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PLoS Neglected Tropical Diseases Aug 2018Neglected tropical diseases caused by metazoan parasites are major public health concerns, and therefore, new methods for their control and elimination are needed.... (Review)
Review
Neglected tropical diseases caused by metazoan parasites are major public health concerns, and therefore, new methods for their control and elimination are needed. Research over the last 25 years has revealed the vital contribution of cysteine proteases to invasion of and migration by (larval) helminth parasites through host tissues, in addition to their roles in embryogenesis, molting, egg hatching, and yolk degradation. Their central function to maintaining parasite survival in the host has made them prime intervention targets for novel drugs and vaccines. This review focuses on those helminth cysteine proteases that have been functionally characterized during the varied early stages of development in the human host and embryogenesis.
Topics: Animals; Cysteine Proteases; Cysteine Proteinase Inhibitors; Helminths; Humans; Neglected Diseases; Parasites
PubMed: 30138448
DOI: 10.1371/journal.pntd.0005919 -
Parasites & Vectors Feb 2017Environmental parasitology deals with the interactions between parasites and pollutants in the environment. Their sensitivity to pollutants and environmental... (Review)
Review
Environmental parasitology deals with the interactions between parasites and pollutants in the environment. Their sensitivity to pollutants and environmental disturbances makes many parasite taxa useful indicators of environmental health and anthropogenic impact. Over the last 20 years, three main research directions have been shown to be highly promising and relevant, namely parasites as accumulation indicators for selected pollutants, parasites as effect indicators, and the role of parasites interacting with established bioindicators. The current paper focuses on the potential use of parasites as indicators of environmental pollution and the interactions with their hosts. By reviewing some of the most recent findings in the field of environmental parasitology, we summarize the current state of the art and try to identify promising ideas for future research directions. In detail, we address the suitability of parasites as accumulation indicators and their possible application to demonstrate biological availability of pollutants; the role of parasites as pollutant sinks; the interaction between parasites and biomarkers focusing on combined effects of parasitism and pollution on the health of their hosts; and the use of parasites as indicators of contaminants and ecosystem health. Therefore, this review highlights the application of parasites as indicators at different biological scales, from the organismal to the ecosystem.
Topics: Animals; Environmental Microbiology; Environmental Pollutants; Environmental Pollution; Parasites
PubMed: 28166838
DOI: 10.1186/s13071-017-2001-3 -
PLoS Neglected Tropical Diseases Feb 2014In mammals subverted as hosts by protozoan parasites, the latter and/or the agonists they release are detected and processed by sensors displayed by many distinct immune... (Review)
Review
In mammals subverted as hosts by protozoan parasites, the latter and/or the agonists they release are detected and processed by sensors displayed by many distinct immune cell lineages, in a tissue(s)-dependent context. Focusing on the T lymphocyte lineage, we review our present understanding on its transient or durable functional impairment over the course of the developmental program of the intracellular parasites Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Trypanosoma cruzi in their mammalian hosts. Strategies employed by protozoa to down-regulate T lymphocyte function may act at the initial moment of naïve T cell priming, rendering T cells anergic or unresponsive throughout infection, or later, exhausting T cells due to antigen persistence. Furthermore, by exploiting host feedback mechanisms aimed at maintaining immune homeostasis, parasites can enhance T cell apoptosis. We will discuss how infections with prominent intracellular protozoan parasites lead to a general down-regulation of T cell function through T cell anergy and exhaustion, accompanied by apoptosis, and ultimately allowing pathogen persistence.
Topics: Animals; Host-Parasite Interactions; Humans; Models, Immunological; Parasites; Parasitic Diseases; T-Lymphocytes
PubMed: 24551250
DOI: 10.1371/journal.pntd.0002567 -
Cell Host & Microbe Jul 2010Pathogens interact with their hosts at different spatial and temporal scales. Studying these interactions therefore requires a wide range of imaging tools and approaches... (Review)
Review
Pathogens interact with their hosts at different spatial and temporal scales. Studying these interactions therefore requires a wide range of imaging tools and approaches that bridge physics and biology, as shown by this Minireview focusing on recent studies of the causative agents of malaria, toxoplasmosis, and sleeping sickness.
Topics: Animals; Diagnostic Imaging; Host-Parasite Interactions; Malaria; Parasites; Trypanosomiasis, African
PubMed: 20638638
DOI: 10.1016/j.chom.2010.06.013 -
Parasites & Vectors Sep 2020In more recent years, international travel with cats has increased. The distribution of cat parasites can change with this movement. Already, subtropical and tropical...
BACKGROUND
In more recent years, international travel with cats has increased. The distribution of cat parasites can change with this movement. Already, subtropical and tropical parasites have been reported by veterinarians in areas where they are not naturally present. Understanding the prevalence of tropical and subtropical parasites in Caribbean islands and the risk of importation to temperate areas could enable improved prevention recommendations and border control import requirements.
METHODS
We present a study focused on cat owning students enrolled in a Doctor of Veterinary Medicine (DVM) programme on St Kitts. Owners were interviewed about their cats and their use of parasiticides. Cats were examined for Trichuris felis and Platynosomum fastosum using sugar flotation, Lynxacarus radovskyi using an adhesive tape test, and Dirofilaria immitis using commercial antigen and antibody tests.
RESULTS
Data on 115 cats owned by 87 DVM students were collected and 90 cats, all expected to travel to the USA, were examined. Most of the cats were adults and born in St Kitts. Prevalence was reported as 6.8% (95% confidence interval (CI): 2.2-15.1%) for T. felis, 16.2% (95% CI: 8.7-26.6%) for P. fastosum and 6.8% (95% CI: 2.5-14.3%) for L. radovskyi. All D. immitis tests were negative. DVM students reported a high level of deworming (83.3% of the cats), but the number of cats treated per recommendations were low (56.1% for endoparasites and 70.8% for ectoparasites). Also, there was a lack of clarity regarding the purpose of the treatments used and treatments did not appear to be targeted for the parasites present.
CONCLUSION
Our results indicate a low prevalence of the parasites of interest in the DVM student cat population compared to other prevalence studies from the Caribbean. However, a degree of non-compliance with parasiticide uses and the high number of cats traveling to the USA indicate a medium risk of importation of tropical and subtropical cat parasites to temperate areas. We recommend stronger health inspections and health screening requirements at the borders including the development of specific parasiticide protocols for cat importation.
Topics: Animals; Antiparasitic Agents; Caribbean Region; Cat Diseases; Cats; Feces; Female; Male; Parasites; Parasitic Diseases, Animal; Prevalence; West Indies
PubMed: 32967706
DOI: 10.1186/s13071-020-04365-y -
Genetics Dec 2015Recent and rapid advances in genetic and molecular tools have brought spectacular tractability to Caenorhabditis elegans, a model that was initially prized because of... (Review)
Review
Recent and rapid advances in genetic and molecular tools have brought spectacular tractability to Caenorhabditis elegans, a model that was initially prized because of its simple design and ease of imaging. C. elegans has long been a powerful model in biomedical research, and tools such as RNAi and the CRISPR/Cas9 system allow facile knockdown of genes and genome editing, respectively. These developments have created an additional opportunity to tackle one of the most debilitating burdens on global health and food security: parasitic nematodes. I review how development of nonparasitic nematodes as genetic models informs efforts to import tools into parasitic nematodes. Current tools in three commonly studied parasites (Strongyloides spp., Brugia malayi, and Ascaris suum) are described, as are tools from C. elegans that are ripe for adaptation and the benefits and barriers to doing so. These tools will enable dissection of a huge array of questions that have been all but completely impenetrable to date, allowing investigation into host-parasite and parasite-vector interactions, and the genetic basis of parasitism.
Topics: Animals; Caenorhabditis elegans; Genetic Techniques; Humans; Nematoda; Parasitology
PubMed: 26644478
DOI: 10.1534/genetics.115.182717 -
Diseases of Aquatic Organisms Oct 2019Amphipods are commonly used test organisms in ecotoxicological studies. Nevertheless, their naturally occurring parasites have mostly been neglected in these... (Review)
Review
Amphipods are commonly used test organisms in ecotoxicological studies. Nevertheless, their naturally occurring parasites have mostly been neglected in these investigations, even though several groups of parasites can have a multitude of effects, e.g. on host survival, physiology, or behavior. In the present review, we summarize the knowledge on the effects of Microsporidia and Acanthocephala, 2 common and abundant groups of parasites in amphipods, on the outcome of ecotoxicological studies. Parasites can have significant effects on toxicological endpoints (e.g. mortality, biochemical markers) that are unexpected in some cases (e.g. down-regulation of heat shock protein 70 response in infected individuals). Therefore, parasites can bias the interpretation of results, for example if populations with different parasite profiles are compared, or if toxicological effects are masked by parasite effects. With the present review, we would like to encourage ecotoxicologists to consider parasites as an additional factor if field-collected test organisms are analyzed for biomarkers. Additionally, we suggest intensification of research activities on the effects of parasites in amphipods in connection with other stressors to disentangle parasite and pollution effects and to improve our understanding of parasite effects in this host taxon.
Topics: Acanthocephala; Amphipoda; Animals; Host-Parasite Interactions; Microsporidia; Parasites
PubMed: 31575839
DOI: 10.3354/dao03355 -
Tropical Medicine & International... Jun 2012To review methods for the statistical analysis of parasite and other skewed count data. (Review)
Review
OBJECTIVE
To review methods for the statistical analysis of parasite and other skewed count data.
METHODS
Statistical methods for skewed count data are described and compared, with reference to a 10-year period of Tropical Medicine and International Health (TMIH). Two parasitological datasets are used for illustration.
RESULTS
The review of TMIH found 90 articles, of which 89 used descriptive methods and 60 used inferential analysis. A lack of clarity is noted in identifying the measures of location, in particular the Williams and geometric means. The different measures are compared, emphasising the legitimacy of the arithmetic mean for the skewed data. In the published articles, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasising (1) non-parametric methods, while noting that they are not simply comparisons of medians, and (2) generalised linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described.
CONCLUSIONS
Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalised linear models are likely to be sufficient for most analyses.
Topics: Animals; Humans; Linear Models; Parasite Load; Parasites; Parasitology; Research Design
PubMed: 22943299
DOI: 10.1111/j.1365-3156.2012.02987.x -
Parasite (Paris, France) Sep 2008Parasite requires an understanding of complex transmission systems where individual, population and environmental factors and their interactions can hardly been... (Review)
Review
Parasite requires an understanding of complex transmission systems where individual, population and environmental factors and their interactions can hardly been considered separately. Moreover, the importance of space and time in host population and parasite transmission processes is increasingly recognised. The present review illustrates how epidemiology and transmission ecology have evolved in a multidisciplinary framework to a systems approach that includes both spatial and temporal dimensions. Focusing on population processes, three significant challenges are discussed: (i) integration of landscape ecology concepts and modelling across time-space scales, (ii) development of molecular methods that permits easy parasite/host identification and process tracking (e.g. host and parasite movements), and (iii) integration of sociology methods to estimate zoonotic risk and exposure.
Topics: Animals; Demography; Ecosystem; Host-Parasite Interactions; Humans; Parasites; Parasitic Diseases; Parasitology; Risk Assessment; Sentinel Surveillance; Space-Time Clustering; Species Specificity
PubMed: 18814725
DOI: 10.1051/parasite/2008153469 -
International Journal For Parasitology May 2023Parasitic helminths exhibit remarkable diversity in their life cycles, although few parasite species have their whole life cycles resolved. Owing to the fact that...
Parasitic helminths exhibit remarkable diversity in their life cycles, although few parasite species have their whole life cycles resolved. Owing to the fact that parasite life stages within hosts are often not comparable using morphological data, genetic data provides convincing evidence of transmission pathways between intermediate and definitive hosts. We took this approach to an ecosystem level, genetically matching parasite (acanthocephalan, cestode, nematode and trematode) life stages across a broad taxonomic range of intermediate and definitive hosts (invertebrates, seabirds, elasmobranchs and teleost fish) in Otago's (New Zealand) coastal marine ecosystem. We identified which transmission routes are utilized by the most parasite species and assessed which intermediate hosts are most important in facilitating the transmission of parasites in this ecosystem. Our findings reveal 59 new records of larval parasites infecting their respective intermediate hosts and 289 transmission pathways utilized by 35 helminth species to complete their life cycles. Sprat, triplefin and arrow squid all hosted the highest number of larval parasite species, suggesting they play important roles as intermediate hosts. We then used the new life cycle data to provide a synthetic overview of the life cycles known for various parasite groups in New Zealand. This study highlights how studying parasite life cycles can enhance our understanding of the ecology and evolution of parasites and hosts in natural systems, beyond simply resolving life cycles.
Topics: Animals; Parasites; Ecosystem; Life Cycle Stages; Helminths; Ecology; Fishes; Larva; Host-Parasite Interactions
PubMed: 37001631
DOI: 10.1016/j.ijpara.2023.02.004