| helminth and arthropod parasites of the brown pelican, pelecanus occidentalis, in puerto rico, with a compilation of all metazoan parasites reported from this host in the western hemisphere. | seven species of helminths and six species of arthropods are reported from 23 of 40 brown pelicans, pelecanus occidentalis, collected from various localities in puerto rico. helminth parasites include three nematodes (contracaecum multipapillatum, contracaecum mexicanum, and eustrongylides sp.), three trematodes (galactosomum darbyi, mesostephanus appendiculatoides, and ribeiroia ondatrae), and one cestode (tetrabothrium sulae). arthropod parasites include colpocephalum occidentalis, neottialges ... | 2002 | 12427338 |
| amphibian deformities and ribeiroia infection: an emerging helminthiasis. | since their widespread appearance in the mid-1990s, malformed amphibians have evoked fear, as well as fascination within the scientific and public communities. recent evidence from field and laboratory studies has implicated infection by a digenetic trematode--ribeiroia ondatrae--as an important cause of such deformities. ribeiroia spp. have a complex life cycle involving planorbid snails, amphibians and water birds. under natural conditions, malformations might promote parasite transmission by ... | 2003 | 12901930 |
| in vitro excystment of the metacercariae of ribeiroia ondatrae. | in vitro excystation studies were done on the metacercarial cysts of ribeiroia ondatrae obtained from naturally infected leopard frogs, rana pipiens. studies were done in petri dish cultures in various media maintained at 41 degrees c. the media consisted of 0.5% trypsin-0.5% bile salts in earle's balanced salt solution at ph 7.8 (tb), 1% acid pepsin (ap) in 0.85% saline adjusted to ph 2 with hcl; acid saline (as) adjusted to ph 2 with hcl, and saline (s). the tb medium, used successfully to exc ... | 2005 | 15678351 |
| adding infection to injury: synergistic effects of predation and parasitism on amphibian malformations. | we explored the importance of interactions between parasite infection and predation in driving an emerging phenomenon of conservation importance: amphibian limb malformations. we suggest that injury resulting from intraspecific predation in combination with trematode infection contributes to the frequency and severity of malformations in salamanders. by integrating field surveys and experiments, we evaluated the individual and combined effects of conspecific attack and parasite (ribeiroia ondatr ... | 2006 | 16995623 |
| aquatic eutrophication promotes pathogenic infection in amphibians. | the widespread emergence of human and wildlife diseases has challenged ecologists to understand how large-scale agents of environmental change affect host-pathogen interactions. accelerated eutrophication of aquatic ecosystems owing to nitrogen and phosphorus enrichment is a pervasive form of environmental change that has been implicated in the emergence of diseases through direct and indirect pathways. we provide experimental evidence linking eutrophication and disease in a multihost parasite s ... | 2007 | 17893332 |
| a ribeiroia spp. (class: trematoda)--specific pcr-based diagnostic. | increased reporting of amphibian malformations in north america has been noted with concern in light of reports that amphibian numbers and species are declining worldwide. ribeiroia ondatrae has been shown to cause a variety of types of malformations in amphibians. however, little is known about the prevalence of r. ondatrae in north america. to aid in conducting field studies of ribeiroia spp., we have developed a polymerase chain reaction (pcr)-based diagnostic. herein, we describe the develop ... | 2007 | 18163367 |
| ribeiroia ondatrae cercariae are consumed by aquatic invertebrate predators. | trematodes amplify asexually in their snail intermediate hosts, resulting in the potential release of hundreds to thousands of free-living cercariae per day for the life of the snail. the high number of cercariae released into the environment undoubtedly increases the probability of transmission. although many individual cercariae successfully infect another host in their life cycle, most fail. factors that prevent successful transmission of cercariae are poorly understood. microcrustaceans and ... | 2007 | 18163369 |
| diversity and disease: community structure drives parasite transmission and host fitness. | changes in host diversity and community structure have been linked to disease, but the mechanisms underlying such relationships and their applicability to non-vector-borne disease systems remain conjectural. here we experimentally investigated how changes in host community structure affected the transmission and pathology of the multi-host parasite ribeiroia ondatrae, which is a widespread cause of amphibian limb deformities. we exposed larval amphibians to parasites in monospecific or heterospe ... | 2008 | 18616550 |
| all hosts are not equal: explaining differential patterns of malformations in an amphibian community. | 1. within a community, different host species often exhibit broad variation in sensitivity to infection and disease. because such differences can influence the strength and outcome of community interactions, it is essential to understand differential disease patterns and identify the mechanisms responsible. 2. in north american wetlands, amphibian species often exhibit extraordinary differences in the frequency of limb malformations induced by the digenetic trematode, ribeiroia ondatrae. by coup ... | 2009 | 18671806 |
| road proximity increases risk of skeletal abnormalities in wood frogs from national wildlife refuges in alaska. | skeletal and eye abnormalities in amphibians are not well understood, and they appear to be increasing while global populations decline. here, we present the first study of amphibian abnormalities in alaska. | 2008 | 18709167 |
| histopathological effects of the intramolluscan stages of zygocotyle lunata, echinostoma trivolvis, and ribeiroia ondatrae on helisoma trivolvis and observations on keratin in the trematode larvae. | the histopathological effects of zygocotyle lunata, echinostoma trivolvis, and ribeiroia ondatrae in naturally infected helisoma trivolvis were studied in hematoxylin and eosin sections of infected digestive glands fixed in 10% neutral buffered formalin. the larval stages of all three trematodes damaged the snail digestive gland. most notable histopathology included disrupted digestive gland tubules, lysed cells, compressed tubules, and edematous spaces between tubules. considerable damage was d ... | 2009 | 19653002 |
| the combined influence of trematode parasites and predatory salamanders on wood frog (rana sylvatica) tadpoles. | predators can have important impacts on host-parasite dynamics. for many directly transmitted parasites, predators can reduce transmission by removing the most heavily infected individuals from the population. less is known about how predators might influence parasite dynamics in systems where the parasite relies on vectors or multiple host species to complete their life cycles. digenetic trematodes are parasitic flatworms with complex life cycles typically involving three host species. they are ... | 2011 | 21384178 |
| helminth parasitism in the neotropical cormorant, phalacrocorax brasilianus, in southern brazil: effect of host size, weight, sex, and maturity state. | forty-seven specimens of neotropical cormorants, phalacrocorax brasilianus, from lago guaíba, guaíba, state of rio grande do sul, brazil (30° 00' s, 51°15' w), were examined for helminth parasites between 1999 and 2003. twenty species of helminth parasites were found: ten digeneans: austrodiplostomum mordax, austrodiplostomum compactum, clinostomum sp., drepanocephalus olivaceus, drepanocephalus spathans, hysteromorpha triloba, ignavia olivacei, paryphostomum segregatum, prosthogonimus ovatus, a ... | 2011 | 21431903 |
| parasite competition hidden by correlated coinfection: using surveys and experiments to understand parasite interactions. | within most free-living species exists a cryptic community of interacting parasites. by combining multiscale field data with manipulative experiments, we evaluated patterns of parasite coinfection in amphibian hosts and their underlying mechanisms. surveys of 86 wetlands and 1273 hosts revealed positive correlations between two pathogenic trematodes (ribeiroia ondatrae and echinostoma trivolvis) both between wetlands and within individual hosts. in infection and coinfection experiments, ribeiroi ... | 2011 | 21608460 |
| presence of ribeiroia ondatrae in the developing anuran limb disrupts retinoic acid levels. | the widespread reports of malformed frogs have sparked interest worldwide to try and determine the causes of such malformations. ribeiroia ondatrae is a digenetic trematode, which has been implicated as one such cause, as this parasite encysts within the developing tadpole hind limb bud and inguinal region causing dramatic limb malformations. currently, the mechanisms involved in parasite-induced limb deformities remain unclear. we sought to investigate whether the level of retinoic acid (ra), a ... | 2011 | 21614545 |
| disease and the extended phenotype: parasites control host performance and survival through induced changes in body plan. | by definition, parasites harm their hosts. however, some forms of parasite-induced alterations increase parasite transmission between hosts, such that manipulated hosts can be considered extensions of the parasite's phenotype. while well accepted in principle, surprisingly few studies have quantified how parasite manipulations alter host performance and survival under field and laboratory conditions. | 2011 | 21633498 |
| experimental exposure of helisoma trivolvis and biomphalaria glabrata (gastropoda) to ribeiroia ondatrae (trematoda). | abstract experimental infections provide an important foundation for understanding host responses to parasites. while infections with ribeiroia ondatrae cause mortality and malformations in a wide range of amphibian second intermediate host species, little is known about how the parasite affects its snail first intermediate hosts or even what species can support infection. in this study, we experimentally exposed helisoma trivolvis, a commonly reported host of r. ondatrae, and biomphalaria glabr ... | 2011 | 21671721 |
| widespread co-occurrence of virulent pathogens within california amphibian communities. | the chytrid fungus batrachochytrium dendrobatidis, ranaviruses, and trematodes (ribeiroia ondatrae and echinostomes) are highly virulent pathogens known to infect amphibians, yet the extent to which they co-occur within amphibian communities remains poorly understood. using field surveillance of 85 wetlands in the east bay region of california, usa, we found that 68% of wetlands had ≥2 pathogens and 36% had ≥3 pathogens. wetlands with high pathogen species richness also tended to cluster spatial ... | 2012 | 22766887 |
| morphological and its2 molecular characterization of ribeiroia cercariae (digenea: psilostomidae) from biomphalaria spp. (gastropoda: planorbidae) in northern argentina. | species of ribeiroia use planorbid snails as intermediate host. since there is little information about these digenean parasites in south america, we aimed to assess whether ribeiroia cercariae from 3 north argentina locations belonged to the same species and differed from ribeiroia cercariae described elsewhere. specimens were obtained from biomphalaria tenagophila and biomphalaria orbignyi (salta province), and biomphalaria occidentalis (corrientes province). morphological traits of cercariae ... | 2015 | 26075730 |
| bottom-up and trait-mediated effects of resource quality on amphibian parasitism. | leaf litter subsidies are important resources for aquatic consumers like tadpoles and snails, causing bottom-up effects on wetland ecosystems. recent studies have shown that variation in litter nutritional quality can be as important as litter quantity in driving these bottom-up effects. resource subsidies likely also have indirect and trait-mediated effects on predation and parasitism, but these potential effects remain largely unexplored. we generated predictions for differential effects of li ... | 2017 | 28027571 |
| host and parasite thermal acclimation responses depend on the stage of infection. | global climate change is expected to alter patterns of temperature variability, which could influence species interactions including parasitism. species interactions can be difficult to predict in variable-temperature environments because of thermal acclimation responses, i.e. physiological changes that allow organisms to adjust to a new temperature following a temperature shift. the goal of this study was to determine how thermal acclimation influences host resistance to infection and to test f ... | 2016 | 27040618 |
| role of antimicrobial peptides in amphibian defense against trematode infection. | antimicrobial peptides (amps) contribute to the immune defenses of many vertebrates, including amphibians. as larvae, amphibians are often exposed to the infectious stages of trematode parasites, many of which must penetrate the host's skin, potentially interacting with host amps. we tested the effects of the natural amps repertoires on both the survival of trematode infectious stages as well as their ability to infect larval amphibians. all five trematode species exhibited decreased survival of ... | 2016 | 26911920 |
| experimental infections of bluegill with the trematode ribeiroia ondatrae (digenea: cathaemasiidae): histopathology and hematological response. | infections by the digenetic trematode, ribeiroia ondatrae, cause severe limb malformations in many north american amphibians. ribeiroia ondatrae also infects fishes as second intermediate hosts, but less is known about the pathology and immune responses initiated in infected fish, even though reports of infected fish date back to early 1900s. to this end, we experimentally exposed juvenile bluegills lepomis macrochirus to three doses of r. ondatrae cercariae and monitored the pathology, parasite ... | 2015 | 26587684 |
| development and application of an edna method to detect and quantify a pathogenic parasite in aquatic ecosystems. | approaches based on organismal dna found in the environment (edna) have become increasingly utilized for ecological studies and biodiversity inventories as an alternative to traditional field survey methods. such dna-based techniques have largely been used to establish the presence of free-living organisms, but have much potential for detecting and quantifying infectious agents in the environment, which is necessary to evaluate disease risk. we developed an edna method to examine the distributio ... | 2015 | 26380540 |
| quantifying larval trematode infections in hosts: a comparison of method validity and implications for infection success. | accurately estimating parasite transmission success and subsequent infection load has important ramifications for a wide range of disease-related questions and research disciplines. recent interest in the role of parasites in amphibian population declines and deformities, for instance, has prompted increased interest in approaches to quantify infection and pathology. here, we introduce a novel method of fluorescently labeling trematode cercariae and optimize its application to interactions betwe ... | 2015 | 25888244 |
| lesser of two evils? foraging choices in response to threats of predation and parasitism. | predators have documented post-encounter (density-mediated) effects on prey but their pre-encounter impacts, including behavioural alterations, can be substantial as well. while it is increasingly evident that this "ecology of fear" is important to understand for natural enemy-victim relationships, fear responses of hosts to the threat of infection by a parasite are relatively unknown. we examined larval amphibian (lithobates pipiens) foraging choices by experimentally manipulating the presence ... | 2015 | 25635765 |
| host density and competency determine the effects of host diversity on trematode parasite infection. | variation in host species composition can dramatically alter parasite transmission in natural communities. whether diverse host communities dilute or amplify parasite transmission is thought to depend critically on species traits, particularly on how hosts affect each other's densities, and their relative competency as hosts. here we studied a community of potential hosts and/or decoys (i.e. non-competent hosts) for two trematode parasite species, echinostoma trivolvis and ribeiroia ondatrae, wh ... | 2014 | 25119568 |
| heterogeneous hosts: how variation in host size, behaviour and immunity affects parasite aggregation. | infection heterogeneity is one of the most fundamental patterns in disease ecology, yet surprisingly few studies have experimentally explored its underlying drivers. here, we used large-scale field assessments to evaluate the degree of parasite aggregation within amphibian host populations followed by a novel experimental approach to assess the potential influence of host size, behaviour and immunity in reproducing such heterogeneity. among 227 wetlands, 2468 hosts and seven parasite species, in ... | 2014 | 24548254 |
| experimental warming drives a seasonal shift in the timing of host-parasite dynamics with consequences for disease risk. | multi-species experiments are critical for identifying the mechanisms through which climate change influences population dynamics and community interactions within ecological systems, including infectious diseases. using a host-parasite system involving freshwater snails, amphibians and trematode parasites, we conducted a year-long, outdoor experiment to evaluate how warming affected net parasite production, the timing of infection and the resultant pathology. warming of 3 °c caused snail interm ... | 2014 | 24401007 |
| host and parasite diversity jointly control disease risk in complex communities. | host-parasite interactions are embedded within complex communities composed of multiple host species and a cryptic assemblage of other parasites. to date, however, surprisingly few studies have explored the joint effects of host and parasite richness on disease risk, despite growing interest in the diversity-disease relationship. here, we combined field surveys and mechanistic experiments to test how transmission of the virulent trematode ribeiroia ondatrae was affected by the diversity of both ... | 2013 | 24082092 |
| experimental infection dynamics: using immunosuppression and in vivo parasite tracking to understand host resistance in an amphibian-trematode system. | although naturally occurring hosts often exhibit pronounced differences in infection and pathology, the relative importance of factors associated with host life history and immunity in explaining such patterns often remains speculative. research in eco-immunology highlights the trade-offs between host physiology and immunity, for which natural variations in disease susceptibility offer a valuable platform to test predictions within this framework. here, we combined use of a novel, in vivo assay ... | 2013 | 23821713 |
| does timing matter? how priority effects influence the outcome of parasite interactions within hosts. | in nature, hosts are exposed to an assemblage of parasite species that collectively form a complex community within the host. to date, however, our understanding of how within-host-parasite communities assemble and interact remains limited. using a larval amphibian host (pacific chorus frog, pseudacris regilla) and two common trematode parasites (ribeiroia ondatrae and echinostoma trivolvis), we experimentally examined how the sequence of host exposure influenced parasite interactions within hos ... | 2013 | 23754306 |
| biomphalaria straminea (mollusca: planorbidae) as an intermediate host of ribeiroia sp. (trematoda: psilostomidae) in brazil. | species of ribeiroia are trematode parasites of birds and mammals that have acquired notoriety since ribeiroia ondatrae was identified as a cause of mortality and malformations in north american amphibians. although species of ribeiroia have been reported in vertebrate hosts in south america, the snails involved in its transmission remain unknown in brazil. during malacological studies conducted at pampulha reservoir, belo horizonte, minas gerais, brazil, between january 2009 and february 2012, ... | 2013 | 23421393 |
| biodiversity decreases disease through predictable changes in host community competence. | accelerating rates of species extinctions and disease emergence underscore the importance of understanding how changes in biodiversity affect disease outcomes. over the past decade, a growing number of studies have reported negative correlations between host biodiversity and disease risk, prompting suggestions that biodiversity conservation could promote human and wildlife health. yet the generality of the diversity-disease linkage remains conjectural, in part because empirical evidence of a rel ... | 2013 | 23407539 |
| parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians. | while often studied in isolation, host-parasite interactions are typically embedded within complex communities. other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g., the dilution effect), yet few studies have experimentally evaluated more than one such mechanism. here, we used data from natural wetlands to design experiments investigating how alternative hosts and predators of parasites mediate trematode (ribeiroia ondatrae) infectio ... | 2012 | 22834364 |
| species diversity reduces parasite infection through cross-generational effects on host abundance. | with growing interest in the effects of biodiversity on disease, there is a critical need for studies that empirically identify the mechanisms underlying the diversity-disease relationship. here, we combined wetland surveys of host community structure with mechanistic experiments involving a multi-host parasite to evaluate competing explanations for the dilution effect. sampling of 320 wetlands in california indicated that snail host communities were strongly nested, with competent hosts for the ... | 2012 | 22486087 |
| noxious newts and their natural enemies: experimental effects of tetrodotoxin exposure on trematode parasites and aquatic macroinvertebrates. | the dermal glands of many amphibian species secrete toxins or other noxious substances as a defense strategy against natural enemies. newts in particular possess the potent neurotoxin tetrodotoxin (ttx), for which the highest concentrations are found in species within the genus taricha. adult taricha are hypothesized to use ttx as a chemical defense against vertebrate predators such as garter snakes (thamnophis spp.). however, less is known about how ttx functions to defend aquatic-developing ne ... | 2017 | 28755852 |