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Trends in Parasitology Dec 2019Trait-based research holds high potential to unveil ecological and evolutionary processes. Functional traits are fitness-related characteristics of individuals, which... (Review)
Review
Trait-based research holds high potential to unveil ecological and evolutionary processes. Functional traits are fitness-related characteristics of individuals, which are measured at individual level and defined without using information external to the individual. Despite the usefulness of the functional approach to understand the performance of individuals in ecosystems, and parasitism being the most common life-history strategy on Earth, studies based on functional traits of parasites are still scarce. Since the choice of functional traits is a critical step for any study, we propose a core list of seven functional traits of metazoan parasites, related to three universal challenges faced by organisms (dispersal, establishment, and persistence), and give guidelines to define appropriate functional traits in future parasite community studies.
Topics: Animals; Ecosystem; Host-Parasite Interactions; Life Cycle Stages; Life History Traits; Models, Biological; Parasites; Parasitology
PubMed: 31678065
DOI: 10.1016/j.pt.2019.09.003 -
The Pediatric Infectious Disease Journal Jun 2019Human stool contains a myriad of microorganisms, of which the vast majority are nonpathogenic and represent an important component of the healthy microbiome. The... (Review)
Review
Human stool contains a myriad of microorganisms, of which the vast majority are nonpathogenic and represent an important component of the healthy microbiome. The increasing use of molecular techniques has allowed the rapid identification of bacteria, viruses and parasites in human stool. This review focuses on the 3 main classes of parasite responsible for human disease, helminths, protozoa and ectoparasites, and highlights the importance of differentiating between pathogenic and nonpathogenic parasites.
Topics: Animals; Child; Ectoparasitic Infestations; Feces; Gastrointestinal Diseases; Helminthiasis; Humans; Parasites; Parasitic Diseases; Protozoan Infections
PubMed: 31205245
DOI: 10.1097/INF.0000000000002323 -
Seminars in Cell & Developmental Biology Oct 2015A huge variety of protists rely on one or more motile flagella to either move themselves or move fluids and substances around them. Many of these flagellates have... (Review)
Review
A huge variety of protists rely on one or more motile flagella to either move themselves or move fluids and substances around them. Many of these flagellates have evolved a symbiotic or parasitic lifestyle. Several of the parasites have adapted to human hosts, and include agents of prevalent and serious diseases. These unicellular parasites have become specialised in colonising a wide range of biological niches within humans. They usually have diverse transmission cycles, and frequently manifest a variety of distinct morphological stages. The motility of the single or multiple flagella plays important but understudied roles in parasite transmission, host invasion, dispersal, survival, proliferation and pathology. In this review we provide an overview of the important human pathogens that possess a motile flagellum for at least part of their life cycle. We highlight recently published studies that aim to elucidate motility mechanisms, and their relevance for human disease. We then bring the physics of swimming at the microscale into context, emphasising the importance of interdisciplinary approaches for a full understanding of flagellate motility - especially in light of the parasites' microenvironments and population dynamics. Finally, we summarise some important technological aspects, describing challenges for the field and possibilities for motility analyses in the future.
Topics: Animals; Flagella; Host-Parasite Interactions; Humans; Kinetoplastida; Movement; Parasites; Parasitic Diseases; Phylogeny; Plasmodium
PubMed: 26523344
DOI: 10.1016/j.semcdb.2015.10.034 -
Parasitology Feb 2015The genomes of more than 20 helminths have now been sequenced. Here we perform a meta-analysis of all sequenced genomes of nematodes and Platyhelminthes, and attempt to... (Meta-Analysis)
Meta-Analysis Review
The genomes of more than 20 helminths have now been sequenced. Here we perform a meta-analysis of all sequenced genomes of nematodes and Platyhelminthes, and attempt to address the question of what are the defining characteristics of helminth genomes. We find that parasitic worms lack systems for surface antigenic variation, instead maintaining infections using their surfaces as the first line of defence against the host immune system, with several expanded gene families of genes associated with the surface and tegument. Parasite excretory/secretory products evolve rapidly, and proteases even more so, with each parasite exhibiting unique modifications of its protease repertoire. Endoparasitic flatworms show striking losses of metabolic capabilities, not matched by nematodes. All helminths do however exhibit an overall reduction in auxiliary metabolism (biogenesis of co-factors and vitamins). Overall, the prevailing pattern is that there are few commonalities between the genomes of independently evolved parasitic worms, with each parasite having undergone specific adaptations for their particular niche.
Topics: Adaptation, Physiological; Animals; Biological Evolution; Genome, Helminth; Helminths; Immune System; Nematoda; Parasites; Platyhelminths; Transcriptome
PubMed: 25482650
DOI: 10.1017/S0031182014001449 -
Trends in Parasitology Jun 2022γ-aminobutyric acid (GABA) is a nonstructural amino acid that serves diverse functions in unicellular and multicellular organisms. Besides its widely established role... (Review)
Review
γ-aminobutyric acid (GABA) is a nonstructural amino acid that serves diverse functions in unicellular and multicellular organisms. Besides its widely established role in mammals as an inhibitory neurotransmitter, the diverse biological roles and metabolism of GABA in protozoan parasites have begun to be unveiled. GABA acts as either the intracellular signal or cell-to-cell messenger to mediate a variety of cellular responses that protect the parasites from environmental and host-derived stress. Moreover, GABA metabolism was found to be tightly regulated, involving protein machinery confined to the protozoa lineage. Meanwhile, host-parasite GABAergic interaction plays a role in the pathogenesis and disease manifestation of protozoan infections. Therefore, the GABAergic system apparently is broadly involved in essential biological and pathophysiological processes and is well conserved in parasitic and free-living protozoa.
Topics: Animals; Host-Parasite Interactions; Mammals; Parasites; Protozoan Infections; gamma-Aminobutyric Acid
PubMed: 35264298
DOI: 10.1016/j.pt.2022.02.004 -
Frontiers in Immunology 2020
Topics: Animals; Host-Parasite Interactions; Humans; Infection Control; Infections; Parasites
PubMed: 32457761
DOI: 10.3389/fimmu.2020.00880 -
Journal of Clinical Microbiology Nov 2022Advances in laboratory techniques have revolutionized parasitology diagnostics over the past several decades. Widespread implementation of rapid antigen detection tests...
Advances in laboratory techniques have revolutionized parasitology diagnostics over the past several decades. Widespread implementation of rapid antigen detection tests has greatly expanded access to tests for global parasitic threats such as malaria, while next-generation amplification and sequencing methods allow for sensitive and specific detection of human and animal parasites in complex specimen matrices. Recently, the introduction of multiplex panels for human gastrointestinal infections has enhanced the identification of common intestinal protozoa in feces along with bacterial and viral pathogens. Despite the benefits provided by novel diagnostics, increased reliance on nonmicroscopy-based methods has contributed to the progressive, widespread loss of morphology expertise for parasite identification. Loss of microscopy and morphology skills has the potential to negatively impact patient care, public health, and epidemiology. Molecular- and antigen-based diagnostics are not available for all parasites and may not be suitable for all specimen types and clinical settings. Furthermore, inadequate morphology experience may lead to missed and inaccurate diagnoses and erroneous descriptions of new human parasitic diseases. This commentary highlights the need to maintain expert microscopy and morphological parasitology diagnostic skills within the medical and scientific community. We proposed that light microscopy remains an important part of training and practice in the diagnosis of parasitic diseases and that efforts should be made to train the next generation of morphological parasitologists before the requisite knowledge, skills, and capacity for this complex and important mode of diagnosis are lost. In summary, the widespread, progressive loss of morphology expertise for parasite identification negatively impacts patient care, public health, and epidemiology.
Topics: Animals; Humans; Parasitic Diseases; Parasites; Microscopy; Feces; Bacteria
PubMed: 36314793
DOI: 10.1128/jcm.00986-22 -
Integrative and Comparative Biology Oct 2016It is increasingly evident that cryptic stages of many parasites cause asymptomatic infections in a diversity of hosts. This review examines what may cause these... (Review)
Review
It is increasingly evident that cryptic stages of many parasites cause asymptomatic infections in a diversity of hosts. This review examines what may cause these infectious agents to persist as asymptomatic infections in invertebrates and how environmental change is linked with the subsequent development of overt infection and disease. In many systems, disease dynamics are closely associated with host condition which, in turn, is linked with environmental change. Symbionts (commensals and mutualists) display similar dynamics when environmental change causes them to exert negative effects on their hosts. Although such asymptomatic infections are demonstrated in a range of invertebrate hosts they are greatly undersampled because most invertebrate diseases are uninvestigated, infections are difficult to detect, and many parasite groups are poorly characterized. A better understanding of the diversity and distribution of parasites that cause asymptomatic infections and of their complex relationships with invertebrate hosts will enable a fuller appreciation of context-dependent host-parasite interactions and will address the biased focus on diseases of invertebrates of practical importance. The existence of such infections could underlie novel disease outbreaks that might otherwise be attributed to invasives while altered disease dynamics may provide an additional and complementary indicator of ecosystem change.
Topics: Animals; Ecosystem; Host-Parasite Interactions; Invertebrates; Parasites
PubMed: 27085077
DOI: 10.1093/icb/icw008 -
Trends in Parasitology Apr 2016Plasmin is the final product of the fibrinolytic system, the physiological mechanism responsible for dissolving fibrin clots. Its broad-range proteolytic activity... (Review)
Review
Plasmin is the final product of the fibrinolytic system, the physiological mechanism responsible for dissolving fibrin clots. Its broad-range proteolytic activity implies that interaction with fibrinolysis and recruitment of plasmin by blood and tissue parasites is an important mechanism that mediates the invasion and establishment of this kind of pathogen in the hosts. However, recent studies have linked an excess of plasmin generated by this interaction with serious pathological events at the vascular level, including the proliferation and migration of arterial wall cells, inflammation, and degradation of the extracellular matrix. Therefore, we present data that support the need to reconsider the role of plasmin, as well as its benefits or drawbacks, in the context of host-parasite relations.
Topics: Animals; Chronic Disease; Fibrinolysin; Fibrinolysis; Host-Parasite Interactions; Humans; Parasites; Parasitic Diseases
PubMed: 26775037
DOI: 10.1016/j.pt.2015.12.012 -
Trends in Parasitology Aug 2020Reptiles are reservoirs of a wide range of pathogens, including many protozoa, helminths, pentastomids, and arthropod parasitic species, some of which may be of public... (Review)
Review
Reptiles are reservoirs of a wide range of pathogens, including many protozoa, helminths, pentastomids, and arthropod parasitic species, some of which may be of public health concern. In this review we discuss the zoonotic risks associated with human-reptile interactions. Increased urbanization and introduction of exotic species of reptile may act as drivers for the transmission of zoonotic parasites through the environment. In addition, being a part of human diet, reptiles can be a source of life-threatening parasitoses, such as pentastomiasis or sparganosis. Finally, reptiles kept as pets may represent a risk to owners given the possibility of parasites transmitted by direct contact or fecal contamination. Awareness of reptile-borne zoonotic parasitoses is important to advocate control, prevention, and surveillance of these neglected diseases.
Topics: Animals; Food Parasitology; Humans; Parasites; Parasitic Diseases; Pets; Reptiles; Zoonoses
PubMed: 32448703
DOI: 10.1016/j.pt.2020.04.014