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Current Biology : CB Sep 2011Parasites and parasitism is common. Worm macroparasites have evolved life-history traits that allow them to successfully transmit between spatially and temporally... (Review)
Review
Parasites and parasitism is common. Worm macroparasites have evolved life-history traits that allow them to successfully transmit between spatially and temporally separated patches of host resource and to survive within these environments. Macroparasites have common life-history strategies to achieve this, but these general themes are modified in a myriad of ways related to the specific biology of their hosts. Parasite life histories are also dynamic, responding to conditions inside and outside of hosts, and they continue to evolve, especially in response to our attempts to control them and the harm that they cause.
Topics: Adaptation, Physiological; Animals; Biological Evolution; Host-Parasite Interactions; Life Cycle Stages; Nematoda; Parasites; Platyhelminths; Reproduction
PubMed: 21959167
DOI: 10.1016/j.cub.2011.07.023 -
American Journal of Botany Jan 2021All organisms engage in parasitic relations, as either parasites or hosts. Some species may even play both roles simultaneously. Among flowering plants, the most... (Review)
Review
All organisms engage in parasitic relations, as either parasites or hosts. Some species may even play both roles simultaneously. Among flowering plants, the most widespread form of parasitism is characterized by the development of an intrusive organ called the haustorium, which absorbs water and nutrients from the host. Despite this functionally unifying feature of parasitic plants, haustoria are not homologous structures; they have evolved 12 times independently. These plants represent ca. 1% of all extant flowering species and show a wide diversity of life histories. A great variety of plants may also serve as hosts, including other parasitic plants. This phenomenon of parasitic exploitation of another parasite, broadly known as hyper- or epiparasitism, is well described among bacteria, fungi, and animals, but remains poorly understood among plants. Here, we review empirical evidence of plant hyperparasitism, including variations of self-parasitism, discuss the diversity and ecological importance of these interactions, and suggest possible evolutionary mechanisms. Hyperparasitism may provide benefits in terms of improved nutrition and enhanced host-parasite compatibility if partners are related. Different forms of self-parasitism may facilitate nutrient sharing among and within parasitic plant individuals, while also offering potential for the evolution of hyperparasitism. Cases of hyperparasitic interactions between parasitic plants may affect the ecology of individual species and modulate their ecosystem impacts. Parasitic plant phenology and disperser feeding behavior are considered to play a major role in the occurrence of hyperparasitism, especially among mistletoes. There is also potential for hyperparasites to act as biological control agents of invasive primary parasitic host species.
Topics: Animals; Ecosystem; Host-Parasite Interactions; Magnoliopsida; Orobanchaceae; Parasites; Plants
PubMed: 33403666
DOI: 10.1002/ajb2.1590 -
Molecular Biology and Evolution May 2021The transition of free-living organisms to parasitic organisms is a mysterious process that occurs in all major eukaryotic lineages. Parasites display seemingly unique... (Comparative Study)
Comparative Study
The transition of free-living organisms to parasitic organisms is a mysterious process that occurs in all major eukaryotic lineages. Parasites display seemingly unique features associated with their pathogenicity; however, it is important to distinguish ancestral preconditions to parasitism from truly new parasite-specific functions. Here, we sequenced the genome and transcriptome of anaerobic free-living Mastigamoeba balamuthi and performed phylogenomic analysis of four related members of the Archamoebae, including Entamoeba histolytica, an important intestinal pathogen of humans. We aimed to trace gene histories throughout the adaptation of the aerobic ancestor of Archamoebae to anaerobiosis and throughout the transition from a free-living to a parasitic lifestyle. These events were associated with massive gene losses that, in parasitic lineages, resulted in a reduction in structural features, complete losses of some metabolic pathways, and a reduction in metabolic complexity. By reconstructing the features of the common ancestor of Archamoebae, we estimated preconditions for the evolution of parasitism in this lineage. The ancestor could apparently form chitinous cysts, possessed proteolytic enzyme machinery, compartmentalized the sulfate activation pathway in mitochondrion-related organelles, and possessed the components for anaerobic energy metabolism. After the split of Entamoebidae, this lineage gained genes encoding surface membrane proteins that are involved in host-parasite interactions. In contrast, gene gains identified in the M. balamuthi lineage were predominantly associated with polysaccharide catabolic processes. A phylogenetic analysis of acquired genes suggested an essential role of lateral gene transfer in parasite evolution (Entamoeba) and in adaptation to anaerobic aquatic sediments (Mastigamoeba).
Topics: Adaptation, Biological; Anaerobiosis; Animals; Archamoebae; Biological Evolution; Entamoeba histolytica; Gene Transfer, Horizontal; Genome Size; Genome, Protozoan; Parasites; Transcriptome
PubMed: 33528570
DOI: 10.1093/molbev/msab020 -
Clinical Microbiology Reviews Jul 2017In the last 2 decades, renewed attention to neglected tropical diseases (NTDs) has spurred the development of antiparasitic agents, especially in light of emerging drug... (Review)
Review
In the last 2 decades, renewed attention to neglected tropical diseases (NTDs) has spurred the development of antiparasitic agents, especially in light of emerging drug resistance. The need for new drugs has required screening methods using parasite culture. Furthermore, clinical laboratories sought to correlate susceptibility methods with treatment outcomes, most notably with malaria. Parasites with their various life cycles present greater complexity than bacteria, for which standardized susceptibility methods exist. This review catalogs the state-of-the-art methodologies used to evaluate the effects of drugs on key human parasites from the point of view of drug discovery as well as the need for laboratory methods that correlate with clinical outcomes.
Topics: Animals; Antiparasitic Agents; Drug Discovery; Humans; Neglected Diseases; Parasites
PubMed: 28446445
DOI: 10.1128/CMR.00111-16 -
Biomolecules Oct 2022The complement system exerts crucial functions both in innate immune responses and adaptive humoral immunity. This pivotal system plays a major role dealing with... (Review)
Review
The complement system exerts crucial functions both in innate immune responses and adaptive humoral immunity. This pivotal system plays a major role dealing with pathogen invasions including protozoan parasites. Different pathogens including parasites have developed sophisticated strategies to defend themselves against complement killing. Some of these strategies include the employment, mimicking or inhibition of host's complement regulatory proteins, leading to complement evasion. Therefore, parasites are proven to use the manipulation of the complement system to assist them during infection and persistence. Herein, we attempt to study the interaction´s mechanisms of some prominent infectious protozoan parasites including , , , and dealing with the complement system. Moreover, several crucial proteins that are expressed, recruited or hijacked by parasites and are involved in the modulation of the host´s complement system are selected and their role for efficient complement killing or lysis evasion is discussed. In addition, parasite's complement regulatory proteins appear as plausible therapeutic and vaccine targets in protozoan parasitic infections. Accordingly, we also suggest some perspectives and insights useful in guiding future investigations.
Topics: Animals; Parasites; Leishmania; Trypanosoma; Plasmodium; Complement System Proteins; Protozoan Infections
PubMed: 36358913
DOI: 10.3390/biom12111564 -
Turkiye Parazitolojii Dergisi Dec 2020Ocular parasitic infections, which lead to significant morbidity and mortality in particular areas, have been shifting from endemic areas to other regions due to... (Review)
Review
Ocular parasitic infections, which lead to significant morbidity and mortality in particular areas, have been shifting from endemic areas to other regions due to tourism, wars and migrations in recent years. This study aimed to review the parasitic factors related to the human eye and their geographical distribution, pathogenesis of the disease and the methods used in and studies conducted for its diagnosis. PubMed, MEDLINE and Google databases were researched and reviewed for relevant keywords in recent publications. Although such parasitic infections are rare in many parts of the world, they continue to be an important public health problem that affects human and animal health in places with poor health conditions. The distribution of ocular parasites and their spread to non-endemic areas are facilitated. The morbidity and mortality risks have been increasing due to the difficulties encountered by health personnel in the diagnosis of these parasitic infections. Defining them accurately and appropriately can save not only eyesight but also lives.
Topics: Animals; Eye Infections, Parasitic; Global Health; Humans; Parasites; Travel-Related Illness
PubMed: 33269567
DOI: 10.4274/tpd.galenos.2020.6710 -
Proceedings. Biological Sciences May 2019Free-living species vary substantially in the extent of their spatial distributions. However, distributions of parasitic species have not been comprehensively compared...
Free-living species vary substantially in the extent of their spatial distributions. However, distributions of parasitic species have not been comprehensively compared in this context. We investigated which factors most influence the geographical extent of mammal parasites. Using the Global Mammal Parasite Database we analysed 17 818 individual geospatial records on 1806 parasite species (encompassing viruses, bacteria, protozoa, arthropods and helminths) that infect 396 carnivore, ungulate and primate host species. As a measure of the geographical extent of each parasite species we quantified the number and area of world ecoregions occupied by each. To evaluate the importance of variables influencing the summed area of ecoregions occupied by a parasite species, we used Bayesian network analysis of a subset ( n = 866) of the parasites in our database that had at least two host species and complete information on parasite traits. We found that parasites that covered more geographical area had a greater number of host species, higher average phylogenetic relatedness between host species and more sampling effort. Host and parasite taxonomic groups had weak and indirect effects on parasite ecoregion area; parasite transmission mode had virtually no effect. Mechanistically, a greater number of host species probably increases both the collective abundance and habitat breadth of hosts, providing more opportunities for a parasite to have an expansive range. Furthermore, even though mammals are one of the best-studied animal classes, the ecoregion area occupied by their parasites is strongly sensitive to sampling effort, implying mammal parasites are undersampled. Overall, our results support that parasite geographical extent is largely controlled by host characteristics, many of which are subsumed within host taxonomic identity.
Topics: Animal Distribution; Animals; Bayes Theorem; Ecosystem; Geography; Host Specificity; Host-Parasite Interactions; Host-Pathogen Interactions; Mammals; Parasites
PubMed: 31113328
DOI: 10.1098/rspb.2019.0673 -
Pharmaceutical Research Apr 2022Cutaneous parasites are identified by their specific cutaneous symptoms which are elicited based on the parasite's interactions with the host. Standard anti-parasitic... (Review)
Review
Cutaneous parasites are identified by their specific cutaneous symptoms which are elicited based on the parasite's interactions with the host. Standard anti-parasitic treatments primarily focus on the use of specific drugs to disrupt the regular function of the target parasite. In cases where secondary infections are induced by the parasite itself, antibiotics may also be used in tandem with the primary treatment to deal with the infection. Whilst drug-based treatments are highly effective, the development of resistance by bacteria and parasites, is increasingly prevalent in the modern day, thus requiring the development of non-drug based anti-parasitic strategies. Cutaneous parasites vary significantly in terms of the non-systemic methods that are required to deal with them. The main factors that need to be considered are the specifically elicited cutaneous symptoms and the relative cutaneous depth in which the parasites typically reside in. Due to the various differences in their migratory nature, certain cutaneous strategies are only viable for specific parasites, which then leads to the idea of developing an all-encompassing anti-parasitic strategy that works specifically against cutaneous parasites. The main benefit of this would be the overall time saved in regards to the period that is needed for accurate diagnosis of parasite, coupled with the prescription and application of the appropriate treatment based on the diagnosis. This review will assess the currently identified cutaneous parasites, detailing their life cycles which will allow for the identification of certain areas that could be exploited for the facilitation of cutaneous anti-parasitic treatment.
Topics: Animals; Host-Parasite Interactions; Parasites
PubMed: 35313360
DOI: 10.1007/s11095-022-03232-y -
Parasitology Feb 2015A key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a... (Review)
Review
A key part of the life cycle of an organism is reproduction. For a number of important protist parasites that cause human and animal disease, their sexuality has been a topic of debate for many years. Traditionally, protists were considered to be primitive relatives of the 'higher' eukaryotes, which may have diverged prior to the evolution of sex and to reproduce by binary fission. More recent views of eukaryotic evolution suggest that sex, and meiosis, evolved early, possibly in the common ancestor of all eukaryotes. However, detecting sex in these parasites is not straightforward. Recent advances, particularly in genome sequencing technology, have allowed new insights into parasite reproduction. Here, we review the evidence on reproduction in parasitic protists. We discuss protist reproduction in the light of parasitic life cycles and routes of transmission among hosts.
Topics: Animals; Biological Evolution; Eukaryota; Genome; Humans; Life Cycle Stages; Meiosis; Parasites; Parasitic Diseases; Reproduction
PubMed: 25529755
DOI: 10.1017/S0031182014001693 -
PLoS Neglected Tropical Diseases 2015Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing... (Review)
Review
Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing the population biology and reproductive mode of such pests is not only a matter of pure science, but can also be useful for understanding parasite adaptation, as well as how parasitism, specialization (parasite specificity), and complex life cycles evolve over time. Studying this parasite's reproductive strategies and population structure can also contribute key information to the understanding of the epidemiology of associated diseases; it can also provide clues for elaborating control programs and predicting the probability of success for control campaigns (such as vaccines and drug therapies), along with emergence or re-emergence risks. Population genetics tools, if appropriately used, can provide precise and useful information in these investigations. In this paper, we revisit recent data collected during population genetics surveys of different Trypanosoma species in sub-Saharan Africa. Reproductive modes and population structure depend not only on the taxon but also on the geographical location and data quality (absence or presence of DNA amplification failures). We conclude on issues regarding future directions of research, in particular vis-à-vis genotyping and sampling strategies, which are still relevant yet, too often, neglected issues.
Topics: Africa South of the Sahara; Animals; Genetic Variation; Genetics, Population; Humans; Parasitology; Trypanosoma
PubMed: 26491968
DOI: 10.1371/journal.pntd.0003985