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Bulletin of Mathematical Biology Feb 2023Hosts can activate a defensive response to clear the parasite once being infected. To explore how host survival and fecundity are affected by host-parasite coevolution...
Hosts can activate a defensive response to clear the parasite once being infected. To explore how host survival and fecundity are affected by host-parasite coevolution for chronic parasitic diseases, in this paper, we proposed an age-structured epidemic model with infection age, in which the parasite transmission rate and parasite-induced mortality rate are structured by the infection age. By use of critical function analysis method, we obtained the existence of the host immune evolutionary singular strategy which is a continuous singular strategy (CSS). Assume that parasite-induced mortality begins at infection age [Formula: see text] and is constant v thereafter. We got that the value of the CSS, [Formula: see text], monotonically decreases with respect to infection age [Formula: see text] (see Case (I)), while it is non-monotone if the constant v positively depends on the immune trait c (see Case (II)). This non-monotonicity is verified by numerical simulations and implies that the direction of immune evolution depends on the initial value of immune trait. Besides that, we adopted two special forms of the parasite transmission rate to study the parasite's virulence evolution, by maximizing the basic reproduction ratio [Formula: see text]. The values of the convergence stable parasite's virulence evolutionary singular strategies [Formula: see text] and [Formula: see text] increase monotonically with respect to time lag L (i.e., the time lag between the onset of transmission and mortality). At the singular strategy [Formula: see text] and [Formula: see text], we further obtained the expressions of the case mortalities [Formula: see text] and how they are affected by the time lag L. Finally, we only presented some preliminary results about host and parasite coevolution dynamics, including a general condition under which the coevolutionary singular strategy [Formula: see text] is evolutionarily stable.
Topics: Animals; Parasites; Virulence; Mathematical Concepts; Models, Biological; Basic Reproduction Number
PubMed: 36853371
DOI: 10.1007/s11538-023-01131-w -
Veterinary Medicine and Science Sep 2021Intestinal parasites have a significant impact on productivity of pigs. Additionally, presence of zoonotic parasites in pig faeces used as fertilizer and ingestion of...
BACKGROUND
Intestinal parasites have a significant impact on productivity of pigs. Additionally, presence of zoonotic parasites in pig faeces used as fertilizer and ingestion of raw or undercooked pork products originated from parasite-infested pigs pose a risk to human health.
OBJECTIVES
The aim of the study was to estimate the prevalence and diversity of gastrointestinal (GI) parasites in indigenous pigs (Sus domesticus) maintained under traditional rearing system in Nepal.
METHODS
Fresh faecal samples (n = 100) were collected from the pigs of varying age and sex maintained in 18 small-scale farms in south-central Nepal. Samples were processed using various standard methods and examined for parasite eggs, cysts or oocysts.
RESULTS
Prevalence of GI parasites in indigenous pigs was 91%, comprising of 14 different genera of protozoans and helminths. Male pigs generally had a higher (97.5%) prevalence of GI parasites than females (87%). While 90% of the suckling and weaner piglets were positive for the GI parasites, all growers and 85% the adult pigs were infected with the parasites. Entamoeba spp. were the primary protozoans in all age groups. Strongyloides sp. was more prevalent helminths in suckling and weaner piglets, whereas Ascarid spp. were higher in both growers and adults. Triplet infection was higher (33.3%) in suckling and weaner piglets, while quadruplet and pentuplet infections were higher (p < .05) among growers (46.7%) and adults (30%), respectively.
CONCLUSIONS
The indigenous pigs harbour a higher prevalence and greater diversity of GI parasites. GI parasitism varies by sex and age of the pigs.
Topics: Animals; Feces; Female; Intestinal Diseases, Parasitic; Male; Nepal; Parasites; Swine; Swine Diseases
PubMed: 34021721
DOI: 10.1002/vms3.536 -
Trends in Ecology & Evolution Jul 2024Migratory animals can bring parasites into resident animal (i.e., non-migratory) home ranges (transport effects) and exert trophic effects that either promote or reduce... (Review)
Review
Migratory animals can bring parasites into resident animal (i.e., non-migratory) home ranges (transport effects) and exert trophic effects that either promote or reduce parasite exposure to resident hosts. Here, we examine the importance of these transport and trophic effects and their interactions for resident parasite dynamics. We propose that migrant transport and trophic effects are impacted by the number of migratory animals entering a resident's home range (migration intensity), the amount of time that migrants spend within a resident's home range (migration duration), and the timing of migrant-resident interactions. We then incorporate migration intensity, duration, and timing into a framework for exploring the net impact of migrant trophic and transport effects on resident animal parasite prevalence.
Topics: Animals; Animal Migration; Host-Parasite Interactions; Population Dynamics; Parasitic Diseases, Animal; Parasites
PubMed: 38355367
DOI: 10.1016/j.tree.2024.01.005 -
The American Naturalist Aug 2023AbstractBrood parasitism involves the exploitation of host parental care rather than the extraction of resources directly from hosts. We identify defining... (Review)
Review
AbstractBrood parasitism involves the exploitation of host parental care rather than the extraction of resources directly from hosts. We identify defining characteristics of this strategy and consider its position along continua with adjacent behaviors but focus on canonical brood parasites, where parasitism is obligate and hosts are noneusocial (thereby distinguishing from social parasitism). A systematic literature survey revealed 59 independently derived brood parasitic lineages with most origins (49) in insects, particularly among bees and wasps, and other origins in birds (seven) and fish (three). Insects account for more than 98% of brood parasitic species, with much of that diversity reflecting ancient (≥100-million-year-old) brood parasitic lineages. Brood parasites usually, but not always, evolve from forms that show parental care. In insects, brood parasitism often first evolves through exploitation of a closely related species, following Emery's rule, but this is less typical in birds, which we discuss. We conducted lineage-level comparisons between brood parasitic clades and their sister groups, finding mixed results but an overall neutral to negative effect of brood parasitism on species richness and diversification. Our review of brood parasites reveals many unanswered questions requiring new research, including further modeling of the coevolutionary dynamics of brood parasites and their hosts.
Topics: Animals; Bees; Host-Parasite Interactions; Biological Evolution; Parasites; Insecta; Birds; Nesting Behavior
PubMed: 37531277
DOI: 10.1086/724839 -
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 -
Current Biology : CB Jun 2022Parasitism has independently evolved multiple times across the entire tree of life, and there are numerous parasitic representatives from every major eukaryote kingdom....
Parasitism has independently evolved multiple times across the entire tree of life, and there are numerous parasitic representatives from every major eukaryote kingdom. In animals alone, parasitism has independently evolved at least 200 times. If there are any organisms that one might think would have access to limitless resources, it would be parasites. You would think that living in or on the body of their host, which serves as both a habitat and a food source, would provide parasites with bountiful resources to maximise every aspect of their existence, especially reproduction. But parasitism is not a loophole out of life history trade-offs. There is still a finite amount of resources that a parasite can obtain and allocate to its many needs. Living in a resource-rich environment has allowed many parasites to grow to sizes that are of multiple orders of magnitude larger than their free-living relatives. But that does not mean that the underlying economy of nature and its limitations are inapplicable to parasites.
Topics: Animals; Biological Evolution; Body Size; Host-Parasite Interactions; Parasites; Reproduction; Symbiosis
PubMed: 35728546
DOI: 10.1016/j.cub.2022.01.059 -
Annals of Parasitology 2020Parasitic zoonosis (PZs) have a cosmopolitan significant impact on public health but they are often omitted in discussions, especially in developing countries. Zoonotic... (Review)
Review
Parasitic zoonosis (PZs) have a cosmopolitan significant impact on public health but they are often omitted in discussions, especially in developing countries. Zoonotic parasites include protozoa, cestodes, nematodes, trematodes and arthropods, and notably in African and Arabian countries have a high prevalence among livestock and man. Through this comprehensive review, we summarize the extant published research of the most significant zoonotic parasites present in some countries of Arabic world and we identify the epidemiology and risk factors for significant infections and suggest some effective control measures. This review might help the researches, governments about the zoonotic impact of these neglected infections for future considerations and application for real control programs.
Topics: Animals; Humans; Livestock; Middle East; Parasites; Parasitic Diseases; Parasitic Diseases, Animal; Prevalence; Risk Factors; Zoonoses
PubMed: 32530589
DOI: 10.17420/ap6602.247 -
Trends in Parasitology Sep 2023Plant parasites take advantage of host developmental plasticity to elicit profound developmental and physiological changes. In the case of plant-parasitic nematodes... (Review)
Review
Plant parasites take advantage of host developmental plasticity to elicit profound developmental and physiological changes. In the case of plant-parasitic nematodes (PPNs), these changes can result in the development of new plant organs. Despite the importance of the development- and physiology-altering abilities of these parasites in pathology, research has historically focused on their abilities to suppress immunity. We argue that, given the dramatic changes involved in feeding site establishment, it is entirely possible that development- and physiology-altering abilities of PPNs may, in fact, dominate effector repertoires - highlighting the need for novel high-throughput screens for development- and physiology-altering 'tools'. Uncovering this portion of the nematode 'toolbox' can enable biotechnology, enhance crop protection, and shed light on fundamental host biology itself.
Topics: Animals; Parasites; Host-Parasite Interactions; Nematoda; Plants
PubMed: 37438213
DOI: 10.1016/j.pt.2023.06.005 -
Parasitology Research May 2023The components that mold the structure of parasitic fauna are used as objects of study in an attempt to find patterns in their distribution. It is known that phylogeny...
The components that mold the structure of parasitic fauna are used as objects of study in an attempt to find patterns in their distribution. It is known that phylogeny (represented by specificity), host ecological traits (for example, feeding habits, position of the water column, reproductive strategies, body size, and age), and the environment affect the distribution and occurrence of parasites. In tropical regions, digeneans show high diversity, and the species Dadaytrema oxycephala is known to parasitize a wide range of host species. In this context, the objective of the present study is to analyze the components that affect the occurrence of D. oxycephala in Neotropical fish. We used data from the literature that contained the abundance of this parasite, as well as the geographic location and host species, and evaluated the influence of ecological traits, specificity, and latitude on parasite abundance, using a generalized linear mixed model (GLMM). The abundance of D. oxycephala can be explained by trophic level and position in the water column and latitude. However, coevolutionary processes are also extremely important, and the distribution of this parasite was not equal, showing high abundance for the genus Piaractus, which are the preferred hosts, even if the parasite is considered generalist. In short, host ecological traits are the important components in the distribution and occurrence of D. oxycephala, as well as the latitude.
Topics: Animals; Fishes; Trematoda; Parasites; Phylogeny; Water; Host-Parasite Interactions; Fish Diseases
PubMed: 36930288
DOI: 10.1007/s00436-023-07822-6 -
Proceedings. Biological Sciences Jul 2022Hosts can avoid parasites (and pathogens) by reducing social contact, but such isolation may carry costs, e.g. increased vulnerability to predators. Thus, many...
Hosts can avoid parasites (and pathogens) by reducing social contact, but such isolation may carry costs, e.g. increased vulnerability to predators. Thus, many predator-host-parasite systems confront hosts with a trade-off between predation and parasitism. Parasites, meanwhile, evolve higher virulence in response to increased host sociality and consequently, increased multiple infections. How does predation shift coevolution of host behaviour and parasite virulence? What if predators are selective, i.e. predators disproportionately capture the sickest hosts? We answer these questions with an eco-coevolutionary model parametrized for a Trinidadian guppy- spp. system. Here, increased predation drives host coevolution of higher grouping, which selects for higher virulence. Additionally, higher predator selectivity drives the contact rate higher and virulence lower. Finally, we show how predation and selectivity can have very different impacts on host density and prevalence depending on whether hosts or parasites evolve, or both. For example, higher predator selectivity led to lower prevalence with no evolution or only parasite evolution but higher prevalence with host evolution or coevolution. These findings inform our understanding of diverse systems in which host behavioural responses to predation may lead to increased prevalence and virulence of parasites.
Topics: Animals; Biological Evolution; Host-Parasite Interactions; Parasites; Poecilia; Predatory Behavior; Virulence
PubMed: 35858064
DOI: 10.1098/rspb.2021.2800