-
Annual Review of Marine Science Jan 2021Climate change affects ecological processes and interactions, including parasitism. Because parasites are natural components of ecological systems, as well as agents of... (Review)
Review
Climate change affects ecological processes and interactions, including parasitism. Because parasites are natural components of ecological systems, as well as agents of outbreak and disease-induced mortality, it is important to summarize current knowledge of the sensitivity of parasites to climate and identify how to better predict their responses to it. This need is particularly great in marine systems, where the responses of parasites to climate variables are less well studied than those in other biomes. As examples of climate's influence on parasitism increase, they enable generalizations of expected responses as well as insight into useful study approaches, such as thermal performance curves that compare the vital rates of hosts and parasites when exposed to several temperatures across a gradient. For parasites not killed by rising temperatures, some simple physiological rules, including the tendency of temperature to increase the metabolism of ectotherms and increase oxygen stress on hosts, suggest that parasites' intensity and pathologies might increase. In addition to temperature, climate-induced changes in dissolved oxygen, ocean acidity, salinity, and host and parasite distributions also affect parasitism and disease, but these factors are much less studied. Finally, because parasites are constituents of ecological communities, we must consider indirect and secondary effects stemming from climate-induced changes in host-parasite interactions, which may not be evident if these interactions are studied in isolation.
Topics: Animals; Aquatic Organisms; Climate Change; Ecosystem; Host-Parasite Interactions; Parasites; Parasitic Diseases; Temperature
PubMed: 32520636
DOI: 10.1146/annurev-marine-031920-100429 -
Clinical Microbiology and Infection :... Jun 2015Following the success of nucleic acid-based detection in virology and bacteriology, multiplex real-time PCRs are increasingly used as first-line diagnostics in clinical... (Review)
Review
Following the success of nucleic acid-based detection in virology and bacteriology, multiplex real-time PCRs are increasingly used as first-line diagnostics in clinical parasitology, replacing microscopy. The detection and quantification of parasite-specific DNA in faeces is highly sensitive and specific and allows for cost-effective high-throughput screening. In this paper we discuss the clinical consequences of this radical change in diagnostic approach, as well as its potential drawbacks. In the Netherlands, routine diagnostic laboratories have been pioneering the implementation of multiplex real-time PCR for the detection of pathogenic intestinal protozoa and this has resulted in increased detection rates of Giardia lamblia and Cryptosporidium spp. As a consequence of this new diagnostic approach, expertise in the field of parasite morphology by conventional light microscopy seems to be disappearing in most of the high-throughput microbiological laboratories. As a result, to maintain a high standard of care, a formalized exchange of critical information between clinicians and laboratory staff is necessary to determine the most appropriate testing either in local laboratories or in reference centres, based on clinical signs and symptoms, exposure and immune status. If such a diagnostic algorithm is lacking, important infections in travellers, immigrants and immunocompromised patients may be missed.
Topics: Animals; Clinical Laboratory Techniques; Emigration and Immigration; Humans; Intestinal Diseases, Parasitic; Molecular Diagnostic Techniques; Multiplex Polymerase Chain Reaction; Netherlands; Parasitology; Real-Time Polymerase Chain Reaction
PubMed: 25843505
DOI: 10.1016/j.cmi.2015.03.015 -
Infection and Immunity Aug 2017Parasitic protozoan infections represent a major health burden in the developing world and contribute significantly to morbidity and mortality. These infections are... (Review)
Review
Parasitic protozoan infections represent a major health burden in the developing world and contribute significantly to morbidity and mortality. These infections are often associated with considerable variability in clinical presentation. An emerging body of work suggests that the intestinal microbiota may help to explain some of these differences in disease expression. The objective of this minireview is to synthesize recent progress in this rapidly advancing field. Studies of humans and animals and studies of the contribution of the intestinal microbiota to infectious disease are discussed. We hope to provide an understanding of the human-protozoal pathogen-microbiome interaction and to speculate on how that might be leveraged for treatment.
Topics: Animals; Gastrointestinal Microbiome; Host-Parasite Interactions; Humans; Parasites; Protozoan Infections
PubMed: 28584161
DOI: 10.1128/IAI.00101-17 -
Trends in Parasitology Apr 2015The field of parasitology contributes to the elucidation of patterns and processes in evolution, ecology, and biogeography that are of fundamental importance across the... (Review)
Review
The field of parasitology contributes to the elucidation of patterns and processes in evolution, ecology, and biogeography that are of fundamental importance across the biosphere, leading to a thorough understanding of biodiversity and varied responses to global change. Foundations from taxonomic and systematic information drive biodiversity discovery and foster considerable infrastructure and integration of research programs. Morphological, physiological, behavioral, life-history, and molecular data can be synthesized to discover and describe global parasite diversity, in a timely manner. In fully incorporating parasitology in policies for adaptation to global change, parasites and their hosts should be archived and studied within a newly emergent conceptual universe (the 'Stockholm Paradigm'), embracing the inherent complexity of host-parasite systems and improved explanatory power to understand biodiversity past, present, and future.
Topics: Animals; Biodiversity; Classification; Climate Change; Humans; Parasitology
PubMed: 25488772
DOI: 10.1016/j.pt.2014.11.005 -
Frontiers in Cellular and Infection... 2021For the establishment of a successful infection, , long-term parasitism and a complete life cycle, parasites use various diverse mechanisms and factors, which they may... (Review)
Review
For the establishment of a successful infection, , long-term parasitism and a complete life cycle, parasites use various diverse mechanisms and factors, which they may be inherently bestowed with, or may acquire from the natural vector biting the host at the infection prelude, or may take over from the infecting host, to outmaneuver, evade, overcome, and/or suppress the host immunity, both innately and adaptively. This narrative review summarizes the up-to-date strategies exploited by a number of representative human parasites (protozoa and helminths) to counteract the target host immune defense. The revisited information should be useful for designing diagnostics and therapeutics as well as vaccines against the respective parasitic infections.
Topics: Animals; Helminths; Host-Parasite Interactions; Humans; Immune Evasion; Parasites; Parasitic Diseases
PubMed: 34395313
DOI: 10.3389/fcimb.2021.702125 -
Journal of Clinical Microbiology Jan 2017Parasites of medical importance have long been classified taxonomically by morphological characteristics. However, molecular-based techniques have been increasingly used... (Review)
Review
Parasites of medical importance have long been classified taxonomically by morphological characteristics. However, molecular-based techniques have been increasingly used and relied on to determine evolutionary distances for the basis of rational hierarchal classifications. This has resulted in several different classification schemes for parasites and changes in parasite taxonomy. The purpose of this Minireview is to provide a single reference for diagnostic laboratories that summarizes new and revised clinically relevant parasite taxonomy from January 2012 through December 2015.
Topics: Animals; Classification; Humans; Parasites; Parasitic Diseases; Parasitology
PubMed: 27440818
DOI: 10.1128/JCM.01020-16 -
Journal of Clinical Microbiology Feb 2019Parasite taxonomy continues to change as molecular and morphologic studies enhance our understanding of parasite relatedness. This minireview builds on the information...
Parasite taxonomy continues to change as molecular and morphologic studies enhance our understanding of parasite relatedness. This minireview builds on the information provided in the last taxonomy update in this journal to summarize new and revised clinically relevant human parasite taxonomic changes that have occurred in 2016 and 2017.
Topics: Animals; Humans; Parasites; Parasitic Diseases; Parasitology
PubMed: 30282786
DOI: 10.1128/JCM.01067-18 -
Biological Reviews of the Cambridge... Nov 2018Understanding the coevolution of hosts and parasites is a long-standing goal of evolutionary biology. There is a well-developed theoretical framework to describe the... (Review)
Review
Understanding the coevolution of hosts and parasites is a long-standing goal of evolutionary biology. There is a well-developed theoretical framework to describe the evolution of host-parasite interactions under the assumption of direct, two-species interactions, which can result in arms race dynamics or sustained genotype fluctuations driven by negative frequency dependence (Red Queen dynamics). However, many hosts rely on symbionts for defence against parasites. Whilst the ubiquity of defensive symbionts and their potential importance for disease control are increasingly recognized, there is still a gap in our understanding of how symbionts mediate or possibly take part in host-parasite coevolution. Herein we address this question by synthesizing information already available from theoretical and empirical studies. First, we briefly introduce current hypotheses on how defensive mutualisms evolved from more parasitic relationships and highlight exciting new experimental evidence showing that this can occur very rapidly. We go on to show that defensive symbionts influence virtually all important determinants of coevolutionary dynamics, namely the variation in host resistance available to selection by parasites, the specificity of host resistance, and the trade-off structure between host resistance and other components of fitness. In light of these findings, we turn to the limited theory and experiments available for such three-species interactions to assess the role of defensive symbionts in host-parasite coevolution. Specifically, we discuss under which conditions the defensive symbiont may take over from the host the reciprocal adaptation with parasites and undergo its own selection dynamics, thereby altering or relaxing selection on the hosts' own immune defences. Finally, we address potential effects of defensive symbionts on the evolution of parasite virulence. This is an important problem for which there is no single, clear-cut prediction. The selection on parasite virulence resulting from the presence of defensive symbionts in their hosts will depend on the underlying mechanism of defence. We identify the evolutionary predictions for different functional categories of symbiont-conferred resistance and we evaluate the empirical literature for supporting evidence. We end this review with outstanding questions and promising avenues for future research to improve our understanding of symbiont-mediated coevolution between hosts and parasites.
Topics: Adaptation, Physiological; Animals; Bacteria; Biological Coevolution; Host-Parasite Interactions; Parasites; Symbiosis
PubMed: 29663622
DOI: 10.1111/brv.12417 -
Biomolecules Apr 2020Studies on the parasite-host interaction may provide valuable information concerning the modulation of molecular mechanisms as well as of the host immune system during... (Review)
Review
Studies on the parasite-host interaction may provide valuable information concerning the modulation of molecular mechanisms as well as of the host immune system during infection. To date, it has been demonstrated that intestinal parasites may affect, among others, the processes of digestion in the gastrointestinal system of the host, thus limiting the elimination of the parasite, the immune response as well as inflammation. However, the most recent studies suggest that intestinal parasites may also affect modulation of the apoptosis pathway of the host. The present paper presents the latest scientific information on the influence of intestinal parasite species ( sp., sp., sp., sp., , , ) on the molecular mechanisms of apoptosis in intestinal epithelial cells. This paper stresses that the interdependency between the intestinal parasite and the host results from the direct effect of the parasite and the host's defense reactions, which lead to modulation of the apoptosis pathways (intrinsic and extrinsic). Moreover, the present paper presents the role of proteins involved in the mechanisms of apoptosis as well as the physiological role of apoptosis in the host's intestinal epithelial cells.
Topics: Animals; Apoptosis; Enterocytes; Host-Parasite Interactions; Humans; Intestinal Diseases, Parasitic; Parasites
PubMed: 32349424
DOI: 10.3390/biom10050674 -
Cell Host & Microbe May 2016Protozoan parasites colonize numerous metazoan hosts and insect vectors through their life cycles, with the need to respond quickly and reversibly while encountering... (Review)
Review
Protozoan parasites colonize numerous metazoan hosts and insect vectors through their life cycles, with the need to respond quickly and reversibly while encountering diverse and often hostile ecological niches. To succeed, parasites must also persist within individuals until transmission between hosts is achieved. Several parasitic protozoa cause a huge burden of disease in humans and livestock, and here we focus on the parasites that cause malaria and African trypanosomiasis. Efforts to understand how these pathogens adapt to survive in varied host environments, cause disease, and transmit between hosts have revealed a wealth of epigenetic phenomena. Epigenetic switching mechanisms appear to be ideally suited for the regulation of clonal antigenic variation underlying successful parasitism. We review the molecular players and complex mechanistic layers that mediate the epigenetic regulation of virulence gene expression. Understanding epigenetic processes will aid the development of antiparasitic therapeutics.
Topics: Animals; Gene Expression Regulation; Humans; Parasites; Virulence
PubMed: 27173931
DOI: 10.1016/j.chom.2016.04.020