Parasite Biodiversity Research Articles

Metazoan parasites associated with marine mollusks inhabiting the China Seas: a review

Parasites in mollusks are often neglected by humans, while some species were reported to be harmful to economic mollusks and caused production decrease. Metazoan parasites of mollusk studies from the China Seas started relatively later than other countries. To promote long-term studies on the distribution and diversity of metazoan parasites of mollusks from the China Seas, a comprehensive review has been carried out based on the available literature. The purpose of this study was to perform a critical review about the metazoan parasites associated with mollusks that are useful for the discovery of new metazoans. This publication summarizes information on metazoan parasites of Chinese mollusks from 1932 to 2024. The information is presented and contains 128 species of parasites, distributed among the higher taxa as follows: Turbellaria (2 species), Trematoda (34 species), Cestoda (1 species), Annelida (38 species), Arthropoda (48 species), Porifera (2 species), Cnidaria (1 species), and Mollusca (2 species). Many records of parasites not identified to the species level are also included. Collectively, this review provides a synopsis of the known metazoan parasites of mollusks from the China Seas, as well as presents the known relationship between metazoan parasites and the mollusks, which will broaden our knowledge on the metazoan parasites of mollusks. It is important as it highlights the lack of metazoan parasite studies done in the China Seas and the need for more parasite biodiversity work.

An interdisciplinary approach to improving conservation outcomes for parasites.

Parasites represent a significant proportion of Earth's biodiversity and play important roles in the ecology and biology of ecosystems and hosts, making them an important target for conservation. Despite increasing calls to prioritize protection for parasites in the academic literature, they remain undervalued and underrepresented in global biodiversity conservation efforts, not least due to the perception that the interests of parasite and host conservation are opposing and the common misconception that parasites are a threat, rather than a benefit, to conservation. We considered whether taking an interdisciplinary approach to parasite conservation research will generate novel insights and solutions concerning why and how parasite conservation should be practiced for the benefit of parasites, their hosts, ecosystems, and people. We argue that 2 of the main barriers to more widespread parasite conservation are the knowledge gap concerning the role of sociocultural factors affecting the willingness to enact parasite conservation and the lack of a consistent and cohesive philosophical basis for parasite conservation. Possible sociocultural barriers to parasite conservation include misconceptions of the risks posed by parasites, taxonomic bias, differences in conservation values, economic constraints, and technical challenges. The use of social science can generate insights into levels of awareness and support for parasite conservation and improve understanding of how human values and attitudes mediate conservation practices concerning parasites. Such knowledge will have a critical role in addressing sociocultural barriers and improving support for parasite conservation. Issues with the current philosophical basis for parasite conservation include contradictory accounts of which parasites merit conservation, insufficient explanation of how different conservation values apply to parasite biodiversity, and the existence of a false antagonism between host and parasite conservation. Greater engagement with philosophical work on environmental ethics and biological unitization will strengthen existing arguments for parasite conservation and will support conservation decision-making processes.

Parasites in a Changing World: Troublesome or in Trouble?

There are plenty of reasons to believe that parasite populations will respond to biodiversity loss, warming, pollution, and other forms of global change. But will global change enhance transmission, increasing the incidence of troublesome parasites that put people, livestock, and wildlife at risk? Or will parasite populations decline in abundance-or even become extinct-suggesting trouble on the horizon for parasite biodiversity? Here, I explain why answers have thus far eluded us and suggest new lines of research that would advance the field. Data collected to date suggest that parasites can respond to global change with increases or decreases in abundance, depending on the driver and the parasite. The future will certainly bring outbreaks of some parasites, and these should be addressed to protect human and ecosystem health. But troublesome parasites should not consume all of our research effort, because this changing world contains many parasite species that are in trouble.

Species of Monogenean Parasites Infesting Cyprinus carpio and Planiliza abu in Lake Balloran Dam-Syria

This study was conducted in Lake Balloran Dam and involved 68 fish specimens, including 23 common carp (Cyprinus carpio) and 45 Abu mullet (Liza abu). Sampling was carried out monthly and randomly from July 2020 to August 2021. The research addressed parasitic infections in these two important species of freshwater fish. This work identifies five parasitic species of monogeneans, three of them were isolated from common carp and identified as species belonging to the genus Dactylogyrus: D. dogieli, D. minutus, and D. extensus. One species was isolated from both the common carp and Abu mullet, and identified as the species Gyrodactylus derjavini, and the other species, G. elegans, was isolated from only the common carp. Dactylogyrus species were primarily isolated from the gills of the studied fish, whereas Gyrodactylus species were found on the skin and fins. This study is of fundamental interest for the knowledge of parasitic biodiversity on the Asian continent that are widespread in vast bodies of water, and the species D. dogieli and G. derjavini were recorded for the first time in Syrian freshwater in this study.

Redescription of Raphidascaris (Ichthyascaris) vicentei (Nematoda: Raphidascarididae) Parasitizing Lutjanid Fishes (Actinopterygii: Lutjanidae) from the Northeast Coast of Brazil, Including First Observation Using SEM.

In this study, 143 lutjanid fishes representing four different species from the Northeast coast off Brazil were analyzed for parasites. The aim of the present study is to provide a detailed redescription of R. (I.) vicentei, collected from lutjanid fishes in Brazil, including the first observation of the species using scanning electron microscopy (SEM). Nematodes found clarified in a crescent glycerin series, were photographed and measured (in mm), and some specimens destined for SEM. The Illustrations were made using an optical microscope with a drawing tube. Nematodes found were identified as Raphidascaris (Ichthyascaris) vicentei, infecting 6.29% of the examined fish. Detailed morphological analysis revealed the following characteristics observed for the first time in this species: labial papillae, narrow lateral alae and the detailed structure of male spicules. These contributions help filling the gaps in the literature and expand the knowledge of this parasite morphology. The presence of R. (I.) vicentei in four lutjanid species may indicates low host specificity, highlighting its adaptability to different hosts. Furthermore, new host records are given. This research provides the most comprehensive morphological description of R. (I.) vicentei to date, generating crucial insights for a better understanding of the parasitic biodiversity off the Brazilian Northeastern coast of Brazil, as well as establishing foundation for future investigations on the ecology and impacts of these parasites in fish populations from this region.

Nomenclatural stability and the longevity of helminth species names

Although most Latin binomial names of species are valid, many are eventually unaccepted when they are found to be synonyms of previously described species, or superseded by a new combination when the species they denote are moved to a different genus. What proportion of parasite species names become unaccepted over time, and how long does it take for incorrect names to become unaccepted? Here, we address these questions using a dataset comprising thousands of species names of parasitic helminths from four higher taxa (Acanthocephala, Nematoda, Cestoda, and Trematoda). Overall, among species names proposed in the past two-and-a-half centuries, nearly one-third have since been unaccepted, the most common reason being that they have been superseded by a new combination. A greater proportion of older names (proposed pre-1950) have since been unaccepted compared to names proposed more recently, however most taxonomic acts leading to species names being unaccepted (through either synonymy or reclassification) occurred in the past few decades. Overall, the average longevity of helminth species names that are currently unaccepted was 29 years; although many remained in use for over 100 years, about 50% of the total were invalidated within 20 years of first being proposed. The patterns observed were roughly the same for all four higher helminth taxa considered here. Our results provide a quantitative illustration of the self-correcting nature of parasite taxonomy, and can also help to calibrate future estimates of total parasite biodiversity.

The first annotated checklist of parasites infecting the one-humped camel, Camelus dromedarius (Artiodactyla: Camelidae), of Saudi Arabia between 1950-2021

Based on the published works of camels in Saudi Arabia, this study is the first checklist of parasites infecting the one-humped camel, Camelus dromedarius in Saudi Arabia between 1950-2021. The present checklist was organized taxonomically in which consist of 75 names representing 4 groups of parasites. The first group is Protozoa with 24 names. Secondly, 13 names of nematodes were reported while there were 12 names of Platyhelminthes. The last group belongs to the Arthropoda which consists of 26 reported species, most of which belong to Ixodida. Based on the resulting checklist, the geographical sampling of these records focuses mainly on the Central, Western, Eastern, and Southern regions, respectively. To date, a few studies have recorded parasites in the North region. The evidence reviewed in this list seems to suggest that further research should be undertaken to investigate the biodiversity of parasites infecting camels from the northern region of Saudi Arabia, which is connected to other continents of Asia, Africa, and Europe.

Wild Animals in Captivity: An Analysis of Parasite Biodiversity and Transmission among Animals at Two Zoological Institutions with Different Typologies.

We have conducted a 10-year-long coprological study of the animals housed in two zoological institutions (ZooAquarium and Faunia, Madrid, Spain) to assess the parasite biodiversity, prevalence, and their relation with host class, diet, and enclosure type (soil type and level of isolation from wild fauna). A total of 4476 faecal samples from 132 mammal species and 951 samples from 86 avian species were examined. The results indicated that only 12.8% of avian species had parasites at least once during the study period, whereas 62.1% of mammal species tested positive. Predominantly, protists (Entamoeba, flagellates, and ciliates) and nematodes (mainly Trichuris) were identified in the findings. Carnivorous species were primarily infected by nematodes, while herbivorous and omnivorous species were mainly infected by protists. The number of infected herbivorous and omnivorous species was significantly greater than carnivorous species. Differences were observed based on soil type (artificial, natural, mixed) and isolation level (isolated/accessible), but these differences were not statistically significant. Several parasites (Entamoeba spp., Giardia spp., Balantidoides coli, Trichuris spp.) could potentially be transmitted between humans and some mammals and birds. Regular animal analyses and a personnel health program in the institutions would minimise transmission risks between zoo animals, wildlife, and humans.

Effects of water quality on fish parasite biodiversity and physiological responses in the host fish Clarias gariepinus from a eutrophic lake subjected to acid mine drainage in South Africa.

Elevated concentrations of contaminants have negative impacts on aquatic organisms and their parasites. Changes in parasite infections have been proposed as a technique for monitoring the health of aquatic ecosystems. Furthermore, alterations in physiological responses (biomarkers) of organisms have also been used to delineate ecosystem quality. Lake Heritage is situated along the Crocodile River in Muldersdrift, Gauteng, South Africa, and is subject to contamination by acid mine drainage. Clarias gariepinus is a well-studied bioindicator species and host to numerous endoparasites and ectoparasites. The aims of this study were to delineate the health status of Lake Heritage through a multifaceted approach by comparing the water quality, biomarker responses, and parasite biodiversity of C. gariepinus, compared to unexposed laboratory-reared fish. Physical and chemical water quality parameters were determined using a hand-held probe, test kits, and element analysis with inductively coupled plasma-mass spectrometry. Biomarker responses in the gill, liver, and muscle tissues from C. gariepinus were assessed for total protein, metallothioneins, superoxide dismutase (SOD), and reduced glutathione (GSH) concentrations and activities of acetylcholinesterase and catalase. Results for water quality variables showed higher pH, nitrate, hardness, and copper levels compared with the South African Target Water Quality Guidelines. Catalase activity and concentrations of SOD and reduced GSH showed a response in C. gariepinus to the water quality. Ectoparasites had lower prevalence and mean intensity than endoparasites. However, there were no differences in the physiological responses between infected and uninfected hosts. The study shows that the eutrophic conditions in Lake Heritage cause biomarker responses in the host when compared to host fish in laboratory conditions. Integr Environ Assess Manag 2024;20:1539-1553. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

A new species of Urocleidoides Mizelle & Price, 1964 from the gills of Schizodon nasutus Kner, 1858 (Characiformes, Anostomidae) in southeastern Brazil.

Based on an integrative approach, this study describes a new species of Urocleidoides infesting Schizodon nasutus in the Paranapanema River basin, Brazil. The new species can be distinguished from its congeners by specific morphological features, including the shape of the male copulatory organ and accessory piece, the ventral bar shape, and the shape and size of the hooks. Molecular analyses, particularly of the 28S rDNA gene, suggest a close relationship between the new species and Urocleidoides paradoxus. The phylogenetic and taxonomic arrangement of Urocleidoides is discussed, as the analyses of the 28S rDNA and COI mtDNA resolved the genus as non-monophyletic, with Diaphorocleidus, Rhinoxenus, and Cacatuocotyle nested within it. Additional morphological and molecular data of other congeneric species are required to investigate the phylogenetic position and classification of Urocleidoides. This study underscores the significance of using integrative approaches in understanding host-parasite associations and phylogenetic relationships, contributing to the description of the freshwater fish parasite biodiversity in South America, particularly in the Paranapanema river basin.

Taxonomy, Biodiversity, and Ecology of Parasites of Aquatic Organisms: A Special Issue

Parasitism is ubiquitous and one of the most successful lifestyles on Earth, with more than 200 independent transitions from non-parasitic ancestors considered only in the kingdom Animalia [...]

Eimeria leuckarti in equid coprolites from the Sassanid Era (2nd–6th century CE) excavated in Chehrabad Salt Mine archaeological site, Iran

ObjectiveThis study reports coccidian oocysts in an equid coprolite dated to the Sassanid Empire (2nd–6th century CE) recovered in Chehrabad Salt Mine archaeological site, Iran. MethodsBetween 2015 and 2017, an archaeoparasitological investigation led to the discovery of an equid coprolite in the Chehrabad Salt Mine archeological site, (Douzlakh), western Iran. Samples were rehydrated using trisodium phosphate solution and were examined by light microscopy. ResultsSeven oocysts of Eimeria leuckarti (Flesch, 1883) were identified; they were in various stages of sporulation. ConclusionThis is the first report of ancient coccidian oocysts from equids. The importance of this observation is discussed, and current knowledge of eimeriid oocysts at archaeological sites is reviewed. SignificanceThe observations of E. leuckarti increases current knowledge of parasite biodiversity in ancient Iran when it rested along the Silk Road, a network of trade routes connecting the East and West that was central to economic, cultural, political, and religious interactions between these regions, and to livestock movement that could contribute to the transmission of the parasites from/to other regions. LimitationsThe contextual information about animal species present in and around the Salt Mine during its working periods, including Achaemenid dynasty (6th to 4th century BCE) and Sassanid era (2nd to 6th century CE), is very limited and does not allow secure conclusions regarding the host origin of the coprolites. Suggestions for Further ResearchApplication of molecular biology tools to identify the correct host origin of the coprolites and to detect more parasite species is advocated.

A Comprehensive Update on Helminth Parasite Biodiversity and Richness in Peruvian Amphibians

This study aimed to comprehensively update and expand the knowledge on the diversity and richness of helminth parasites found in Peruvian amphibians. A systematic search was conducted across primary databases, encompassing both indexed and non-indexed articles, to compile the most recent data. As of the present study, a total of 83 distinct helminth taxa have been documented in association with 78 anuran species of the order Anura, marking a 176.7% increase from previously recorded figures. Nematodes exhibited the highest species richness, totalling 52 taxa (62.65%), followed by trematodes (21 taxa, 25.3%), acanthocephalans and cestodes (4 taxa each, 4.8%), and monogeneans (2 taxa, 2.4%). The overwhelming majority (85.5%) of the collected parasites (71 taxa) were identified as mature helminths, with the remaining 14.5% (12 taxa) in their larval stages. Notably, Cosmocerca brasiliense Travassos, 1925 (Cosmocercidae), and Physaloptera sp. (Physalopteridae) were the most prevalent nematodes, having infected the broadest range of host species. Rhinella marina Linnaeus, 1758 (Bufonidae), emerged as the anuran host with the highest diversity, harboring 17 distinct helminth species. These findings underscore the crucial role of helminth parasites in shaping amphibian ecosystems and their significance as bioindicators of environmental health. Protecting both amphibian hosts and their associated helminth parasites is paramount, as it is intrinsically linked to the preservation of ecological equilibrium within these ecosystems.

“Till death do us apart”: The common destiny of brown hare and its parasite community

Although parasites may threaten individual hosts' survival and reproduction, their role as an essential part of ecosystem functioning and biodiversity has been recognized. In Northern Italy, the hare population has evidently declined since 2008.This paper aims to assess the relationship between host demographic trends and helminth parasite community diversity in a two-year survey in Northern Italy to evaluate the impact of parasites on hosts and confirm the hypothesis that endangered host populations are poor in parasites.In 2013 and 2015 the viscera of 54 and 61 hares legally hunted in agro-ecosystems of the Po Plain were collected. This area is characterized by heavy anthropic pressure: more than 60% of the landscape is represented by agricultural or urbanized territories.No intestinal cestodes were detected. Trichuris sp. and Micipsella numidica were collected in 2015 only; Trichostrongylus retortaeformis, Taenia pisiformis cysticercosis and bronchopulmonary lesions caused by small strongyles were observed in both years. The richness and evenness appeared increased in the second year of the survey, although lower than those obtained by literature data from similar populations examined in the last two decades of 1900.The dominant helminth, T. retortaeformis, was more abundant in individuals with higher weight, while pathological findings were mostly unrelated to this nematode infection; this is consistent with a reduced action, even no harm, of the parasites on the individual host or population level.Our results suggest that the conservation of hosts, environment, and parasites cannot be achieved separately and that parasites and wildlife hosts' destinies are intimately linked, confirming the complexity of ecosystems and the need to contemplate parasite biodiversity in conservation strategies.

Biases in parasite biodiversity research: why some helminth species attract more research than others.

As the number of known and described parasite species grows every year, one might ask: how much do we actually know about these species beyond the fact they exist? For free-living taxa, research effort is biased toward a small subset of species based on their properties or human-centric factors. Here, using a large data set on over 2500 helminth parasite species described in the past two decades, we test the importance of several predictors on two measures of research effort: the number of times a species description is cited following its publication, and the number of times a species' name is mentioned in the scientific literature. Our analysis highlights some taxonomic biases: for instance, descriptions of acanthocephalans and nematodes tend to receive more citations than those of other helminths, and species of cestodes are less frequently mentioned in the literature than other helminths. We also found that helminths infecting host species of conservation concern receive less research attention, perhaps because of the constraints associated with research on threatened animals, while those infecting host species of human use receive greater research effort. Intriguingly, we found that species originally described by many co-authors subsequently attract more research effort than those described by one or few authors, and that research effort correlates negatively with the human population size of the country where a species was discovered, but not with its economic strength, measured by its gross domestic product. Overall, our findings reveal that we have conducted very little research, or none at all, on the majority of helminth parasite species following their discovery. The biases in study effort we identify have serious implications for future research into parasite biodiversity and conservation.

Gut Helminth Assemblages of Glossogobius aureus (Family Gobiidae) in Lake Taal, Philippines

One hundred eighty-three individuals of Glossogobius aureus, native to Lake Taal, Philippines, were collected in 2021–2022. Of these, 4 endohelminths were found and identified: Andracantha gravida (Acanthocephala: Polymorphidae), Schyzocotyle acheilognathi (Platyhelminthes: Bothriocephalidae), Azygia sp. (Platyhelminthes: Azygiidae), and Opegaster minima (Platyhelminthes: Opecoelidae). These helminths represent new host records for G. aureus and provide novel contributions to the recent Philippine parasite biodiversity listing. Among these 4 helminths, Azygia sp. was the most prevalent, had the highest percent dominance and mean intensity, and had a broader range followed by S. acheilognathi, A. gravida, and O. minima, respectively. These findings highlight the need to further explore Lake Taal's parasitofauna, especially with regard to the invasion of S. acheilognathi, and the transmission specificity of O. minima, which can be utilized as a keystone parasite biomarker and in return aid in the management and conservation efforts in Lake Taal.

Metazoan Marine Parasites of Costa Rica: A Review

Many new marine parasite species are added every year. Still, in some places, mainly tropical regions, marine parasites have been little studied. An exhaustive review of the indexed publications where species of parasites are reported in the marine environments of Costa Rica was carried out. The history of research on marine parasites in this region is also reviewed. A total of 146 species of marine parasites have been reported in Costa Rica as parasites of 61 different species of hosts. Most of these parasites correspond to trematodes and cestodes, found mainly in the digestive tract of their vertebrate hosts. In Costa Rica, marine parasites have been studied mainly in sea turtles, elasmobranchs, fish, and dolphins. Most marine parasites have been reported based on morphological identifications of adult stages, and most of the work done so far consists of taxonomic identifications (species reports), with little contribution to the pathology and other aspects of the parasites–hosts interactions. The technical difficulties for research in marine parasitology, the lack of sampling in certain groups of hosts, and the lack of a consolidated research group in marine wildlife parasitology in Costa Rica are factors that have prevented a greater and faster advance in the knowledge of the biodiversity of marine parasites in this country.

Spirocamallanus delirae n. sp. (Nematoda, Camallanidae), a parasite of Propimelodus eigenmanni (Siluriformes: Pimelodidae) from the Brazilian Amazon.

A new species of Spirocamallanus Olsen, 1952 (Camallanidae), is described based on specimens found parasitizing Propimelodus eigenmanni (Siluriformes), an Amazonian fish. The new species has buccal capsule with 15-19 spiral ridges, males with caudal alae supported by 3 pairs of precloacal and 6 pairs of postcloacal papillae, and two terminal spikes on tail end, and females with a digitiform projection ending in two small spikes on tail end. The new species shares characteristics with a group of Neotropical Spirocamallanus that are characterized by the presence of caudal alae, 3 pairs of precloacal papillae, unequal spicules and the presence of spines on the tail tip of males. Several species of this group have been reported from marine environments, in contrast with Spirocamallanus delirae n. sp., which occurs in Amazon freshwaters. Among the Brazilian congeners placed in the referred morphological group are S. rarus, S. freitasi, S. macaensis, and S. halithophus, the last two being parasites of marine fishes. The new species differs from S. rarus (3-4), S. macaensis (12-15), and S. halithophus (10-15) based on the number of spirals in the buccal capsule and from S. fretasi based on the morphology of the larger spicule that is bifid in the former and undivided in the new species. The present description of Spirocamallanus delirae n. sp. adds new data to the biodiversity of parasites from freshwater siluriform catfish in the Neotropical region.

A reconstruction of parasite burden reveals one century of climate-associated parasite decline

Long-term data allow ecologists to assess trajectories of population abundance. Without this context, it is impossible to know whether a taxon is thriving or declining to extinction. For parasites of wildlife, there are few long-term data-a gap that creates an impediment to managing parasite biodiversity and infectious threats in a changing world. We produced a century-scale time series of metazoan parasite abundance and used it to test whether parasitism is changing in Puget Sound, United States, and, if so, why. We performed parasitological dissection of fluid-preserved specimens held in natural history collections for eight fish species collected between 1880 and 2019. We found that parasite taxa using three or more obligately required host species-a group that comprised 52% of the parasite taxa we detected-declined in abundance at a rate of 10.9% per decade, whereas no change in abundance was detected for parasites using one or two obligately required host species. We tested several potential mechanisms for the decline in 3+-host parasites and found that parasite abundance was negatively correlated with sea surface temperature, diminishing at a rate of 38% for every 1 °C increase. Although the temperature effect was strong, it did not explain all variability in parasite burden, suggesting that other factors may also have contributed to the long-term declines we observed. These data document one century of climate-associated parasite decline in Puget Sound-a massive loss of biodiversity, undetected until now.

Endoparasites of marsupials in fragments of the Atlantic rainforest, western Paraná State, Brazil.

Knowledge of taxonomy and biodiversity of parasites is fundamental to better understand ecosystem dynamics. The objective of this study was to describe the helminth fauna of two species of marsupials in five fragments of the Atlantic rainforest in the western region of Paraná State, Brazil. In a total of 4050 trap-nights, the animals were captured using Sherman, Tomahawk, and Pitfall traps, euthanized, necropsied, and their organs inspected for helminths. After identification of the parasites, descriptors of infection, such as prevalence, mean abundance, mean intensity, and range of intensity, were calculated. Collectively, six helminth species were observed in 18 animals. The following five species were observed in Marmosa paraguayana: Viannaia hamata (58.8%), Gracilioxyuris agilisis (52.9%), Travassostrongylus sextus (17.6%), Oncicola luehei (5.9%), and Pritchardia boliviensis (5.9%). Whereas the following two species were observed in Monodelphis dimidiata: Trichohelix tuberculata (100%) and Travassostrongylus sextus (100%). This study represents a new locality record for all helminths described herein, and a new host for four helminth species. This is the first report on the helminth fauna of Monodelphis dimidiata, expanding knowledge about marsupials in the Brazilian Atlantic Forest.