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Current Opinion in Microbiology Aug 2015Plasmodium parasites belong to the Apicomplexan phylum, which consists mostly of obligate intracellular pathogens that vary dramatically in host cell tropism. Plasmodium... (Review)
Review
Plasmodium parasites belong to the Apicomplexan phylum, which consists mostly of obligate intracellular pathogens that vary dramatically in host cell tropism. Plasmodium sporozoites are highly hepatophilic. The specific molecular mechanisms, which facilitate sporozoite selection and successful infection of hepatocytes, remain poorly defined. Here, we discuss the parasite and host factors which are critical to hepatocyte infection. We derive a model where sporozoites initially select host cells that constitute a permissive environment and then further refine the chosen hepatocyte during liver stage development, ensuring life cycle progression. While many unknowns of pre-erythrocytic infection remain, advancing models and technologies that enable analysis of human malaria parasites and of single infected cells will catalyze a comprehensive understanding of the interaction between the malaria parasite and its hepatocyte host.
Topics: Animals; Disease Models, Animal; Hepatocytes; Host-Pathogen Interactions; Humans; Models, Biological; Parasitology; Plasmodium
PubMed: 26102161
DOI: 10.1016/j.mib.2015.05.013 -
Trends in Parasitology May 2015Climate is changing rapidly in the Arctic. This has important implications for parasites of Arctic ungulates, and hence for the welfare of Arctic peoples who depend on... (Review)
Review
Climate is changing rapidly in the Arctic. This has important implications for parasites of Arctic ungulates, and hence for the welfare of Arctic peoples who depend on caribou, reindeer, and muskoxen for food, income, and a focus for cultural activities. In this Opinion article we briefly review recent work on the development of predictive models for the impacts of climate change on helminth parasites and other pathogens of Arctic wildlife, in the hope that such models may eventually allow proactive mitigation and conservation strategies. We describe models that have been developed using the metabolic theory of ecology. The main strength of these models is that they can be easily parameterized using basic information about the physical size of the parasite. Initial results suggest they provide important new insights that are likely to generalize to a range of host-parasite systems.
Topics: Animals; Animals, Wild; Arctic Regions; Climate Change; Host-Parasite Interactions; Humans; Models, Theoretical; Parasites; Parasitic Diseases, Animal
PubMed: 25900882
DOI: 10.1016/j.pt.2015.03.006 -
Frontiers in Cellular and Infection... 2020Extracellular vesicles (EVs) are membranous structures formed during biological processes in living organisms. For protozoan parasites, secretion of EVs can occur... (Review)
Review
Extracellular vesicles (EVs) are membranous structures formed during biological processes in living organisms. For protozoan parasites, secretion of EVs can occur directly from the parasite organellar compartments and through parasite-infected or antigen-stimulated host cells in response to and physiological stressors. These secreted EVs characteristically reflect the biochemical features of their parasitic origin and activating stimuli. Here, we review the species-specific morphology and integrity of parasitic protozoan EVs in concurrence with the origin, functions, and internalization process by recipient cells. The activating stimuli for the secretion of EVs in pathogenic protozoa are discoursed alongside their biomolecules and specific immune cell responses to protozoan parasite-derived EVs. We also present some insights on the intricate functions of EVs in the context of protozoan parasitism.
Topics: Animals; Exosomes; Extracellular Vesicles; Host-Parasite Interactions; Parasites; Protozoan Proteins
PubMed: 32923407
DOI: 10.3389/fcimb.2020.00371 -
Parasitology Dec 2022Given the abundance, heterogeneity and ubiquity of parasitic organisms, understanding how they influence biodiversity, evolution, health and ecosystem functionality is... (Review)
Review
Given the abundance, heterogeneity and ubiquity of parasitic organisms, understanding how they influence biodiversity, evolution, health and ecosystem functionality is crucial, especially currently when anthropogenic pressures are altering host–parasite balances. This review describes the features, roles and impacts of metazoan parasites of fish occurring in transitional waters (TW). These aquatic ecosystems are highly productive and widespread around the globe and represent most favourable theatres for parasitism given the availability of hosts (invertebrates, fishes and birds) and an increased probability of parasite transmission, especially of those having complex life cycles. Fascinating examples of how parasitism can influence different hierarchical levels of biological systems, from host individuals and populations to entire aquatic communities, through effects on food webs come from this kind of ecosystem. Edible fish of commercial value found in TW can harbour some parasite species, significantly reducing host health, marketability and food safety, with possible economic and public health consequences. Many TW are historically exploited by humans as sources of relevant ecosystem services, including fisheries and aquaculture, and they are highly vulnerable ecosystems. Alteration of TW can be revealed through the study of parasite communities, contributing, as bioindicators, for assessing environmental changes, health and restoration. Fish parasites can provide much information about TW, but this potential appears to be not fully exploited. More studies are necessary to quantify the ecological, economic and medical impacts fish parasites can have on these important ecosystems.
Topics: Humans; Animals; Parasites; Ecosystem; Host-Parasite Interactions; Fishes; Fisheries; Fish Diseases
PubMed: 35946119
DOI: 10.1017/S0031182022001068 -
Trends in Parasitology Oct 2015Nucleic acid extraction and sequencing of genes from organisms within environmental samples encompasses a variety of techniques collectively referred to as environmental... (Review)
Review
Nucleic acid extraction and sequencing of genes from organisms within environmental samples encompasses a variety of techniques collectively referred to as environmental DNA or 'eDNA'. The key advantages of eDNA analysis include the detection of cryptic or otherwise elusive organisms, large-scale sampling with fewer biases than specimen-based methods, and generation of data for molecular systematics. These are particularly relevant for parasitology because parasites can be difficult to locate and are morphologically intractable and genetically divergent. However, parasites have rarely been the focus of eDNA studies. Focusing on eukaryote parasites, we review the increasing diversity of the 'eDNA toolbox'. Combining eDNA methods with complementary tools offers much potential to understand parasite communities, disease risk, and parasite roles in broader ecosystem processes such as food web structuring and community assembly.
Topics: Animals; DNA; Ecosystem; Environmental Monitoring; Parasites; Parasitology
PubMed: 26433253
DOI: 10.1016/j.pt.2015.06.013 -
Physiological and Biochemical Zoology :... 2019Tolerance, or the maintenance of host health or fitness at a given parasite burden, has often been studied in evolutionary and medical contexts, particularly with... (Review)
Review
Tolerance, or the maintenance of host health or fitness at a given parasite burden, has often been studied in evolutionary and medical contexts, particularly with respect to effects on the evolution of parasite virulence and individual patient outcomes. These bodies of work have provided insight about tolerance for evolutionary phenomena (e.g., virulence) and individual health (e.g., recovering from an infection). However, due to the specific motivations of that work, few studies have considered the ecological ramifications of variation in tolerance, namely, how variation in forms of tolerance could mediate parasite movement through populations and even community-level disease dynamics. Tolerance is most commonly regarded as the relationship between host fitness and parasite burden. However, few if any studies have actually quantified host fitness, instead utilizing proxies of fitness as the response variables to be regressed against parasite burden. Here, we address how attention to the effects of parasite burden on traits that are relevant to host competence (i.e., the ability to amplify parasites to levels transmissible to other hosts/vectors) will enhance our understanding of disease dynamics in nature. We also provide several forms of guidance for how to overcome the challenges of quantifying tolerance in wild organisms.
Topics: Adaptation, Biological; Animals; Disease Resistance; Host-Parasite Interactions; Parasite Load; Parasites; Parasitic Diseases
PubMed: 30481116
DOI: 10.1086/701169 -
Parasitology Sep 2019New technological methods, such as rapidly developing molecular approaches, often provide new tools for scientific advances. However, these new tools are often not... (Review)
Review
New technological methods, such as rapidly developing molecular approaches, often provide new tools for scientific advances. However, these new tools are often not utilized equally across different research areas, possibly leading to disparities in progress between these areas. Here, we use empirical evidence from the scientific literature to test for potential discrepancies in the use of genetic tools to study parasitic vs non-parasitic organisms across three distinguishable molecular periods, the allozyme, nucleotide and genomics periods. Publications on parasites constitute only a fraction (<5%) of the total research output across all molecular periods and are dominated by medically relevant parasites (especially protists), particularly during the early phase of each period. Our analysis suggests an increasing complexity of topics and research questions being addressed with the development of more sophisticated molecular tools, with the research focus between the periods shifting from predominantly species discovery to broader theory-focused questions. We conclude that both new and older molecular methods offer powerful tools for research on parasites, including their diverse roles in ecosystems and their relevance as human pathogens. While older methods, such as barcoding approaches, will continue to feature in the molecular toolbox of parasitologists for years to come, we encourage parasitologists to be more responsive to new approaches that provide the tools to address broader questions.
Topics: Genetic Techniques; Molecular Biology; Parasitology
PubMed: 31142396
DOI: 10.1017/S0031182019000726 -
The Journal of Animal Ecology Sep 2019Parasitism and competition are both ubiquitous interactions in ecological communities. The ability of host species to interact directly via competition and indirectly... (Review)
Review
Parasitism and competition are both ubiquitous interactions in ecological communities. The ability of host species to interact directly via competition and indirectly through shared parasites suggests that host traits related to competition and parasitism are likely important in structuring communities and disease dynamics. Specifically, those host traits affecting competition and those mediating parasitism are often correlated either because of trade-offs (in resource acquisition or resource allocation) or condition dependence, yet the consequences of these trait relationships for community and epidemiological dynamics are poorly understood. We conducted a literature review of parasite-related host traits-competitive ability relationships. We found that transmission-competitive ability relationships were most often reported, and that superior competitors exhibited elevated transmission relative to their less-competitive counterparts in nearly 80% of the cases. We also found a significant number of virulence-competitive ability and parasite shedding-competitive ability relationships. We investigated these links by altering the relationship between host competitive ability and three parasite-related traits (transmission, virulence and parasite shedding rates) in a simple model, incorporating competitive asymmetries in a multi-host community. We show that these relationships can lead to a range of different communities. For example, depending on the strength and direction of these distinct trait relationships, we observed communities with anywhere from high parasite prevalence to complete parasite extinction, and either one, two or the maximum of three host species coexisting. Our results suggest that parasite-competitive ability relationships may be common in nature, that further integration of these relationships can produce novel and unexpected community and disease dynamics, and that generalizations may allow for the prediction of how parasitism and competition jointly structure disease and diversity in natural communities.
Topics: Animals; Host Specificity; Host-Parasite Interactions; Parasites; Phenotype; Symbiosis; Virulence
PubMed: 31120552
DOI: 10.1111/1365-2656.13028 -
Frontiers in Cellular and Infection... 2023
Topics: Animals; Humans; Systems Biology; Parasitic Diseases; Parasites
PubMed: 37124048
DOI: 10.3389/fcimb.2023.1192732 -
Journal of Helminthology Jan 2023Reptiles, as well as other vertebrate groups, harbour a significant diversity of parasitic organisms, from nematodes and other helminths to viruses and bacteria. The... (Review)
Review
Reptiles, as well as other vertebrate groups, harbour a significant diversity of parasitic organisms, from nematodes and other helminths to viruses and bacteria. The Northeast is one of the richest regions in Brazil in terms of the reptile diversity, number of species and endemism. Parasites are diverse organisms and knowledge about the parasitic fauna of vertebrates is an important factor in understanding the ecological relationships between hosts and the environment. Studies on the parasitic fauna of reptiles in South America have increased in the past few years. The present review is a compilation of 122 studies published from 1924 to 2021. We present information on 101 species of reptiles from five groups (amphisbaenians, crocodile, testudines, snakes and lizards) and 183 parasitic taxa belonging to four phyla: Nematoda; Arthropoda; Platyhelminthes; and Acanthocephala. Nematodes were the most frequently recorded species. Lizards and snakes had more records of parasitism and higher levels of parasite richness and diversity. Ceará was the state with most studies and recorded cases of parasite-host association. The Caatinga and Atlantic Forest were the most investigated environments. The objective of this review was to contribute knowledge on the parasitic biodiversity in reptiles from Northeast Brazil, which may help identify gaps in our knowledge and guide future studies.
Topics: Animals; Parasites; Brazil; Checklist; Nematoda; Lizards; Snakes
PubMed: 36637249
DOI: 10.1017/S0022149X22000785