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PLoS Neglected Tropical Diseases Feb 2018Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes...
BACKGROUND
Among the Plasmodium species that infect humans, adverse effects of P. falciparum and P. vivax have been extensively studied and reported with respect to poor outcomes particularly in first time mothers and in pregnant women living in areas with unstable malaria transmission. Although, other non-falciparum malaria infections during pregnancy have sometimes been reported, little is known about the dynamics of these infections during pregnancy.
METHODS AND FINDINGS
Using a quantitative PCR approach, blood samples collected from Beninese pregnant women during the first antenatal visit (ANV) and at delivery including placental blood were screened for Plasmodium spp. Risk factors associated with Plasmodium spp. infection during pregnancy were assessed as well as the relationships with pregnancy outcomes. P. falciparum was the most prevalent Plasmodium species detected during pregnancy, irrespective either of parity, of age or of season during which the infection occurred. Although no P. vivax infections were detected in this cohort, P. malariae (9.2%) and P. ovale (5.8%) infections were observed in samples collected during the first ANV. These non-falciparum infections were also detected in maternal peripheral blood (1.3% for P. malariae and 1.2% for P. ovale) at delivery. Importantly, higher prevalence of P. malariae (5.5%) was observed in placental than peripheral blood while that of P. ovale was similar (1.8% in placental blood). Among the non-falciparum infected pregnant women with paired peripheral and placental samples, P. malariae infections in the placental blood was significantly higher than in the peripheral blood, suggesting a possible affinity of P. malariae for the placenta. However, no assoctiation of non-falciparum infections and the pregnancy outcomes was observed.
CONCLUSIONS
Overall this study provided insights into the molecular epidemiology of Plasmodium spp. infection during pregnancy, indicating placental infection by non-falciparum Plasmodium and the lack of association of these infections with adverse pregnancy outcomes.
Topics: Benin; Blood; Female; Humans; Malaria; Molecular Epidemiology; Placenta; Placenta Diseases; Plasmodium; Pregnancy; Pregnancy Complications, Infectious; Pregnancy Outcome; Real-Time Polymerase Chain Reaction; Risk Factors
PubMed: 29432484
DOI: 10.1371/journal.pntd.0006279 -
The Korean Journal of Parasitology Jun 2009Malaria is a major cause of death in tropical and sub-tropical countries, killing each year over 1 million people globally; 90% of fatalities occur in African children.... (Review)
Review
Malaria is a major cause of death in tropical and sub-tropical countries, killing each year over 1 million people globally; 90% of fatalities occur in African children. Although effective ways to manage malaria now exist, the number of malaria cases is still increasing, due to several factors. In this emergency situation, prompt and effective diagnostic methods are essential for the management and control of malaria. Traditional methods for diagnosing malaria remain problematic; therefore, new technologies have been developed and introduced to overcome the limitations. This review details the currently available diagnostic methods for malaria.
Topics: Animals; Humans; Malaria; Plasmodium
PubMed: 19488414
DOI: 10.3347/kjp.2009.47.2.93 -
Future Microbiology Nov 2011Malaria parasites have evolved a complicated life cycle alternating between two hosts. Gametocytes are produced in the vertebrate hosts and are obligatory for natural... (Review)
Review
Malaria parasites have evolved a complicated life cycle alternating between two hosts. Gametocytes are produced in the vertebrate hosts and are obligatory for natural transmission of the parasites through mosquito vectors. The mechanism of sexual development in Plasmodium has been the focus of extensive studies. In the postgenomic era, the advent of genome-wide analytical tools and genetic manipulation technology has enabled rapid advancement of our knowledge in this area. Patterns of gene expression during sexual development, molecular distinction of the two sexes, and mechanisms underlying subsequent formation of gametes and their fertilization have been progressively elucidated. However, the triggers and mechanism of sexual development remain largely unknown. This article provides an update of our understanding of the molecular and cellular events associated with the decision for commitment to sexual development and regulation of gene expression during gametocytogenesis. Insights into the molecular mechanisms of gametocyte development are essential for designing proper control strategies for interruption of malaria transmission and ultimate elimination.
Topics: Animals; Culicidae; Gene Expression Regulation; Humans; Plasmodium
PubMed: 22082293
DOI: 10.2217/fmb.11.108 -
Parasite (Paris, France) 2020Microsatellites can be utilized to explore genotypes, population structure, and other genomic features of eukaryotes. Systematic characterization of microsatellites has...
Microsatellites can be utilized to explore genotypes, population structure, and other genomic features of eukaryotes. Systematic characterization of microsatellites has not been a focus for several species of Plasmodium, including P. malariae and P. ovale, as the majority of malaria elimination programs are focused on P. falciparum and to a lesser extent P. vivax. Here, five human malaria species (P. falciparum, P. vivax, P. malariae, P. ovale curtisi, and P. knowlesi) were investigated with the aim of conducting in-depth categorization of microsatellites for P. malariae and P. ovale curtisi. Investigation of reference genomes for microsatellites with unit motifs of 1-10 base pairs indicates high diversity among the five Plasmodium species. Plasmodium malariae, with the largest genome size, displays the second highest microsatellite density (1421 No./Mbp; 5% coverage) next to P. falciparum (3634 No./Mbp; 12% coverage). The lowest microsatellite density was observed in P. vivax (773 No./Mbp; 2% coverage). A, AT, and AAT are the most commonly repeated motifs in the Plasmodium species. For P. malariae and P. ovale curtisi, microsatellite-related sequences are observed in approximately 18-29% of coding sequences (CDS). Lysine, asparagine, and glutamic acids are most frequently coded by microsatellite-related CDS. The majority of these CDS could be related to the gene ontology terms "cell parts," "binding," "developmental processes," and "metabolic processes." The present study provides a comprehensive overview of microsatellite distribution and can assist in the planning and development of potentially useful genetic tools for further investigation of P. malariae and P. ovale curtisi epidemiology.
Topics: Gene Ontology; Genome, Protozoan; Genotype; Microsatellite Repeats; Plasmodium; Plasmodium malariae; Plasmodium ovale; Tandem Repeat Sequences
PubMed: 32410726
DOI: 10.1051/parasite/2020034 -
Parasites & Vectors May 2022Parasites interact with their host through "direct" and/or "indirect" mechanisms. Plasmodium, for example, either mediates direct physical interactions with host factors...
BACKGROUND
Parasites interact with their host through "direct" and/or "indirect" mechanisms. Plasmodium, for example, either mediates direct physical interactions with host factors or triggers the immune system of the host indirectly, leading to changes in infectious outcomes. Long non-coding RNAs (lncRNAs) participate in regulating biological processes, especially host-pathogen interactions. However, research on the role of host lncRNAs during Plasmodium infection is limited.
METHODS
A RNA sequencing method (RNA-seq) was used to confirm the differential expression profiles of lncRNAs in Plasmodium yeolii 17XL (P.y17XL)-infected BALB/c mice. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to elucidate the potential functions of Plasmodium-induced genes. Subsequently, the effect of specific lncRNAs on the modulation of immune-related signaling pathways in malaria was determined by fluorescence-activated cell sorting, western blot and enzyme-linked immunosorbent assay.
RESULTS
The data showed that in P.y17XL-infected BALB/c mice, Plasmodium upregulated the expression of 132 lncRNAs and downregulated the expression of 159 lncRNAs. Differentially expressed lncRNAs clearly associated with malaria infection were annotated, including four novel dominant lncRNAs: ENMSUSG00000111521.1, XLOC_038009, XLOC_058629 and XLOC_065676. GO and KEGG pathway analyses demonstrated that these four differentially expressed lncRNAs were associated with co-localized/co-expressed protein-coding genes that were totally enriched in malaria and with the transforming growth factor beta (TGF-β) signaling pathway. Using the models of P.y17XL-infected BALB/c mice, data certified that the level of TGF-β production and activation of TGF-β/Smad signaling pathway were obviously changed in malaria infection.
CONCLUSIONS
These differentially expressed immune-related genes were deemed to have a role in the process of Plasmodium infection in the host via dendritic/T regulatory cells and the TGF-β/Smad signaling pathway. The results of the present study confirmed that Plasmodium infection-induced lncRNA expression is a novel mechanism used by Plasmodium parasites to modify host immune signaling. These results further enhance current understanding of the interaction between Plasmodium and host cells.
Topics: Animals; Erythrocytes; Mice; Plasmodium; RNA, Long Noncoding; RNA, Messenger; Transforming Growth Factor beta
PubMed: 35643541
DOI: 10.1186/s13071-022-05298-4 -
Parasitology Feb 2015SUMMARY Malaria remains one of the most significant global public health burdens, with nearly half of the world's population at risk of infection. Malaria is not however... (Review)
Review
SUMMARY Malaria remains one of the most significant global public health burdens, with nearly half of the world's population at risk of infection. Malaria is not however a monolithic disease - it can be caused by multiple different parasite species of the Plasmodium genus, each of which can induce different symptoms and pathology, and which pose quite different challenges for control. Furthermore, malaria is in no way restricted to humans. There are Plasmodium species that have adapted to infect most warm-blooded vertebrate species, and the genus as a whole is both highly successful and highly diverse. How, where and when human malaria parasites originated from within this diversity has long been a subject of fascination and sometimes also controversy. The past decade has seen the publication of a number of important discoveries about malaria parasite origins, all based on the application of molecular diagnostic tools to new sources of samples. This review summarizes some of those recent discoveries and discusses their implication for our current understanding of the origin and evolution of the Plasmodium genus. The nature of these discoveries and the manner in which they are made are then used to lay out a series of opportunities and challenges for the next wave of parasite hunters.
Topics: Biological Evolution; Host-Parasite Interactions; Humans; Malaria; Phylogeny; Plasmodium
PubMed: 24963725
DOI: 10.1017/S0031182014000766 -
Molecular and Biochemical Parasitology Jul 2021Malaria parasites exhibit a complex lifecycle, requiring extensive asexual replication in the liver and blood of the vertebrate host, and in the haemocoel of the insect... (Review)
Review
Malaria parasites exhibit a complex lifecycle, requiring extensive asexual replication in the liver and blood of the vertebrate host, and in the haemocoel of the insect vector. Yet, they must also undergo a single round of sexual reproduction, which occurs in the vector's midgut upon uptake of a blood meal. Sexual reproduction is obligate for infection of the vector and thus, is essential for onwards transmission to new hosts. Sex in malaria parasites involves several bottlenecks in parasite number, making the stages involved attractive targets for blocking disease transmission. Malaria parasites have evolved a suite of adaptations ("strategies") to maximise the success of sexual reproduction and transmission, which could undermine transmission-blocking interventions. Yet, understanding parasite strategies may also reveal novel opportunities for such interventions. Here, we outline how evolutionary and ecological theories, developed to explain reproductive strategies in multicellular taxa, can be applied to explain two reproductive strategies (conversion rate and sex ratio) expressed by malaria parasites within the vertebrate host.
Topics: Animals; Biological Coevolution; Culicidae; Erythrocytes; Female; Gametogenesis; Host-Parasite Interactions; Humans; Insect Vectors; Life Cycle Stages; Liver; Malaria; Male; Plasmodium berghei; Plasmodium chabaudi; Plasmodium falciparum; Plasmodium knowlesi; Reproduction, Asexual; Sex Ratio
PubMed: 34023299
DOI: 10.1016/j.molbiopara.2021.111375 -
Malaria Journal Mar 2019The Belgian Reference Laboratory for Plasmodium offers a free-of-charge reference testing of malaria-positive or doubtful samples to clinical laboratories.
BACKGROUND
The Belgian Reference Laboratory for Plasmodium offers a free-of-charge reference testing of malaria-positive or doubtful samples to clinical laboratories.
METHODS
The final malaria diagnosis from the Reference Laboratory (microscopy, rapid diagnostic tests (RDTs) and Plasmodium species-specific PCR) were compared with the final diagnosis from peripheral Belgian laboratories. The Reference Laboratory reports were analysed for all samples submitted between 2013 and 2017. Criteria assessed included the diagnosis of malaria, Plasmodium species identification including mixed infections, and in case of Plasmodium falciparum, the parasite density and the presence of sexual and asexual stages.
RESULTS
A total of 947 non-duplicate samples were included. Reference testing confirmed 96.3% (893/927) and 90.0% (18/20) samples submitted as positive and negative, respectively, the two missed diagnoses were samples with Plasmodium ovale and Plasmodium malariae. Submitting laboratories had correctly identified P. falciparum in 95.1% (508/534) samples with P. falciparum single infection. They had correctly diagnosed the species in 62.9% (95/151) single non-falciparum samples and had reported 'non-falciparum' in another 26 (17.2%) samples; most errors occurred among P. malariae (n = 8/21, 38.1%) and P. ovale (n = 14/51, 27.5%). Only one of the 21 mixed Plasmodium species infections had been diagnosed as such by the submitting laboratories; in three of them, P. falciparum had been overlooked. Taken single and mixed infections together, P. falciparum was diagnosed in 98.6% (546/554) samples. Among 471 single P. falciparum samples available for comparison, laboratories had correctly reported parasite densities above 2% in 87.5% (70/80) samples; they had incorrectly reported parasite densities > 2% in an extra 52 (8.9%) samples. Laboratories had correctly reported P. falciparum schizonts and gametocytes in 25.6% (11/43) and 56.7% (17/30) samples, respectively.
CONCLUSION
Diagnostic laboratories in a malaria non-endemic setting provided excellent diagnosis of malaria and P. falciparum, reasonably good diagnosis of non-falciparum infections and acceptable calculation of P. falciparum parasite density.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Belgium; Child; Child, Preschool; Clinical Laboratory Techniques; Female; Humans; Infant; Laboratory Proficiency Testing; Malaria; Male; Middle Aged; Parasite Load; Plasmodium; Young Adult
PubMed: 30922316
DOI: 10.1186/s12936-019-2731-0 -
Infection, Genetics and Evolution :... Aug 2021Plasmodium parasites, the cause of malaria, have a complex life cycle, infecting alternatively vertebrate hosts and female Anopheles mosquitoes and undergoing intra- and...
Plasmodium parasites, the cause of malaria, have a complex life cycle, infecting alternatively vertebrate hosts and female Anopheles mosquitoes and undergoing intra- and extra-cellular development in several organs of these hosts. Most of the ~5000 protein-coding genes present in Plasmodium genomes are only expressed at specific life stages, and different genes might therefore be subject to different selective pressures depending on the biological activity of the parasite and its microenvironment at this point in development. Here, we estimate the selective constraints on the protein-coding sequences of all annotated genes of rodent and primate Plasmodium parasites and, using data from scRNA-seq experiments spanning many developmental stages, analyze their variation with regard to when these genes are expressed in the parasite life cycle. Our study reveals extensive variation in selective constraints throughout the parasites' development and highlights stages that are evolving more rapidly than others. These findings provide novel insights into the biology of these parasites and could provide important information to develop better treatment strategies or vaccines against these medically-important organisms.
Topics: Animals; Ape Diseases; Life Cycle Stages; Malaria; Monkey Diseases; Plasmodium; Selection, Genetic
PubMed: 33975022
DOI: 10.1016/j.meegid.2021.104908 -
Molecular Microbiology May 2021Parasites of the genus Plasmodium, the etiological agent of malaria, are transmitted through the bite of anopheline mosquitoes, which deposit sporozoites into the host... (Review)
Review
Parasites of the genus Plasmodium, the etiological agent of malaria, are transmitted through the bite of anopheline mosquitoes, which deposit sporozoites into the host skin. Sporozoites migrate through the dermis, enter the bloodstream, and rapidly traffic to the liver. They cross the liver sinusoidal barrier and traverse several hepatocytes before switching to productive invasion of a final one for replication inside a parasitophorous vacuole. Cell traversal and productive invasion are functionally independent processes that require proteins secreted from specialized secretory organelles known as micronemes. In this review, we summarize the current understanding of how sporozoites traverse through cells and productively invade hepatocytes, and discuss the role of environmental sensing in switching from a migratory to an invasive state. We propose that timely controlled secretion of distinct microneme subsets could play a key role in successful migration and infection of hepatocytes. A better understanding of these essential biological features of the Plasmodium sporozoite may contribute to the development of new strategies to fight against the very first and asymptomatic stage of malaria.
Topics: Animals; Hepatocytes; Humans; Liver; Malaria; Plasmodium; Sporozoites
PubMed: 33191548
DOI: 10.1111/mmi.14645