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Malaria Journal Sep 2022Haemoproteus is a sister genus to malaria parasites (Plasmodium), which both belong to the order Haemosporida (Apicomplexa). Parasites of both genera are flourishing in... (Review)
Review
BACKGROUND
Haemoproteus is a sister genus to malaria parasites (Plasmodium), which both belong to the order Haemosporida (Apicomplexa). Parasites of both genera are flourishing in birds, however, Haemoproteus species are noticeably less investigated. This is unfortunate because knowledge about close relatives of malaria pathogens is important for better understanding the evolutionary origin and basic biological features of the entire group of haemosporidian infections. Moreover, recent findings show that Haemoproteus species can cause severe damage of various bird organs due to megalomeronts and other exo-erythrocytic stages. These haemosporidians are remarkably diverse, but remain neglected partly due to difficulties in species identification. Hundreds of Haemoproteus genetic lineages have been reported in birds, and numerous new lineages are found each year, but most remain unidentified to the species level. Numerous new Haemoproteus pathogens were described during the past 20 years. However, keys for their identification are absent. Identification of Haemoproteus species remains a difficult task and is an obstacle for better understanding of the distribution and epidemiology of these parasites. This study aimed to develop comprehensive keys for the identification of described avian Haemoproteus species using morphological features of their blood stages (gametocytes).
METHODS
Type and voucher preparations of avian Haemoproteus species were accessed in museums in Europe, Australia and the USA. Gametocytes of most described species were examined, and these data formed a background for this study. The data also were considered from published articles containing parasite species descriptions. The method of dichotomous keys was applied. The most difficult steps in the keys were accompanied with references to the corresponding parasite pictures.
RESULTS
In all, 201 published articles were included in this review. Morphological diagnostic features of gametocytes of all described Haemoproteus species were analysed and compared. Illustrated keys for identification of these parasite species were developed. Available information about the molecular characterization of Haemoproteus parasites was provided.
CONCLUSION
This review shows that 177 described species of avian Haemoproteus can be distinguished and identified in blood films using morphological characters of their gametocytes and host cells. These species were incorporated in the keys. Information about possible morphologically cryptic parasites was provided. Molecular markers are available for only 42% of the described Haemoproteus parasites, calling for researchers to fill this gap.
Topics: Animals; Birds; Haemosporida; Parasites; Phylogeny; Plasmodium
PubMed: 36123731
DOI: 10.1186/s12936-022-04235-1 -
Canadian Journal of Anaesthesia =... Mar 2015Malaria is a life-threatening infectious disease caused by the Plasmodium parasite. Increased global travel has resulted in an escalation in the number of imported cases... (Review)
Review
PURPOSE
Malaria is a life-threatening infectious disease caused by the Plasmodium parasite. Increased global travel has resulted in an escalation in the number of imported cases seen in developed countries. Patients with malaria may present for surgery in both endemic and non-endemic countries. This article reviews the perioperative considerations when managing patients with malaria.
SOURCE
A literature review of anesthesia, perioperative care, and malaria-related articles was performed using the MEDLINE(®), EMBASE™, and Web of Science databases to identify relevant articles published in English during 1945-2014. Of the 303 articles matching the search criteria, 265 were excluded based on title and abstract. Eleven of the remaining 38 articles were relevant to anesthesia/perioperative care, and 27 articles were identified as having direct relevance to critical care medicine.
PRINCIPAL FINDINGS
The majority of imported malaria cases are caused by the falciparum species, which is associated with the greatest degree of morbidity and mortality. Various organ systems may be impacted as a consequence of changes in the structure and function of parasitized erythrocytes. Preoperative assessment should focus on establishing the species of malaria, the severity of disease, assessing the degree of end-organ impairment, and initiating treatment of malaria prior to surgery. Intravenous artesunate is the treatment of choice for severe falciparum malaria. Quinine is a second-line agent but has a narrow therapeutic index and particularly hazardous side effects. Intraoperatively, attention should focus on fluid management, dynamics of cerebral blood flow, and avoidance of hypoglycemia. Postoperative care of severe cases should ideally take place in a critical care unit as there may be ongoing requirements for multi-organ support, including renal replacement therapy, ventilation, and/or inotropic support. The safety of neuraxial anesthesia has not been well studied in the setting of malaria.
CONCLUSIONS
Malaria remains one of the most devastating infectious diseases worldwide. Multiple organ systems can be impacted as a consequence of changes in structure and function of parasitized erythrocytes. Safe perioperative management requires a sound knowledge of all these potential system effects.
Topics: Antimalarials; Humans; Malaria; Perioperative Care; Plasmodium
PubMed: 25471683
DOI: 10.1007/s12630-014-0286-7 -
Journal of Biosciences 2023Initiation of translation is the first of the three obligatory steps required for protein synthesis and is carried out by a large number of protein factors called...
Initiation of translation is the first of the three obligatory steps required for protein synthesis and is carried out by a large number of protein factors called initiation factors in conjunction with ribosomes. One of the key conserved protein factors in eukaryotes that plays a role in this process is eIF4A, which has three homologues in humans with eIF4A1 being the primary factor playing a role in translation initiation. eIF4As are members of the family of DEAD-box helicases that carry out different biological functions. eIF4A1s are recruited to translation initiation complexes via association with eIF4G and have ATP binding, ATP hydrolysis, RNA binding, and unwinding activities. and trypanosomatids such as and are parasites that cause human disease. While mechanistically the function of eIF4A1s in eukaryotes is wellunderstood, the orthologues peIF4A1s and keIF4A1s in and trypanosomatids are not well-studied. Here, we have used bioinformatics tools and homology modelling/structure prediction to study the motifs and functional signatures of and trypanosomatid peIF4A1s/keIF4A1s. We report a high degree of sequence conservation, structural conservation, and conservation of protein-protein interaction signatures of and trypanosomatid peIF4A1s/keIF4A1s in comparison with human eIF4A1. Thus, in spite of the great divergence in evolution between these parasites and higher eukaryotes, there is remarkable conservation of motifs and functional signatures in and trypanosomatid peIF4A1s/keIF4A1s.
Topics: Humans; Amino Acid Sequence; Protein Binding; Eukaryotic Initiation Factor-4G; Proteins; Eukaryota; Plasmodium; Adenosine Triphosphate
PubMed: 38018538
DOI: No ID Found -
Malaria Journal Nov 2022Indonesia is progressing towards malaria elimination. To achieve this goal, intervention measures must be addressed to cover all Plasmodium species. Comprehensive...
BACKGROUND
Indonesia is progressing towards malaria elimination. To achieve this goal, intervention measures must be addressed to cover all Plasmodium species. Comprehensive control measures and surveillance programmes must be intensified. This study aims to determine the prevalence of microscopic and submicroscopic malaria in Langkat district, North Sumatera Province, Indonesia.
METHODS
A cross-sectional survey was conducted in six villages in Langkat district, North Sumatera Province in June 2019. Data were recorded using a standardized questionnaire. Finger pricked blood samples were obtained for malaria examination using rapid diagnostic test, thick and thin blood smears, and polymerase chain reaction.
RESULTS
A total of 342 individuals were included in the study. Of them, one (0.3%) had a microscopic Plasmodium malariae infection, no positive RDT examination, and three (0.9%) were positive for P. malariae (n = 1) and Plasmodium knowlesi (n = 2). The distribution of bed net ownership was owned by 40% of the study participants. The participants had a house within a radius of 100-500 m from the forest (86.3%) and had the housing material of cement floor (56.1%), a tin roof (82.2%), wooden wall (35.7%), bamboo wall (28.1%), and brick wall (21.6%).
CONCLUSION
Malaria incidence has substantially decreased in Langkat, North Sumatera, Indonesia. However, submicroscopic infection remains in the population and may contribute to further transmission. Surveillance should include the detection of microscopic undetected parasites, to enable the achievement of malaria elimination.
Topics: Humans; Plasmodium knowlesi; Plasmodium malariae; Cross-Sectional Studies; Indonesia; Malaria; Plasmodium falciparum
PubMed: 36333701
DOI: 10.1186/s12936-022-04335-y -
PLoS Pathogens Mar 2023Plasmodium parasites have a complex life cycle alternating between a mosquito and a vertebrate host. Following the bite of an Anopheles female mosquito, Plasmodium... (Review)
Review
Plasmodium parasites have a complex life cycle alternating between a mosquito and a vertebrate host. Following the bite of an Anopheles female mosquito, Plasmodium sporozoites are transmitted from the skin to the liver; their first place of replication within the host. Successfully invaded sporozoites undergo a massive replication and growth involving asynchronous DNA replication and division that results in the generation of tens of thousands or even hundreds of thousands of merozoites depending on the Plasmodium species. The generation of a high number of daughter parasites requires biogenesis and segregation of organelles to finally reach a relatively synchronous cytokinesis event. At the end of liver stage (LS) development, merozoites are packed into merosomes and released into the bloodstream. They are then liberated and infect red blood cells to again produce merozoites by schizogony for the erythrocytic stage of the life cycle. Although parasite LS and asexual blood stage (ABS) differ in many respects, important similarities exist between the two. This review focuses on the cell division of Plasmodium parasite LS in comparison with other life cycle stages especially the parasite blood stage.
Topics: Animals; Cytokinesis; Life Cycle Stages; Liver; Merozoites; Plasmodium; Skin; Sporozoites
PubMed: 36996035
DOI: 10.1371/journal.ppat.1011210 -
MBio Oct 2023Malaria parasites export hundreds of proteins to the cytoplasm of the host red blood cells for their survival. A five amino acid sequence, called the PEXEL motif, is...
Malaria parasites export hundreds of proteins to the cytoplasm of the host red blood cells for their survival. A five amino acid sequence, called the PEXEL motif, is conserved among many exported proteins and is thought to be a signal for export. However, the motif is cleaved inside the endoplasmic reticulum of the parasite, and mature proteins starting from the fourth PEXEL residue travel to the parasite periphery for export. We showed that the PEXEL motif is dispensable for export as long as identical mature proteins can be efficiently produced via alternative means in the ER. We also showed that the exported and non-exported proteins are differentiated at the parasite periphery based on their mature N-termini; however, any discernible export signal within that region remained cryptic. Our study resolves a longstanding paradox in PEXEL protein trafficking.
Topics: Protozoan Proteins; Plasmodium; Protein Transport; Erythrocytes; Endoplasmic Reticulum; Plasmodium falciparum
PubMed: 37646514
DOI: 10.1128/mbio.01215-23 -
Malaria Journal Nov 2016The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has...
BACKGROUND
The Greater Mekong Subregion is aiming to achieve regional malaria elimination by 2030. Though a shift in malaria parasite species predominance by Plasmodium vivax has been recently documented, the transmission of the two minor Plasmodium species, Plasmodium malariae and Plasmodium ovale spp., is poorly characterized in the region. This study aims to determine the prevalence of these minor species in the China-Myanmar border area and their genetic diversity.
METHODS
Epidemiology study was conducted during passive case detection in hospitals and clinics in Myanmar and four counties in China along the China-Myanmar border. Cross-sectional surveys were conducted in villages and camps for internally displaced persons to determine the prevalence of malaria infections. Malaria infections were diagnosed initially by microscopy and later in the laboratory using nested PCR for the SSU rRNA genes. Plasmodium malariae and P. ovale infections were confirmed by sequencing the PCR products. The P. ovale subtypes were determined by sequencing the Pocytb, Pocox1 and Pog3p genes. Parasite populations were evaluated by PCR amplification and sequencing of the MSP-1 genes. Antifolate sensitivity was assessed by sequencing the dhfr-ts and dhps genes from the P. malariae and P. ovale isolates.
RESULTS
Analysis of 2701 blood samples collected from the China-Myanmar border by nested PCR targeting the parasite SSU rRNA genes identified 561 malaria cases, including 161 Plasmodium falciparum, 327 P. vivax, 66 P. falciparum/P. vivax mixed infections, 4 P. malariae and 3 P. ovale spp. P. vivax and P. falciparum accounted for >60 and ~30% of all malaria cases, respectively. In comparison, the prevalence of P. malariae and P. ovale spp. was very low and only made up ~1% of all PCR-positive cases. Nevertheless, these two species were often misidentified as P. vivax infections or completely missed by microscopy even among symptomatic patients. Phylogenetic analysis of the SSU rRNA, Pocytb, Pocox1 and Pog3p genes confirmed that the three P. ovale spp. isolates belonged to the subtype P. ovale curtisi. Low-level genetic diversity was detected in the MSP-1, dhfr and dhps genes of these minor parasite species, potentially stemming from the low prevalence of these parasites preventing their mixing. Whereas most of the dhfr and dhps positions equivalent to those conferring antifolate resistance in P. falciparum and P. vivax were wild type, a new mutation S113C corresponding to the S108 position in pfdhfr was identified in two P. ovale curtisi isolates.
CONCLUSIONS
The four human malaria parasite species all occurred sympatrically at the China-Myanmar border. While P. vivax has become the predominant species, the two minor parasite species also occurred at very low prevalence but were often misidentified or missed by conventional microscopy. These minor parasite species displayed low levels of polymorphisms in the msp-1, dhfr and dhps genes.
Topics: Adult; Child; China; Cluster Analysis; Cross-Sectional Studies; DNA, Protozoan; DNA, Ribosomal; Drug Resistance; Female; Genetic Variation; Humans; Malaria; Male; Microscopy; Myanmar; Phylogeny; Plasmodium falciparum; Plasmodium malariae; Plasmodium ovale; Plasmodium vivax; Polymerase Chain Reaction; Prevalence; Protozoan Proteins; RNA, Ribosomal, 18S; Sequence Analysis, DNA; Young Adult
PubMed: 27846879
DOI: 10.1186/s12936-016-1605-y -
Trends in Parasitology Nov 2020Research on Plasmodium parasites has driven breakthroughs in reducing malaria morbidity and mortality. Experimental analysis of in vivo/ex vivo versus in vitro samples... (Review)
Review
Research on Plasmodium parasites has driven breakthroughs in reducing malaria morbidity and mortality. Experimental analysis of in vivo/ex vivo versus in vitro samples serve unique roles in Plasmodium research. However, these distinctly different environments lead to discordant biology between parasites in host circulation and those under laboratory cultivation. Here, we review how in vitro factors, such as nutrient levels and physical forces, differ from those in the human host and the resulting implications for parasite growth, survival, and virulence. Additionally, we discuss the current utility of direct-from-host methodologies, which avoid the potentially confounding effects of in vitro cultivation. Finally, we make the case for methodological improvements that will drive research progress of physiologically relevant phenotypes.
Topics: Animals; Cells, Cultured; Erythrocytes; Host-Parasite Interactions; Humans; In Vitro Techniques; Malaria; Plasmodium
PubMed: 32958385
DOI: 10.1016/j.pt.2020.08.008 -
Frontiers in Cellular and Infection... 2021Malaria parasites can adjust the proportion of parasites that develop into gametocytes, and thus the probability for human-to-vector transmission, through changes in the... (Review)
Review
Malaria parasites can adjust the proportion of parasites that develop into gametocytes, and thus the probability for human-to-vector transmission, through changes in the gametocyte conversion rate. Understanding the factors that impact the commitment of malaria parasites to transmission is required to design better control interventions. spp. persist across countries with vast differences in transmission intensities, and in sites where transmission is highly seasonal. Mounting evidence shows that spp. adjusts the investment in transmission according to seasonality of vector abundance, and transmission intensity. Various techniques to determine the investment in transmission are available, i.e., short-term culture, where the conversion rate can be measured most directly, genome and transcriptome studies, quantification of mature gametocytes, and mosquito feeding assays. In sites with seasonal transmission, the proportion of gametocytes, their densities and infectivity are higher during the wet season, when vectors are plentiful. When countries with pronounced differences in transmission intensity were compared, the investment in transmission was higher when transmission was low, thus maximizing the parasite's chances to be transmitted to mosquitoes. Increased transmissibility of residual infections after a successful reduction of malaria transmission levels need to be considered when designing intervention measures.
Topics: Animals; Humans; Malaria, Falciparum; Mosquito Vectors; Plasmodium falciparum; Plasmodium vivax; Seasons
PubMed: 34956934
DOI: 10.3389/fcimb.2021.786317 -
Infection and Immunity Jul 2017Malaria vaccine development has been dominated by the subunit approach; however, many subunit vaccine candidates have had limited efficacy in settings of malaria... (Review)
Review
Malaria vaccine development has been dominated by the subunit approach; however, many subunit vaccine candidates have had limited efficacy in settings of malaria endemicity. As our search for an efficacious malaria vaccine continues, the development of a whole-organism vaccine is now receiving much scrutiny. One strategy currently being explored in the development of a whole-organism vaccine involves chemical attenuation of the malaria parasite. and chemical attenuation of both liver-stage and blood-stage parasites has been investigated. Here, we discuss both approaches of chemical attenuation in the development of a whole-organism vaccine against malaria.
Topics: Animals; Antimalarials; Malaria Vaccines; Plasmodium; Vaccines, Attenuated
PubMed: 28438976
DOI: 10.1128/IAI.00062-17