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Malaria Journal May 2021Loop-mediated isothermal amplification (LAMP) for malaria diagnosis at the point of care (POC) depends on the detection capacity of synthesized nucleic acids and the...
BACKGROUND
Loop-mediated isothermal amplification (LAMP) for malaria diagnosis at the point of care (POC) depends on the detection capacity of synthesized nucleic acids and the specificity of the amplification target. To improve malaria diagnosis, new colorimetric LAMP tests were developed using multicopy targets for Plasmodium vivax and Plasmodium falciparum detection.
METHODS
The cytochrome oxidase I (COX1) mitochondrial gene and the non-coding sequence Pvr47 for P. vivax, and the sub-telomeric sequence of erythrocyte membrane protein 1 (EMP1) and the non-coding sequence Pfr364 for P. falciparum were targeted to design new LAMP primers. The limit of detection (LOD) of each colorimetric LAMP was established and assessed with DNA extracted by mini spin column kit and the Boil & Spin method from 28 microscopy infections, 101 malaria submicroscopic infections detected by real-time PCR only, and 183 negatives infections by both microscopy and PCR.
RESULTS
The LODs for the colorimetric LAMPs were estimated between 2.4 to 3.7 parasites/µL of whole blood. For P. vivax detection, the colorimetric LAMP using the COX1 target showed a better performance than the Pvr47 target, whereas the Pfr364 target was the most specific for P. falciparum detection. All microscopic infections of P. vivax were detected by PvCOX1-LAMP using the mini spin column kit DNA extraction method and 81% (17/21) were detected using Boil & Spin sample preparation. Moreover, all microscopic infections of P. falciparum were detected by Pfr364-LAMP using both sample preparation methods. In total, PvCOX1-LAMP and Pfr364-LAMP detected 80.2% (81 samples) of the submicroscopic infections using the DNA extraction method by mini spin column kit, while 36.6% (37 samples) were detected using the Boil & Spin sample preparation method.
CONCLUSION
The colorimetric LAMPs with multicopy targets using the COX1 target for P. vivax and the Pfr364 for P. falciparum have a high potential to improve POC malaria diagnosis detecting a greater number of submicroscopic Plasmodium infections.
Topics: Colorimetry; Electron Transport Complex IV; Malaria, Falciparum; Malaria, Vivax; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Plasmodium falciparum; Plasmodium vivax; Protozoan Proteins
PubMed: 34011373
DOI: 10.1186/s12936-021-03753-8 -
Frontiers in Cellular and Infection... 2021The control and elimination of malaria caused by both represent a great challenge due to the biological aspects of the species. Gametocytes are the forms responsible...
The control and elimination of malaria caused by both represent a great challenge due to the biological aspects of the species. Gametocytes are the forms responsible for the transmission of the parasite to the vector and the search for new strategies for blocking transmission are essential in a scenario of control and elimination The challenges in this search in regard to mainly stem from the lack of a long-term culture and the limitation of studies of gametocytes. This study evaluated the viability and infectivity of gametocytes in short-term culture. The samples enriched in gametocytes using Percoll (i), using magnetic-activated cell sorting (MACS) (ii), and using non-enriched samples (iii) were evaluated. After the procedures, gametocytes were cultured in IMDM medium for up to 48 h. Cultured gametocytes were viable and infectious for up to 48 h, however differences in viability and infectivity were observed in the samples after 12 h of culture in relation to 0 h. Percoll-enriched samples were shown to be viable in culture for longer intervals than those purified using MACS. Gametocyte viability after enrichment procedures and short-term culture may provide new avenues in the development of methods for evaluating TB.
Topics: Humans; Malaria; Malaria, Vivax; Plasmodium falciparum; Plasmodium vivax
PubMed: 34141630
DOI: 10.3389/fcimb.2021.676276 -
Trends in Parasitology Aug 2022Currently recommended methods of assessing the efficacy of uncomplicated falciparum malaria treatment work less well in high-transmission than in low-transmission... (Review)
Review
Currently recommended methods of assessing the efficacy of uncomplicated falciparum malaria treatment work less well in high-transmission than in low-transmission settings. There is also uncertainty how to assess intermittent preventive therapies and seasonal malaria chemoprevention (SMC), and Plasmodium vivax radical cure. A pharmacometric antimalarial resistance monitoring (PARM) approach is proposed specifically for evaluating slowly eliminated antimalarial drugs in areas of high transmission. In PARM antimalarial drug concentrations at recurrent parasitaemia are measured to identify outliers (i.e., recurrent parasitaemias in the presence of normally suppressive drug concentrations) and to evaluate changes over time. PARM requires characterization of pharmacometric profiles but should be simpler and more sensitive than current molecular genotyping-based methodologies. PARM does not require parasite genotyping and can be applied to the assessment of both prevention and treatment.
Topics: Antimalarials; Drug Resistance; Humans; Malaria; Malaria, Falciparum; Malaria, Vivax; Parasitemia; Plasmodium falciparum; Plasmodium vivax
PubMed: 35680541
DOI: 10.1016/j.pt.2022.05.008 -
Frontiers in Cellular and Infection... 2023China has now achieved the elimination of malaria, but it still faces severe challenges in the post-elimination stage. China continues to be plagued by imported malaria... (Review)
Review
China has now achieved the elimination of malaria, but it still faces severe challenges in the post-elimination stage. China continues to be plagued by imported malaria cases, and preventing re-transmission of imported malaria is critical. The effectiveness of antimalarial drugs for malaria control largely depends on the study of drug resistance markers . Monitoring molecular markers of parasite-associated drug resistance can help predict and manage drug resistance. There is currently a lack of systematic reviews of molecular markers for indigenous and imported malaria in China. Therefore, this review summarizes the published articles related to molecular marker polymorphism of indigenous and imported malaria cases in China in the past two decades, to study the mutation frequency and distribution of , , , and gene resistance-related loci. This can provide a whole picture of molecular markers and the resistance mutations of imported cases in China, which has certain significance for drug resistance surveillance planning, safe and effective treatment, and preventing the recurrence of local transmission by imported malaria in China in the future.
Topics: Humans; Plasmodium falciparum; Plasmodium vivax; Systematic Reviews as Topic; Malaria; Drug Resistance; China; Malaria, Falciparum; Protozoan Proteins
PubMed: 37228664
DOI: 10.3389/fcimb.2023.1167220 -
Parasite (Paris, France) 2023This study aimed to perform morphological and molecular analyses of parasites isolated from the blood of malaria-infected individuals during an outbreak in the...
This study aimed to perform morphological and molecular analyses of parasites isolated from the blood of malaria-infected individuals during an outbreak in the Microregion of Cametá, State of Pará, Brazilian Amazon. A total of 260 positive samples were identified by microscopy as Plasmodium vivax; however, in three samples, forms considered unusual for the species were found and defined as morphological atypia of P. vivax. Single P. vivax infection was confirmed by qPCR in all samples. Among 256 genotyped samples, the VK247 genotype alone was identified in 255 samples, and the VK210 genotype was found in only one. The study showed that this malaria outbreak was caused by the etiological agent P. vivax, and for the first time, morphological atypia was described in isolates circulating in Brazil. Likewise, for the first time, the VK247 genotype was detected predominantly in single infections in an area of the State of Pará, which may suggest a greater circulation of the genotype in the region.
Topics: Humans; Plasmodium vivax; Brazil; Protozoan Proteins; Malaria, Vivax; Malaria
PubMed: 37772844
DOI: 10.1051/parasite/2023039 -
Malaria Journal May 2022The global malaria burden sometimes obscures that the genus Plasmodium comprises diverse clades with lineages that independently gave origin to the extant human... (Review)
Review
The global malaria burden sometimes obscures that the genus Plasmodium comprises diverse clades with lineages that independently gave origin to the extant human parasites. Indeed, the differences between the human malaria parasites were highlighted in the classical taxonomy by dividing them into two subgenera, the subgenus Plasmodium, which included all the human parasites but Plasmodium falciparum that was placed in its separate subgenus, Laverania. Here, the evolution of Plasmodium in primates will be discussed in terms of their species diversity and some of their distinct phenotypes, putative molecular adaptations, and host-parasite biocenosis. Thus, in addition to a current phylogeny using genome-level data, some specific molecular features will be discussed as examples of how these parasites have diverged. The two subgenera of malaria parasites found in primates, Plasmodium and Laverania, reflect extant monophyletic groups that originated in Africa. However, the subgenus Plasmodium involves species in Southeast Asia that were likely the result of adaptive radiation. Such events led to the Plasmodium vivax lineage. Although the Laverania species, including P. falciparum, has been considered to share "avian characteristics," molecular traits that were likely in the common ancestor of primate and avian parasites are sometimes kept in the Plasmodium subgenus while being lost in Laverania. Assessing how molecular traits in the primate malaria clades originated is a fundamental science problem that will likely provide new targets for interventions. However, given that the genus Plasmodium is paraphyletic (some descendant groups are in other genera), understanding the evolution of malaria parasites will benefit from studying "non-Plasmodium" Haemosporida.
Topics: Animals; Malaria; Malaria, Falciparum; Plasmodium; Plasmodium falciparum; Plasmodium vivax
PubMed: 35505356
DOI: 10.1186/s12936-022-04130-9 -
The Journal of Clinical Investigation Jun 2020Plasmodium vivax bench research greatly lags behind Plasmodium falciparum because of an inability to culture in vitro. A century ago, intentionally inducing a malaria...
Plasmodium vivax bench research greatly lags behind Plasmodium falciparum because of an inability to culture in vitro. A century ago, intentionally inducing a malaria infection was a strategy commonly used to cure late-stage syphilis. These controlled human malaria infections were used with expertise and persisted to the end of World War II. While controlled malaria liver-stage infection has been achieved for both P. vivax and P. falciparum, controlled human transmission to mosquitoes falls short for both species. In this issue of the JCI, Collins et al. present groundbreaking work that establishes a system to transmit P. vivax gametocytes from humans to mosquitoes. The authors injected a unique human isolate of P. vivax that reached high gametocyte density within weeks. This study provides a technical advance that will facilitate the study and eradication of the human parasite P. vivax.
Topics: Animals; Culicidae; Humans; Malaria, Falciparum; Malaria, Vivax; Plasmodium falciparum; Plasmodium vivax
PubMed: 32338643
DOI: 10.1172/JCI135794 -
The American Journal of Tropical... Nov 2021Plasmodium falciparum and Plasmodium vivax are co-endemic in Ethiopia. This study investigated whether mixed infections were missed by microscopy from a 2017 therapeutic...
Plasmodium falciparum and Plasmodium vivax are co-endemic in Ethiopia. This study investigated whether mixed infections were missed by microscopy from a 2017 therapeutic efficacy study at two health facilities in Ethiopia. All patients (N = 304) were initially classified as having single-species P. falciparum (n = 148 samples) or P. vivax infections (n = 156). Dried blood spots were tested for Plasmodium antigens by bead-based multiplex assay for pan-Plasmodium aldolase, pan-Plasmodium lactate dehydrogenase, P. vivax lactate dehydrogenase, and histidine-rich protein 2. Of 304 blood samples, 13 (4.3%) contained both P. falciparum and P. vivax antigens and were analyzed by polymerase chain reaction for species-specific DNA. Of these 13 samples, five were confirmed by polymerase chain reaction for P. falciparum/P. vivax co-infection. One sample, initially classified as P. vivax by microscopy, was found to only have Plasmodium ovale DNA. Plasmodium falciparum/P. vivax mixed infections can be missed by microscopy even in the context of a therapeutic efficacy study with multiple trained readers.
Topics: Adolescent; Child; Child, Preschool; Coinfection; DNA, Protozoan; Disease Eradication; Ethiopia; Female; Humans; Malaria, Falciparum; Malaria, Vivax; Male; Plasmodium falciparum; Plasmodium vivax; Young Adult
PubMed: 34847530
DOI: 10.4269/ajtmh.21-0796 -
PLoS Neglected Tropical Diseases Jul 2022Genotyping Plasmodium vivax relapses can provide insights into hypnozoite biology. We performed targeted amplicon sequencing of 127 relapses occurring in Indonesian...
Genotyping Plasmodium vivax relapses can provide insights into hypnozoite biology. We performed targeted amplicon sequencing of 127 relapses occurring in Indonesian soldiers returning to malaria-free Java after yearlong deployment in malarious Eastern Indonesia. Hepatic carriage of multiple hypnozoite clones was evident in three-quarters of soldiers with two successive relapses, yet the majority of relapse episodes only displayed one clonal population. The number of clones detected in relapse episodes decreased over time and through successive relapses, especially in individuals who received hypnozoiticidal therapy. Interrogating the multiplicity of infection in this P. vivax relapse cohort reveals evidence of independent activation and slow depletion of hypnozoites over many months by multiple possible mechanisms, including parasite senescence and host immunity.
Topics: Animals; Antimalarials; Humans; Malaria; Malaria, Vivax; Parasites; Plasmodium vivax; Recurrence
PubMed: 35867730
DOI: 10.1371/journal.pntd.0010648 -
PLoS Neglected Tropical Diseases Dec 2022A key characteristic of Plasmodium vivax parasites is their ability to adopt a latent liver-stage form called hypnozoites, able to cause relapse of infection months or... (Clinical Trial)
Clinical Trial
A key characteristic of Plasmodium vivax parasites is their ability to adopt a latent liver-stage form called hypnozoites, able to cause relapse of infection months or years after a primary infection. Relapses of infection through hypnozoite activation are a major contributor to blood-stage infections in P vivax endemic regions and are thought to be influenced by factors such as febrile infections which may cause temporary changes in hypnozoite activation leading to 'temporal heterogeneity' in reactivation risk. In addition, immunity and variation in exposure to infection may be longer-term characteristics of individuals that lead to 'population heterogeneity' in hypnozoite activation. We analyze data on risk of P vivax in two previously published data sets from Papua New Guinea and the Thailand-Myanmar border region. Modeling different mechanisms of reactivation risk, we find strong evidence for population heterogeneity, with 30% of patients having almost 70% of all P vivax infections. Model fitting and data analysis indicates that individual variation in relapse risk is a primary source of heterogeneity of P vivax risk of recurrences. Trial Registration: ClinicalTrials.gov NCT01640574, NCT01074905, NCT02143934.
Topics: Animals; Humans; Chronic Disease; Liver; Malaria, Vivax; Parasites; Plasmodium vivax; Recurrence
PubMed: 36534705
DOI: 10.1371/journal.pntd.0010990