malaria control efforts in Benin Republic.
Læs mere Tjek på PubMedKanako Komaki-Yasuda, Shigeyuki Kano
PLoS One Infectious Diseases, 22.12.2023
Tilføjet 22.12.2023
by Kanako Komaki-Yasuda, Shigeyuki Kano To date, only a small number of regulatory transcription factors have been predicted from the genome of Plasmodium and Apicomplexan parasites. We previously identified a nuclear factor named Prx regulatory element-binding protein (PREBP) from Plasmodium falciparum. PREBP had been suggested to bind to the cis-element in the promoter of an antioxidant pf1-cys-prx gene, thereby promoting the expression of downstream genes. PREBP has 4 putative K homology (KH) domains, which are known to bind RNA and single-stranded DNA. In this study, to understand the detailed action of PREBP in parasite cells, we first observed that in living parasite cells, PREBP was localized in the nucleus in the trophozoite and schizont stages, in which the expression of the target pf1-cys-prx was enhanced. The interaction of PREBP and the cis-element of pf1-cys-prx in the parasite cells was also confirmed. Further, the activities of PREBP deletion mutants were analyzed, and regions with repeated KH domains in PREBP seemed to be responsible for the recognition of the cis-element. These results led us to hypothesize that Plasmodium and other Apicomplexan parasites might have a transcription factor family with KH domains. Bioinformatic analysis revealed a putative ortholog group including PREBP and several Plasmodium and Apicomplexan factors with KH domains. One of the P. falciparum-derived factors, which were included in the putative ortholog group, was found to be localized at the nucleus in the trophozoite stage, indicating that it might be a novel transcription factor. The discovery of PREBP and putative transcription factors with KH domains suggested that multi-functional proteins with KH domains possibly evolved in the Apicomplexan organisms. They might play key roles in transcriptional regulatory processes that are essential for living organisms and may even represent unique drug targets for malaria therapy.
Læs mere Tjek på PubMedRichard Culleton, Geoffrey Ian McFadden
Trends in Parasitology, 21.12.2023
Tilføjet 21.12.2023
The term ‘simian malaria parasites’ has crept into the modern malaria literature as a synonym for ‘non-human primate malaria parasites’, most commonly referring to species of Plasmodium infective to Old World monkeys. As humans are also simians, we contend that this usage is erroneous, and should not be used.
Læs mere Tjek på PubMedShazia Ruybal-Pesántez, Kirsty McCann, Jessy Vibin, Sasha Siegel, Sarah Auburn, Alyssa E. Barry
Trends in Parasitology, 21.12.2023
Tilføjet 21.12.2023
Over recent years, progress in molecular markers for genotyping malaria parasites has enabled informative studies of epidemiology and transmission dynamics. Results have highlighted the value of these tools for surveillance to support malaria control and elimination strategies. There are many different types and panels of markers available for malaria parasite genotyping, and for end users, the nuances of these markers with respect to ‘use case’, resolution, and accuracy, are not well defined. This review clarifies issues surrounding different molecular markers and their application to malaria control and elimination. We describe available marker panels, use cases, implications for different transmission settings, limitations, access, cost, and data accuracy. The information provided can be used as a guide for molecular epidemiology and surveillance of malaria.
Læs mere Tjek på PubMedAnayochukwu E. Anyasodor, Kedir Y. Ahmed, Uchechukwu L. Osuagwu, Nnamdi C. Mgbemena, Bernd H. Kalinna, Subash Thapa, Shakeel Mahmood, Allen G. Ross
PLoS One Infectious Diseases, 21.12.2023
Tilføjet 21.12.2023
by Anayochukwu E. Anyasodor, Kedir Y. Ahmed, Uchechukwu L. Osuagwu, Nnamdi C. Mgbemena, Bernd H. Kalinna, Subash Thapa, Shakeel Mahmood, Allen G. Ross Background In countries with high child mortality rates, such as Nigeria, early intervention for common childhood illnesses (e.g., pneumonia and malaria) is essential for improving clinical outcomes. The timely reporting and treatment of fever is therefore critical in making a differential diagnosis and choosing an appropriate course of treatment. The present study aimed to investigate the prevalence and major risk factors associated with delays in seeking treatment for fever in children under five years of age in Nigeria. Methods This study used a total weighted sample of 7,466 children under five years of age from the 2018 National Nigerian Demographic and Health Survey. Multivariable binary logistic regression modelling was used to investigate the association between predisposing, enabling, need, health service and community level factors, and delay in treatment-seeking for fever. Results We report the delays in seeking treatment for childhood fever that was reported by mothers in the last two weeks prior to the national survey. The prevalence for delayed treatment was 62.1% (95% confidence interval [CI]: 60.1%, 64.1%). Our findings showed that there were fewer delays in seeking treatment in children aged 24–59 months (adjusted odds ratio [aOR] = 0.79, 95% CI: 0.68, 0.93), among mothers who were formally employed (aOR = 0.84; 95% CI: 0.73, 0.96), regularly attended antenatal services (aOR = 0.76, 95%CI: 0.66, 0.88), and for those who resided in wealthier households (aOR = 0.71; 95% CI: 0.56, 0.89). Children whose mothers resided in the North-West geopolitical zone of Nigeria were less likely to delay seeking treatment for fever (aOR = 0.55; 95% CI: 0.42, 0.73). However, mothers who had an unwanted pregnancy had a higher odds of delaying treatment for childhood fever (aOR = 1.58; 95% CI: 1.05, 2.39). Conclusion There were significant delays in seeking treatment for childhood fever in poorer homes found in geopolitically unstable zones of Nigeria. Mothers who were poor, unemployed, and with younger children (
Læs mere Tjek på PubMedLE Hermans, CM Centner, CM Morel, O Mbamalu, C Bonaconsa, C Ferreyra, O Lindahl, M Mendelson
International Journal of Infectious Diseases, 21.12.2023
Tilføjet 21.12.2023
Communicable diseases are the foremost cause of morbidity and mortality in sub-Saharan Africa (SSA).[1] This trend is mainly driven by the pandemics of HIV, tuberculosis, malaria, and COVID-19, neglected tropical diseases, and pneumonia and diarrhoeal disease in children.[2–4] The rising incidence of antimicrobial resistant (AMR) bacterial infections threatens to compound this already significant burden. A recent survey estimated that in 2019, the four global regions most heavily affected by AMR were all in SSA.[5]
Læs mere Tjek på PubMedCriselda Dillague, Myles H. Akabas
PLoS One Infectious Diseases, 19.12.2023
Tilføjet 19.12.2023
by Criselda Dillague, Myles H. Akabas Malaria remains a major public health threat for billions of people worldwide. Infection with obligate intracellular, unicellular parasites from the genus Plasmodium causes malaria. Plasmodium falciparum causes the deadliest form of human malaria. Plasmodium parasites are purine auxotrophic. They rely on purine import from the host red blood cell cytoplasm via equilibrative nucleoside transporters to supply substrates to the purine salvage pathway. We previously developed a high throughput screening assay to identify inhibitors of the P. falciparum Equilibrative Nucleoside Transporter Type 1 (PfENT1). Screening a small molecule library identified PfENT1 inhibitors that blocked proliferation of P. falciparum parasites in in vitro culture. The goal of the current work was to validate a high-resolution model of PfENT1 predicted by the AlphaFold protein structure prediction program. We superimposed the predicted PfENT1 structure on the human homologue structure, hENT1, and developed a structure-based sequence alignment. We mutated the residues in PfENT1 aligned with and flanking the residues in hENT1 that interact with the purine analog, nitrobenzylthioinosine (NBMPR). Mutation of the PfENT1 residues Q135, D287, and R291 that are predicted to form hydrogen bonds to purine nucleosides eliminated purine and pyrimidine transport function in various yeast-based growth and radiolabeled substrate uptake assays. Mutation of two flanking residues, W53 and S290, also resulted in inactive protein. Mutation of L50 that forms hydrophobic interactions with the purine nucleobase reduced transport function. Based on our results the AlphaFold predicted structure for PfENT1 may be useful in guiding medicinal chemistry efforts to improve the potency of our PfENT1 inhibitors.
Læs mere Tjek på PubMedMalaria Journal, 19.12.2023
Tilføjet 19.12.2023
Abstract Background Early phase malaria vaccine field trials typically measure malaria infection by PCR or thick blood smear microscopy performed on serially sampled blood. Vaccine efficacy (VE) is the proportion reduction in an endpoint due to vaccination and is often calculated as VEHR = 1–hazard ratio or VERR = 1–risk ratio. Genotyping information can distinguish different clones and distinguish multiple infections over time, potentially increasing statistical power. This paper investigates two alternative VE endpoints incorporating genotyping information: VEmolFOI, the vaccine-induced proportion reduction in incidence of new clones acquired over time, and VEC, the vaccine-induced proportion reduction in mean number of infecting clones per exposure. Methods Power of VEmolFOI and VEC was compared to that of VEHR and VERR by simulations and analytic derivations, and the four VE methods were applied to three data sets: a Phase 3 trial of RTS,S malaria vaccine in 6912 African infants, a Phase 2 trial of PfSPZ Vaccine in 80 Burkina Faso adults, and a trial comparing Plasmodium vivax incidence in 466 Papua New Guinean children after receiving chloroquine + artemether lumefantrine with or without primaquine (as these VE methods can also quantify effects of other prevention measures). By destroying hibernating liver-stage P. vivax, primaquine reduces subsequent reactivations after treatment completion. Results In the trial of RTS,S vaccine, a significantly reduced number of clones at first infection was observed, but this was not the case in trials of PfSPZ Vaccine or primaquine, although the PfSPZ trial lacked power to show a reduction. Resampling smaller data sets from the large RTS,S trial to simulate phase 2 trials showed modest power gains from VEC compared to VEHR for data like those from RTS,S, but VEC is less powerful than VEHR for trials in which the number of clones at first infection is not reduced. VEmolFOI was most powerful in model-based simulations, but only the primaquine trial collected enough serial samples to precisely estimate VEmolFOI. The primaquine VEmolFOI estimate decreased after most control arm liver-stage infections reactivated (which mathematically resembles a waning vaccine), preventing VEmolFOI from improving power. Conclusions The power gain from the genotyping methods depends on the context. Because input parameters for early phase power calculations are often uncertain, these estimators are not recommended as primary endpoints for small trials unless supported by targeted data analysis. Trial registrations: NCT00866619, NCT02663700, NCT02143934.
Læs mere Tjek på PubMedMalaria Journal, 18.12.2023
Tilføjet 18.12.2023
Abstract Background Pyrethroids are the main insecticides used in vector control for malaria. However, their extensive use in the impregnation of long-lasting insecticidal nets (LLINs) and indoor residual spraying has led to the development of resistance, threatening its success as a tool for malaria control. Baseline data prior to large scale distribution of LLINs are important for the implementation of efficient strategies. However, no data on the susceptibility of malaria vectors is available in the Moyen-Ogooué Province in Gabon. The aim of this study was to assess the susceptibility to pyrethroids and organochlorides of malaria vectors from a semi-urban and rural areas of the province and to determine the frequency of insecticide resistance genes. Methods Larvae were collected from breeding sites in Lambaréné and Zilé and reared to adults. Three to five-day old female Anopheles gambiae sensu lato mosquitoes were used in cone tube assays following the WHO susceptibility tests protocol for adult mosquitoes. A subsample was molecularly identified using the SINE200 protocol and the frequency of Vgsc-1014 F and − 1014 S mutations were determined. Results Anopheles gambiae sensu stricto (s.s.) was the sole species present in both Lambaréné and Zilé. Mosquito populations from the two areas were resistant to pyrethroids and organochlorides. Resistance was more pronounced for permethrin and DDT with mortality lower than 7% for both insecticides in the two study areas. Mosquitoes were statistically more resistant (P
Læs mere Tjek på PubMedOumar Attaher, Bruce Swihart, Lauren Dang, Gaoussou Santara, Almahamoudou Mahamar, Sekouba Keita, Adama Dembele, Bacary Soumana Diarra, Djibrilla Issiaka, Amadou Barry, Youssoufa Sidibé, Yahia T. Dicko, Seydou Traore, Fanta Koita, Ouelematou Ndiaye, Alassane Dicko, Jonathan D. Kurtis, Patrick E. Duffy, Michal Fried
International Journal of Infectious Diseases, 17.12.2023
Tilføjet 17.12.2023
Infection with Plasmodium falciparum is a major public health problem. Clinical presentation varies from asymptomatic infection to severe disease. In areas of high malaria transmission, young children bear most of the burden of severe disease and mortality [1].
Læs mere Tjek på PubMedMalaria Journal, 17.12.2023
Tilføjet 17.12.2023
Abstract Background Malaria is still endemic in South Korea. However, limited information is available on the current Anopheles breeding sites and the occurrence of insecticide resistance-associated genetic mutations and their distribution needed to control the malaria vector efficiently. Methods This study explored breeding sites of Anopheline adults in Gimpo-si, near the demilitarized zone (DMZ) in Gyeonggi-do province, South Korea, from 2022 to 2023. Genetic diversity was investigated based on the internal transcribed spacer (ITS2), cytochrome c oxidase subunit I (COI), and knockdown resistance (kdr) genes of Anopheles mosquitoes. A natural environment associated with the seasonal abundance of Anopheles larvae was characterized. Results Two breeding sites of Anopheles larvae and adults were found at a stream margin or shallow freshwater near the forest in Wolgot-myeon in Gimpo-si without cattle shed within 1 km and in Naega-myeon in Ganghwa-gun with cow shed within 100 m in 2022 and 2023, respectively. Both sites were located between the newly cultivated lands and the forest. Besides, both breeding sites were in the valley at a slight elevation of 60–70 m from ground lands and maintained the shadow all day. Overall, the Wolgot-myeon breeding site showed various Anopheles spp. larvae, including Anopheles sinensis. Naega-myeon, an additional breeding site found in 2023, had Anopheles sineroides larvae, and approximately 59.7% (89/149) of An. sinensis adults inhabited within a 100-m distance. The total collection, including larvae and adults, revealed that An. sinensis, Anopheles pullus, Anopheles kleini, An. sineroides, Anopheles belenrae, and Anopheles lindesayi accounted for 44.2% (118/267), 0.7% (2/267), 0.7% (2/267), 22.1% (59/267), 1.9% (5/267), and 30.3% (81/267), respectively. Furthermore, various kdr mutant genotypes (F/F, C/C, L/F, L/C and F/C) in An. sinensis, and the first kdr allele mutant (L/F1014) in An. belenrae were identified in South Korea. Conclusions Two breeding sites of Anopheles larvae were studied in Wolgot-myeon and Naega-myeon. Various Anopheles spp. larvae were detected in both habitats, but overall, An. sinensis was the most prevalent adults in both study sites. The occurrence of kdr allele mutant of An. belenrae in South Korea was reported. Rigorous larvae monitoring of Anopheles spp., continuously updating information on Anopheles breeding sites, and understanding the environmental conditions of Anopheles habitats are required to develop an effective malaria control programme in South Korea.
Læs mere Tjek på PubMedLucien Platon, Didier Ménard
Trends in Parasitology, 16.12.2023
Tilføjet 16.12.2023
Malaria is a life-threatening tropical disease caused by parasites of the genus Plasmodium, of which Plasmodium falciparum is the most lethal. Malaria parasites have a complex life cycle, with stages occurring in both the Anopheles mosquito vector and human host. Ring stages are the youngest form of the parasite in the intraerythrocytic developmental cycle and are associated with evasion of spleen clearance, temporary growth arrest (TGA), and drug resistance. This formidable ability to survive and develop into mature, sexual, or growth-arrested forms demonstrates the inherent population heterogeneity. Here we highlight the role of the ring stage as a crossroads in parasite development and as a reservoir of surviving cells in the human host via TGA survival mechanisms.
Læs mere Tjek på PubMedMalaria Journal, 16.12.2023
Tilføjet 16.12.2023
Abstract In many studies to evaluate the quality of malaria diagnosis, microscopy or rapid diagnostic tests (RDT) are compared to PCR. Depending on the method for sample collection and storage (whole blood or dried blood spot), volume of blood used for extraction, volume of DNA used as PCR template, and choice of PCR target (single vs. multi-copy gene), the limit of detection (LOD) of PCR might not exceed the LOD of expert microscopy or RDT. One should not assume that PCR always detects the highest number of infections.
Læs mere Tjek på PubMedLesego, A., Tsegaye, T., Were, L. P. O., Sakvarelidze, G., Garg, S., Morrison, L., Nigussie, S., Githendu, P., Achoki, T.
BMJ Open, 15.12.2023
Tilføjet 15.12.2023
ObjectiveThe Global Fund to Fight AIDS, Tuberculosis and Malaria (Global Fund) partnered with the Ethiopian Pharmaceutical Supply Agency (EPSA) in 2018–2019 to reform procurement and supply chain management (PSCM) procedures within the Ethiopian healthcare system. This assessment sought to determine the impact of the reforms and document the lessons learnt. DesignMixed-methods study incorporating qualitative and quantitative analysis. Purposive and snowballing sampling techniques were applied for the qualitative methods, and the data collected was transcribed in full and subjected to thematic content analysis. Descriptive analysis was applied to quantitative data. SettingThe study was based in Ethiopia and focused on the EPSA operations nationally between 2017 and 2021. ParticipantsTwenty-five Ethiopian healthcare decision-makers and health workers. InterventionGlobal Fund training programme for health workers and infrastructural improvements OutcomesOperational and financial measures for healthcare PSCM. ResultsThe availability of antiretrovirals, tuberculosis and malaria medicines, and other related commodities, remained consistently high. Line fill rate and forecast accuracy were average. Between 2018 and 2021, procurement lead times for HIV and malaria-related orders reduced by 43.0% relative to other commodities that reported an increase. Many interview respondents recognised the important role of the Global Fund support in improving the performance of EPSA and provided specific attributions to the observed successes. However, they were also clear that more needs to be done in specific critical areas such as financing, strategic reorganisation, data and information management systems. ConclusionThe Global Fund-supported initiatives led to improvements in the EPSA performance, despite several persistent challenges. To sustain and secure the gains achieved so far through Global Fund support and make progress, it is important that various stakeholders, including the government and the donor community, work together to support EPSA in delivering on its core mandate within the Ethiopian health system.
Læs mere Tjek på PubMedJeanne Rini Poespoprodjo, Nicholas M Douglas, Daniel Ansong, Steven Kho, Nicholas M Anstey
Lancet, 15.12.2023
Tilføjet 15.12.2023
Malaria is resurging in many African and South American countries, exacerbated by COVID-19-related health service disruption. In 2021, there were an estimated 247 million malaria cases and 619 000 deaths in 84 endemic countries. Plasmodium falciparum strains partly resistant to artemisinins are entrenched in the Greater Mekong region and have emerged in Africa, while Anopheles mosquito vectors continue to evolve physiological and behavioural resistance to insecticides. Elimination of Plasmodium vivax malaria is hindered by impractical and potentially toxic antirelapse regimens.
Læs mere Tjek på PubMedMalaria Journal, 15.12.2023
Tilføjet 15.12.2023
Abstract Background Plasmodium knowlesi is an established experimental model for basic and pre-clinical malaria vaccine research. Historically, rhesus macaques have been the most common host for malaria vaccine studies with P. knowlesi parasites. However, rhesus are not natural hosts for P. knowlesi, and there is interest in identifying alternative hosts for vaccine research. The study team previously reported that pig-tailed macaques (PTM), a natural host for P. knowlesi, could be challenged with cryopreserved P. knowlesi sporozoites (PkSPZ), with time to blood stage infection equivalent to in rhesus. Here, additional exploratory studies were performed to evaluate PTM as potential hosts for malaria vaccine studies. The aim was to further characterize the parasitological and veterinary health outcomes after PkSPZ challenge in this macaque species. Methods Malaria-naïve PTM were intravenously challenged with 2.5 × 103 PkSPZ and monitored for blood stage infection by Plasmodium 18S rRNA RT-PCR and thin blood smears. Disease signs were evaluated by daily observations, complete blood counts, serum chemistry tests, and veterinary examinations. After anti-malarial drug treatment, a subset of animals was re-challenged and monitored as above. Whole blood gene expression analysis was performed on selected animals to assess host response to infection. Results In naïve animals, the kinetics of P. knowlesi blood stage replication was reproducible, with parasite burden rising linearly during an initial acute phase of infection from 6 to 11 days post-challenge, before plateauing and transitioning into a chronic low-grade infection. After re-challenge, infections were again reproducible, but with lower blood stage parasite densities. Clinical signs of disease were absent or mild and anti-malarial treatment was not needed until the pre-defined study day. Whole blood gene expression analysis identified immunological changes associated with acute and chronic phases of infection, and further differences between initial challenge versus re-challenge. Conclusions The ability to challenge PTM with PkSPZ and achieve reliable blood stage infections indicate this model has significant potential for malaria vaccine studies. Blood stage P. knowlesi infection in PTM is characterized by low parasite burdens and a benign disease course, in contrast with the virulent P. knowlesi disease course commonly reported in rhesus macaques. These findings identify new opportunities for malaria vaccine research using this natural host-parasite combination. Graphical Abstract
Læs mere Tjek på PubMedMalaria Journal, 13.12.2023
Tilføjet 13.12.2023
Abstract Background Mass drug administration (MDA) and indoor residual spraying (IRS) are potent malaria burden reduction tools. The impact of combining MDA and IRS is not well documented. We evaluated the impact of MDA + IRS compared to IRS alone at a high transmission site in Eastern Uganda. Methods A quasi-experimental study was implemented in Toroma and Kapujan subcounties in north eastern Uganda. Both subcounties received four rounds of IRS using primiphos-methyl (Acttellic SC300) 6–8 months apart from December 2016 to December 2018. Eligible residents of Kapujan simultaneously received MDA using dihydroartemesinin-piperaquine (DHA-PQ). Health facility data was used to monitor malaria case incidence rate and test positivity rates. Results In the MDA + IRS arm, malaria incidence dropped by 83% (IRR: 0·17 (0.16–0.18); p
Læs mere Tjek på PubMedMalaria Journal, 13.12.2023
Tilføjet 13.12.2023
Abstract Background Light microscopy and rapid diagnostic tests (RDT) have long been the recommended diagnostic methods for malaria. However, in recent years, loop-mediated isothermal amplification (LAMP) techniques have been shown to offer superior performance, in particular concerning low-grade parasitaemia, by delivering higher sensitivity and specificity with low laboratory capacity requirements in little more than an hour. In this study, the diagnostic performance of two LAMP kits were assessed head-to-head, compared to highly sensitive quantitative real time PCR (qPCR), in a non-endemic setting. Methods In this retrospective validation study two LAMP kits; Alethia® Illumigene Malaria kit and HumaTurb Loopamp™ Malaria Pan Detection (PDT) kit, were evaluated head-to-head for detection of Plasmodium-DNA in 133 biobanked blood samples from suspected malaria cases at the Clinical Microbiology Laboratory of Region Skåne, Sweden to determine their diagnostic performance compared to qPCR. Results Of the 133 samples tested, qPCR detected Plasmodium DNA in 41 samples (defined as true positives), and the two LAMP methods detected 41 and 37 of those, respectively. The results from the HumaTurb Loopamp™ Malaria PDT kit were in complete congruence with the qPCR, with a sensitivity of 100% (95% CI 91.40–100%) and specificity of 100% (95% CI 96.07–100%). The Alethia® Illumigene Malaria kit had a sensitivity of 90.24% (95% CI 76.87–97.28) and a specificity of 95.65% (95% CI 89.24–98.80) as compared to qPCR. Conclusions This head-to-head comparison showed higher performance indicators of the HumaTurb Loopamp™ Malaria PDT kit compared to the Alethia® illumigene Malaria kit for detection of malaria.
Læs mere Tjek på PubMedAngella M. George, Rashid Ansumana, Dziedzom K. de Souza, Vettakkara Kandy Muhammed Niyas, Alimuddin Zumla, Moses J Bockarie
International Journal of Infectious Diseases, 13.12.2023
Tilføjet 13.12.2023
As the world experiences warmer weather, heat waves and flooding, the climate change is leading to the geographical expansion of mosquitos, which are known vectors of a range of infectious diseases like dengue, malaria, chikungunya, yellow fever, rift valley fever, West Nile fever, Japanese encephalitis and Zika which affect millions of people worldwide (1). Climate change now threatens the spread of vector-borne diseases to previously low-risk areas in Africa, Asia, Europe, and the Americas (2-7) According to the World Health Organization (WHO), an additional 250,000 deaths per year will occur in the next decades as a result of malnutrition, heat stress and vector-borne diseases (8).
Læs mere Tjek på PubMedDanny Xuan-Rong Koh, Mohamed Afiq Hidayat Zailani, Raja Zahratul Azma Raja Sabudin, Sanggari Muniandy, Nur Awatif Akmal Muhamad Hata, Siti Noor Baya Mohd Noor, Norhazilah Zakaria, Ainoon Othman, Endom Ismail
PLoS One Infectious Diseases, 12.12.2023
Tilføjet 12.12.2023
by Danny Xuan-Rong Koh, Mohamed Afiq Hidayat Zailani, Raja Zahratul Azma Raja Sabudin, Sanggari Muniandy, Nur Awatif Akmal Muhamad Hata, Siti Noor Baya Mohd Noor, Norhazilah Zakaria, Ainoon Othman, Endom Ismail Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked genetic disorder characterized by reduced G6PD enzyme levels in the blood. This condition is common in populations exposed to malaria; an acute febrile disease caused by Plasmodium parasites. G6PD-deficient individuals may suffer from acute hemolysis following the prescription of Primaquine, an antimalarial treatment. The population at risk for such a condition includes the Senoi group of Orang Asli, a remote indigenous community in Malaysia. This study aimed to elucidate the G6PD molecular heterogeneity in this subethnic group which is important for malaria elimination. A total of 662 blood samples (369 males and 293 females) from the Senoi subethnic group were screened for G6PD deficiency using a quantitative G6PD assay, OSMMR2000-D kit with Hb normalization. After excluding the family members, the overall prevalence of G6PD deficiency in the studied population was 15.2% (95% CI: 11–19%; 56 of 369), with males (30 of 172; 17.4%) outnumbering females (26 of 197; 13.2%). The adjusted male median (AMM), defined as 100% G6PD activity, was 11.8 IU/gHb. A total of 36 participants (9.6%; 26 male and 10 female) were deficient (G)(39.1%; n = 34), G6PD Viangchan (c.871G>A)(25.3%; n = 22), G6PD Union (c.1360C>T)(21.8%; n = 19), c.1311C>T(20.7%; n = 18), G6PD Kaiping (c.1388G>A)(8.0%; n = 7), and G6PD Coimbra (c.592C>T)(2.3%; n = 2). Our analysis revealed 27 hemizygote males, 18 heterozygote females, 7 homozygote females, and 2 compound heterozygote females. This study confirms the high prevalence of G6PD deficiency among the Senoi Malaysian Orang Asli, with a significant degree of molecular heterogeneity. More emphasis should be placed on screening for G6PD status and proper and safe use of Primaquine in the elimination of malaria among this indigenous population.
Læs mere Tjek på PubMedMalaria Journal, 12.12.2023
Tilføjet 12.12.2023
Abstract Background Plasmodium falciparum genetic diversity can add information on transmission intensity and can be used to track control and elimination interventions. Methods Dried blood spots (DBS) were collected from patients who were recruited for a P. falciparum malaria therapeutic efficacy trial in three malaria endemic sites in Ethiopia from October to December 2015, and November to December 2019. qPCR-confirmed infections were subject to amplicon sequencing of polymorphic markers ama1-D3, csp, cpp, cpmp, msp7. Genetic diversity, the proportion of multiclonal infections, multiplicity of infection, and population structure were analysed. Results Among 198 samples selected for sequencing, data was obtained for 181 samples. Mean MOI was 1.38 (95% CI 1.24–1.53) and 17% (31/181) of infections were polyclonal. Mean He across all markers was 0.730. Population structure was moderate; populations from Metema and Metehara 2015 were very similar to each other, but distinct from Wondogent 2015 and Metehara 2019. Conclusion The high level of parasite genetic diversity and moderate population structure in this study suggests frequent gene flow of parasites among sites. The results obtained can be used as a baseline for additional parasite genetic diversity and structure studies, aiding in the formulation of appropriate control strategies in Ethiopia.
Læs mere Tjek på PubMedMalaria Journal, 11.12.2023
Tilføjet 11.12.2023
Abstract Background Resistance against artemisinin-based combination therapy is one of the challenges to malaria control and elimination globally. Mutations in different genes (Pfdhfr, Pfdhps, Pfk-13 and Pfmdr1) confer resistance to artesunate and sulfadoxine–pyrimethamine (AS + SP) were analysed from Mandla district, Madhya Pradesh, to assess the effectiveness of the current treatment regimen against uncomplicated Plasmodium falciparum. Methods Dried blood spots were collected during the active fever survey and mass screening and treatment activities as part of the Malaria Elimination Demonstration Project (MEDP) from 2019 to 2020. Isolated DNA samples were used to amplify the Pfdhfr, Pfdhps, Pfk13 and Pfmdr1 genes using nested PCR and sequenced for mutation analysis using the Sanger sequencing method. Results A total of 393 samples were subjected to PCR amplification, sequencing and sequence analysis; 199, 215, 235, and 141 samples were successfully sequenced for Pfdhfr, Pfdhps, Pfk13, Pfmdr1, respectively. Analysis revealed that the 53.3% double mutation (C59R, S108N) in Pfdhfr, 89.3% single mutation (G437A) in Pfdhps, 13.5% single mutants (N86Y), and 51.1% synonymous mutations in Pfmdr1 in the study area. Five different non-synonymous and two synonymous point mutations found in Pfk13, which were not associated to artemisinin resistance. Conclusion The study has found that mutations linked to SP resistance are increasing in frequency, which may reduce the effectiveness of this drug as a future partner in artemisinin-based combinations. No evidence of mutations linked to artemisinin resistance in Pfk13 was found, suggesting that parasites are sensitive to artemisinin derivatives in the study area. These findings are a baseline for routine molecular surveillance to proactively identify the emergence and spread of artemisinin-resistant parasites.
Læs mere Tjek på PubMedInfectious Disease Modelling, 10.12.2023
Tilføjet 10.12.2023
Publication date: Available online 9 December 2023 Source: Infectious Disease Modelling Author(s): Francis Oketch Ochieng
Læs mere Tjek på PubMedMalaria Journal, 10.12.2023
Tilføjet 10.12.2023
Abstract Background Malaria is a major global health challenge, and for the elimination and eradication of this disease, transmission-blocking vaccines (TBVs) are a priority. Plasmodium falciparum Generative Cell Specific 1 (PfGCS1), a promising TBV candidate, is essential for gamete fertilization. The HAP2-GCS1 domain of this antigen as well as its cd loop could induce antibodies that partially inhibit transmission of P. falciparum. Methods In the current study, a new synthetic fusion antigen containing cd loop and HAP2-GCS1 domain (cd-HAP) of PfGCS1 was evaluated as a transmission blocking vaccine candidate. Initially, the profile of naturally acquired IgG antibodies to the cd-HAP antigen was analysed in Iranian individuals infected with P. falciparum, to confirm that this new fusion protein has the appropriate structure containing common epitopes with the native form of PfGCS1. Then, the immunogenicity of cd-HAP was evaluated in BALB/c mice, using different adjuvant systems such as CpG, MPL, QS-21, and a combination of them (CMQ). Furthermore, the blocking efficacy of polyclonal antibodies induced against these formulations was also assessed by oocyst intensity and infection prevalence in the Standard Membrane Feeding Assay (SMFA). Results The naturally acquired antibodies (dominantly IgG1 and IgG3 subclasses) induced in P. falciparum-infected individuals could recognize the cd-HAP antigen which implies that the new fusion protein has a proper conformation that mimics the native structure of PfGCS1. Concerning the immunogenicity of cd-HAP antigen, the highest IgG levels and titers, by a Th1-type immune profile, and elevated antibody avidity were induced in mice immunized with the cd-HAP antigen formulated with a combination of adjuvants (P
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