Bladder Parasite Research Articles

Effects of the invasive swim bladder parasite Anguillicola crassus on health and condition indicators in the European eel.

Parasites negatively affect biological processes within their hosts, which may alter for example health, growth, and reproductive ability. Non-native invasive parasites, in particular, may have large effects on the endemic hosts, given that the hosts lack evolved specific defences against such parasites. The swim bladder nematode Anguillicola crassus, an invasive parasite originating from Asia, is found in the European eel (Anguilla anguilla, L. 1758), since the 1980s. We investigated whether A. crassus affected several indicators related to health of the European eel (spleen- and liver size, body fat content and relative condition). Our results indicate that during the continental residency of the eels, infection by A. crassus had no major negative impacts on the investigated health indicators at the generally low infection intensities present in this study (median 2-3 visible parasites). Given that many of the adult eels were found to have swim bladder damage, concerns about their spawning migration through deeper oceanic environments can still be raised. To allow further investigations, we suggest that quantification of swim bladder damage should be implemented in eel-monitoring programs. Compared to other parasite pressure parameters, swim bladder damage provides additional information about past infections and future problems.

First detection and low prevalence of Pearsonema spp. in wild raccoons (Procyon lotor) from Central Europe.

The urinary bladder and lower urinary tract of domestic and wild carnivores can be parasitised by filamentous nematodes from the genus Pearsonema (syn. Capillaria). Infestations are often asymptomatic, but severe courses in dogs and cats have been described. Hosts are infested through the ingestion of earthworms (Lumbricidae) which act as intermediate hosts. Epidemiological studies of Pearsonema in raccoons (Procyon lotor) in North America are scarce and previous studies of urinary bladder parasites of European raccoons did not provide evidence of infestation. We examined urine sediment or rinse water from urinary bladders of 499 wild raccoons from Luxembourg, Poland and five study sites in Germany. Pearsonema eggs were found in the urine sediment of 31 (6.2%) raccoons. Infested animals were found in all study areas with prevalence values ranging from 3.7% to 8.7%. No significant difference in prevalence was found either between animals in urban and rural areas or between sexes and age classes. Based on their morphology, the eggs were likely to be P. plica. Considering their increasing density in Central Europe, raccoons may play a previously overlooked role in environmental contamination with Personema eggs.

Determination of the swim bladder parasite Anguillicola crassus (Nematoda, Dracunculoidea) in the European Eel, Anguilla anguilla (Linnaeus, 1758) from the locality Çamalti Tuzla of Izmir Bay, Eastern Aegean Sea

We, here, aimed to determine the presence of Anguillicola crassus, a swim bladder parasite, in 89 (male: 45, female: 44) dead European eel specimens obtained seasonally between 2020-2021 from a regional fisherman, who has fished with fyke net in the locality Tuzla of Izmir Bay, Eastern Aegean Sea. Out of 21 male European eels caught in winter, only one specimen (TL: 48.5 cm and TW: 247.12 g) had 23 swim bladder parasites (adult nematodes: 15, larvae: 8) and similarly, only one parasite was found in one specimen (TL: 37.5 cm and TW: 88.47 g) of 8 eels caught in spring. No parasite was found in the female eels. At the examinations, it was determined that all adult Anguillicola crassus specimens were females and the minimum-maximum and average length values in adult and larval parasites were, respectively, 1.5-2.5 cm (1.99 ± 0.31) and 0.7-1.3 cm (1.025 ± 2.40). Consequently, the species A. crassus, a swim bladder parasite, was found in European eels from the locality Çamalti Tuzla in two seasons (winter and spring) and this parasitic nematode were only in male eels. This study is a first and remarkable one having evidential value, which shows the presence of the species A. crassus among the eel population in the locality Çamalti Tuzla of Izmir Bay. Besides, it is a population that should be monitored due to the status of Anguilla anguilla on the IUCN red list.

Mutual adaptations between hosts and parasites determine stress levels in eels.

Invasive parasites may severely affect their new hosts. Two invasive parasites occurring in the European eel (Anguilla anguilla) are the Asian swim bladder nematode Anguillicola crassus and the Ponto-caspian acanthocephalan Pomphorhynchus sp., which were introduced to the river Rhine in the early 1980/90s. The Japanese eel (Anguilla japonica), as the native host of A. crassus, developed mutual adaptations to the swim bladder parasite, which are lacking in the European eel. Therefore, after its spread to Europe, infestations of European eels with A. crassus were found to be more severe and caused massive swim bladder wall damages mainly due to the feeding activity of the adult nematodes. A suppression of the immune system also appears to be likely, which allows secondary infections e.g. by bacteria or other parasites in European eels. Acanthocephalans of the genus Pomphorhynchus have not been described so far in Japanese eels, in contrast to European eels, which regularly show infestations with Pomphorhynchus sp. By using these differentially adapted host-parasite associations for experimental studies, host stress responses were examined in the present study in relation to the degree of mutual adaptations between eel hosts and parasites.Under laboratory conditions, Japanese and European eels were each inoculated with A. crassus and Pomphorhynchus sp., respectively, to investigate their stress responses against differently adapted parasites. The stress response was determined by analyzing plasma levels of cortisol, which is the main corticosteroid hormone during stress response of fish. The results show a strong cortisol release in European eels after infestation with A. crassus whereas Japanese eels only react against Pomphorhynchus sp. infestations. These results are consistent with the initial hypothesis that a low degree of host-parasite adaptations lead to stronger host stress responses against the parasite.

Gastrointestinal parasitic infection in laboratory rats: a challenge for researchers

Laboratory animals, especially mice and rats, are commonly used in biomedical researches. This study was designed to evaluate the status of gastrointestinal parasites in Wistar rats using parasitological methods. Sixty Wistar rats in different ages which were being maintained conventionally were selected randomly from laboratory animal house. The contents of the gastrointestinal tract of the rats were examined by parasitological methods. All of the rats under study were infected with at least one parasite. Twelve genera of parasites were detected in the rats, the six of which were protozoa including Giardia muris, Entamoeba muris, Blastocystis spp., Eimeria spp., Tritrichomonas muris, and Cryptosporidium spp., and the six other ones were helminths including Hymenolepis nana, Syphacia muris, Syphacia obvelata, Strongyloides ratti, Trichosomoides crassicauda (bladder parasite), and Aspiculuris tetraptera. G. muris showed the highest prevalence rate (96%) followed by T. muris (95%). In addition, the lowest prevalence rate observed in this study was related to S. obvelata, S. ratti, T. crassicauda, and A. tetraptera, all with 1.5% prevalence. Consequently, it is crucial for researchers to monitor laboratory animals by health surveillance programs, essentially emphasizing the good laboratory practice (GLP) to ensure the quality, consistency, and reproducibility of data in their research.

The effect of foraging and ontogeny on the prevalence and intensity of the invasive parasite Anguillicola crassus in the European eel Anguilla anguilla.

Infection patterns of the invasive Anguillicola crassus nematode were investigated in a population of the European eel Anguilla anguilla where parasite invasion is very recent, Loch Lomond, Scotland. Intensity levels of the parasite were associated with differences in fish ontogeny and trophic ecology. Although eels foraged on both fish and invertebrates, individuals which were smaller and fed on invertebrates (>70% contribution to diet) were found to contain a greater number of swim bladder parasites compared to larger eel with a predominance of fish (>60% contribution) in their diet. Within affected fish, a significant negative relationship was found between fish length and parasite intensity, with smaller individuals having higher parasite intensity than larger individuals. This study indicates that food intake and infection risk are linked in this recently infected host-parasite system. From a management perspective increasing our understanding of how infection intensity and repeated exposure is linked to resource use in an ecosystem is important for the future management of this endangered species in Europe.

The Hsp70 response of Anguillicola species to host-specific stressors.

The present study is based on infection experiments of two different swim bladder parasite species, Anguillicola crassus Kuwahara et al., 1974 and Anguillicola novaezelandiae Moravec and Taraschewski, 1988, which were experimentally transferred to the two eel species Anguilla anguilla Linnaeus, 1758 and Anguilla japonica Temmink and Schlegel, 1846, respectively. The host-parasite groups were selected due to their different grades of mutual adaptation. The main aim of this study was to analyze the stress responses within the parasites, which were confronted with different hosts, i.e. with different stressors related to the respective host. For this purpose, mean intensities, recovery rates, larvae output, and levels of synthesized heat shock proteins (Hsp70) were determined in nematodes of each infection group. Increased stress responses were detected in the endemic system of A. crassus parasitizing A. japonica and A. crassus in its recently acquired host A. anguilla, which seems to be associated with the immune response of the particular host species and the expenditure of energy on producing larvae. A. novaezelandiae showed overall weak activities in its unknown host species A. japonica, with the lowest recovery rate of all examined groups neither featuring elevated Hsp responses, nor a high mean intensity, nor any reproductive output. On the contrary, in A. anguilla, the parasite reached higher recovery rates, mean intensities, and reproductive output, but no increased Hsp70 levels could be detected. The four considered factors proved partially interdependent, whereas few results did not follow a clear pattern.

Migratory history of African longfinned eel Anguilla mossambica from Maningory River, Madagascar: discovery of a unique pattern in otolith Sr:Ca ratios

The migratory life histories were investigated for 30 African longfinned eels (Anguilla mossambica) of the yellow eel stage from the Maningory River, East Madagascar using otolith Sr:Ca ratios and parasite composition. The Sr:Ca ratio patterns of nine eels resembled those of A. mossambica in South Africa and of other anguillids and were classified as “typical” Sr:Ca ratio pattern eels. Typical pattern eels were further classified into freshwater residents (five eels) and habitat shifters (four eels) depending on whether they spent their first several years in saltwater. An unique Sr:Ca ratio pattern was found in 21 eels whereby the Sr:Ca ratios in the yellow eel stage increased drastically to extremely high values of 10 to 30 × 10−3 which have not been observed for any Elopomorpha species. These individuals were categorized as “elevated” Sr:Ca ratio pattern eels. The elevated pattern eels were characterized by significantly older ages, lower somatic growth rates, a much higher intensity and abundance of the gastrointestinal parasite Heliconema africanum and a lower abundance of the swim bladder parasite Anguillicoloides papernai. The extremely elevated Sr:Ca ratios of the yellow eel stage result most likely from inhabiting freshwater areas characterized by a high strontium concentration because the ratios far exceeded the known values for Elopomorpha species. Cyclical lows in the otolith Sr:Ca ratios of the elevated type eels corresponded to annuli, revealing either an overwintering movement pattern between habitats with different Sr:Ca ratios, or a seasonal change in the ambient environment.

Natural Anguillicola novaezelandiae infection—is there seasonality in New Zealand?

Knowledge of natural Anguillicola infections of Short-finned eels (Anguilla australis) in New Zealand is very limited. So far, no study contains data on all life cycle stages of Anguillicola novaezelandiae in naturally infected eels. In order to study the frequency of A. novaezelandiae in New Zealand Short-finned eels, we examined eels of the North and the South Island for the presence of the swim bladder parasite. The results show that A. novaezelandiae is a common parasite of the Short-finned eel. The parasite was present in both regions. Eels from both localities show differences in their infection status with respect to prevalence, abundance and intensity. While eels of the South Island were only infected with larval stages, adult and preadult stages could be detected in eels of the North Island. Nevertheless, infrapopulations at both sites were dominated by larval parasite stages. This unique composition of infrapopulations has never been described for any Anguillicola species before and suggests a seasonal occurrence as a possible reason. Export of live eels should be handled cautiously to prevent the spread of A. novaezelandiae throughout other eel populations.

Molecular evidence for the existence of cryptic species assemblages of several myxosporeans (Myxozoa)

Myxosporeans Chloromyxum cristatum, Chloromyxum fluviatile and Zschokkella nova (Myxozoa) are common gall bladder parasites of the cyprinid fishes frequently persisting as co-infections. Despite the fact that they are believed to be innocuous endocommensals, C. cristatum clearly displays the potential of a serious pathogen since it may pervade fish liver parenchyma and cause its necrosis. Employing the comparison of genetic distances among the myxosporean rDNA sequences and performing phylogenetic analyses, we demonstrate that cryptic species assemblages exist in C. fluviatile and Z. nova. Sequence comparison revealed that Chloromyxum legeri, previously assigned as a junior synonym of C. fluviatile, is a valid species. The same method is used to display the distinction of Z. nova isolates from China and the Czech Republic. We show that C. cristatum is not an assemblage of more species, and our results support the synonymy of Chloromyxum cyprini with C. cristatum. We have developed a multiplex PCR as an effective tool for the detection and discrimination of Z. nova, C. cristatum, and C. fluviatile. It is especially advantageous for the distinction of the non-mature plasmodia of both Chloromyxum species. This method also helped to assess the exact prevalence of these parasites in examined samples and enabled to select single-infected host samples for the intended population studies.

Distribution of Eurasian otter biliary parasites, Pseudamphistomum truncatum and Metorchis albidus (Family Opisthorchiidae), in England and Wales

Gall bladders from 273 otter carcasses, collected throughout England and Wales, were screened to assess the status of gall bladder parasites in the Eurasian otter, Lutra lutra. The digenean Pseudamphistomum truncatum had previously been found in UK otters collected between 2000 and 2007. The parasite was established in Somerset and Dorset but its distribution elsewhere in the UK was largely unknown. In the current study, P. truncatum was also found to be abundant in south Wales, with occasional cases elsewhere, but appears to be absent from the north of England. Overall, 11.7% of otters were infected with 1-238 P. truncatum. A second digenean, Metorchis albidus, previously unreported in British otters, was found in the biliary system of 6.6% of otters. M. albidus appears well established in Suffolk, Norfolk and north Essex but was recorded elsewhere rarely. Both parasites are associated with pathological damage to the otter gall bladder. The recent discovery of these two non-native parasites provides a unique opportunity to assess their impact on native British fauna.

Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

In the summer of 2005, yellow phase American eels Anguilla rostrata were examined for the swim bladder parasite Anguillicola crassus from 26 locations in New England, USA, ranging from the Pawcatuck River, Rhode Island, to the East Machias River, Maine. An additional 12 sites were sampled within Canada during the summers of 2006 and 2007: 7 sites in southern Nova Scotia and 5 sites within the St. Lawrence River system. In 2007, eels were also obtained from New Brunswick, northern Nova Scotia, Prince Edward Island, and Newfoundland through the commercial eel fishery. All locations in Rhode Island (n = 3) and Massachusetts (n = 10) and 7 in Maine (n = 13) had infected eels, with parasite prevalence ranging from 7 to 76%. No eels sampled from southern Nova Scotia or the St. Lawrence River system were infected with the parasite. New Brunswick and northern Nova Scotia had infected eels ranging from 3 to 30% parasite prevalence, with Cape Breton, Nova Scotia, being the furthest north the parasite has been reported in American eels. There was no significant relationship between parasite prevalence and latitude. The present study supports the hypothesis that the parasite is capable of expanding its range further into the Maritimes and could potentially reach the St. Lawrence River system.

Molecular identity, phylogeny and life cycle of Chloromyxum schurovi Shul’man & Ieshko 2003

A myxosporean of the genus Chloromyxum sp., which sporulates in the kidney tubules, was detected in Atlantic salmon, Salmo salar L., and brown trout, Salmo trutta L., from three sites in Scotland. A comparison with other reports of Chloromyxum spores in the kidney of European salmonids suggests that they all refer to the same species, Chloromyxum schurovi [Shul'man BS, Ieshko EP (2003). Parazitologia 37:246-247]. Apart from Chloromyxum majori [Yasutake WT, Wood EM (1957). J Parasitol 43:633-637] which has a different geographical and host range, as well as tissue localisation, this is the only representative of the genus in the kidney of salmonids described so far. This study provides a re-description of C. schurovi including its myxosporean and actinosporean stage, i.e. Neoactinomyxum eiseniellae [Ormieres R, Frezil JL (1969). Protistologica 5:137-144], which was identified by 18S rDNA sequence identity. Results of phylogenetic analysis of the 18S rDNA sequence of C. schurovi and all other Chloromyxum species with published sequences showed that C. schurovi clusters with representatives of other myxozoan genera which inhabit the urinary system, whereas the other Chloromyxum species form a more basic clade together with another gall bladder parasite.

Myxosporean gall bladder parasites of gadid fishes in the North Atlantic: Their geographical distributions and an assessment of their economic importance in fisheries and mariculture

Between 1992 and 2003, samples of four species of gadid fish from the northern North Sea, the Faroe Islands and northern Norway were examined for myxosporean gall bladder parasites. Total numbers of each host species examined were: 665 cod Gadus morhua L., 621 haddock Melanogrammus aeglefinus (L.), 389 saithe Pollachius virens (L.) and 445 whiting Merlangius merlangus (L.). Nine species of myxosporeans were found: Ceratomyxa arcuata Thélohan, 1892, Leptotheca informis Auerbach, 1910, Leptotheca longipes Auerbach, 1910, Myxidium bergense Auerbach, 1909, Myxidium gadi Georgévitch, 1916, Myxidium oviforme Parisi, 1912, Myxidium sphaericum Thélohan, 1895, Sphaeromyxa hellandi Auerbach, 1909, and a hitherto undescribed species of Myxidium. The taxonomy and likely geographical distributions of these and other gall bladder myxosporeans of gadid fish reported from both sides of the North Atlantic are discussed. These myxosporeans fulfil most criteria for use as biological tags in host population studies and some have been used successfully already. They also have potential use as indicators of environmental change and marine pollution. Some species are likely to become serious pathogens in mariculture, particularly of cod and haddock. It is clear from our assessment that a great deal has still to be learned about their taxonomy, host specificities, life cycles and general ecology. For their more efficient use as tags and indicators, and for successful control of infections and the application of preventative measures in mariculture, more information on the their biology and ecology is essential.

INITIAL INFECTION, DISTRIBUTION, AND SEASONAL OCCURRENCE OFHOFERELLUS GILSONI(MYXOZOA) WITHIN A POPULATION OFANGUILLA ROSTRATA(ANGUILLIDAE) IN SOUTHERN NOVA SCOTIA

Recently transformed elvers of Anguilla rostrata, entering the mouth of the East River in the Timber/Connaught Lake watershed (Nova Scotia) from the sea in mid-May, did not develop infections of the urinary bladder parasite Hoferellus gilsoni (Myxozoa) after nearly 3 mo in captivity. However, 40% of elvers collected from the mouth of the river in early June and 80% in late June exhibited patent infections by mid-August. It is speculated that given this initial level of infection, the summer run of elvers (estimated to be 208,000-963,000 individuals annually) represents a significant upstream dispersal of spores. Infections in yellow eel, which has a limited home range, probably contribute to spore dispersal within the home range and downstream through spore drift. Sporogenesis occurred in samples of yellow eel collected over an 8-mo period from April to November. Eel length was similar in 3 widely separated sampling locations in the watershed. Prevalences at these localities were 44, 36, and 57% in April and, by June, reached 76, 70, and 90%, respectively. Prevalences remained near the June levels until sampling ceased in November 1998. Studies on captive fish suggest that H. gilsoni can overwinter in the eel. Data from the study indicate that immediate infection of young elvers entering the system, effective spore dispersal, and a seasonally extended sporogenesis all contribute to the ubiquitous presence of the parasite in the eel population.

The relative importance of bladder versus neotenic stages of Polystoma marmorati and P. umthakathi in natural frog populations in South Africa

AbstractInfection levels of Polystoma marmorati (Polystomatidae: Monogenea) in the painted reed frog, Hyperolius marmoratus, and P. umthakathi in the kloof frog, Natalobatrachus bonebergi, were studied under natural conditions. The recorded prevalence for P. marmorati was generally high in adult frogs and low in tadpoles. In the case of P. umthakathi, the opposite was found with a low prevalence in adult frogs and a very high prevalence in tadpoles. Based on these findings, the hypothesis is presented that for P. marmorati the neotenic stage does not play a determining role and the population is maintained by bladder parasites. For P. umthakathi the neotenic stage appears to be more important than the bladder parasite and the population can probably survive without any significant contribution from bladder parasites.

Notes: Occurrence ofAnguillicola crassus, an Exotic Parasitic Swim Bladder Nematode of Eels, in the Southeastern United States

In February 1995, the Texas Parks and Wildlife Department investigated a south Texas aquaculture facility raising eels for sale in Asian markets. There was concern that the eels were infected with Anguillicola crassus, a parasitic swim bladder nematode detrimental to fisheries for European eel Anguilla anguilla after its introduction from Asia in the early 1980s. Eight of 23 eels examined at the facility were infected with a total of 104 Anguillicola crassus. To determine if the parasite was present in natural populations of eels in North America, wild eels from five Texas rivers (N = 22) and Winyah Bay, South Carolina (N = 8) were examined. No swim bladder parasites were found in the eels from Texas, but one eel from South Carolina was infected with an immature Anguillicola crassus.

Redescription of Trichodina xenopodos Fantham, 1924 (Ciliophora: Peritrichida), a urinary bladder parasite of Xenopus laevis laevis Daudin, 1802, with notes on transmission

Trichodina xenopodos Fantham, 1924, a bladder parasite of the clawed toad Xenopus laevis laevis Daudin, 1802, was originally described by Fantham (1924). Subsequently a redescription was presented by Sandon (1965), but both these descriptions do not conform with the standard uniform characteristics proposed by Lom (1958) and cannot therefore, be accepted as valid species descriptions. A redescription of the species is represented, based on silver-impregnated specimens and adhering to the system of Lom and the refined method recently proposed by Van As & Basson (1989). Laboratory experiments were carried out to examine transmission of the parasite. It was established that the trichodinids can survive for a short period in water outside the urinary bladder. During amplexus male and female toads remain closely associated for an extended period at which time the infection from one host to another may be possible.

EPIZOOTIOLOGY AND HISTOPATHOLOGY OF Chloromyxum trijugum (MYXOSPORA: MYXOSPORIDA) IN CENTRARCHID FISHES FROM IOWA

The gall bladder parasite, Chloromyxum trijugum, shows marked host specificity within the sunfish family Centrarchidae. During 1977-78 80% of 230 bluegills (lepomis macrochirus) in Iowa were infected. Prevalence in green sunfish (L. cyanellus) was lower (17%); one of 2 specimens of the hybrid L. macrochirus x L. cyanellus was infected; orangespotted sunfish (L. humilis) and hybrids (L. humilis x L. macrochirus) were not infected. Intensity of infection in bluegills varied throughout the year. Prevalence of free-floating plasmodia in bluegill gall bladders was highest (100%) during winter and spring months, and decreased to 40-50% during summer and fall. Prevalence of attached plasmodia may remain 80-100% throughout the year. Sporulation and plasmotomy were observed year-round. Plasmodia were attached to underlying epithelial cells by pseudopodia-like projections and were associated with various stages of breakdown in the mucosal layer.

Long-term toxicity of ortho-toluenesulfonamide and sodium saccharin in the rat

In a two-generation lifetime feeding study, 50 male and 50 female weanling Sprague-Dawley rats were included in each of the following dietary treatment groups: control; 2.5 mg ortho-toluenesulfonamide ( o-TS, more than 99.9% pure)/kg/day; 25 mg o-TS/kg/day; 250 mg o-TS/kg/day; 250 mg o-TS/kg/day with 1% NH 4Cl in the drinking water: or 5% sodium saccharin, which contained no detectable amount of o-TS. After 3 months on test, the F 0 rats were bred and 50 pups of each sex, from every group, were weaned onto the parental diets which both generations received for their lifetime. Rats from both generations fed diets providing 250 mg o-TS/kg with 1.0% NH 4Cl in the drinking water or containing 5% sodium saccharin had decreased growth rates, but only the former two had lowered feed consumption. There were no treatment-related effects upon reproduction, longevity, or hematological parameters. The animals were free of the bladder parasite Trichosomoides crassicauda. A few animals developed grossly visible bladder and kidney stones but the incidence of these was not treatment related. The incidence of bladder tumours in male rats fed the 5% saccharin diet was significantly increased in both generations compared to their respective control groups. An evaluation of individual feed consumption data for animals fed saccharin-containing diets did not reveal any statistical difference between the amount of feed consumed by animals which had bladder tumors and those that did not. The incidence of bladder tumors in the o-TS-treated groups and in the female rats fed the 5% saccharin diet was not significantly different from that in control animals.