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[Metazoan parasites of the bluewing searobin Prionotus punctatus (Bloch, 1793) (Osteichthyes: Triglidae) from the coastal zone of the State of Rio de Janeiro, Brazil].

Eighty specimens of P. punctatus from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23 degrees 01'S, 44 degrees 19'W), were necropsied between May 2002 to August 2003 to study their infracommunities of metazoan parasites. Were collected 23 species of metazoan parasites: 4 digenean, 2 monogeneans, 2 cestodes, 2 acantocephalans, 6 nematodes, 3 copepods, 2 branchiura, 1 isopod and 1 hirudinean. All fishes were parasitized by two or more parasites species. The nematodes was the predominant taxon (58.6% of parasites collected). Hysterothylacium sp. was the most prevalent, abundant and dominant species. The total of parasites collected and the parasites species richness were significantly correlated with host's total length. Ten species of parasites showed significantly correlation between parasites abundance and total length of P. punctatus. The sex of the host showed positive influence on abundance and prevalence of Hysterothylacium sp., Progrillotia dollfusi Carvajal and Rego, 1983 and Dolops sp. Four pairs of adult endoparasites, one pair of endoparasites larval stages and two pairs of ectoparasites presented association and/or covariation between its prevalences and abundances, respectively. Quantitative dominance of endoparasites in the parasite community of P. punctatus could be related with the predatorious behavior of this fish.

Animals↗
PubMed1989

Metabolic interconnection between the human malarial parasite Plasmodium falciparum and its host erythrocyte. Regulation of ATP levels by means of an adenylate translocator and adenylate kinase.

The metabolic inter-relationships between malarial parasites and their host erythrocytes are poorly understood. They have been investigated hitherto mostly by observing parasite behavior in erythrocyte variants, in metabolically altered erythrocytes, or in cell-free in vitro systems. We have studied the interconnection between the bioenergetic metabolism of host and parasite through compartment analysis of ATP in Plasmodium falciparum-infected human red blood cells, using Sendai virus-induced host cell lysis. ATP concentrations in host and parasite compartments were found to be equal. Inhibitors of mitochondrial activity reduce ATP levels to a similar extent in host and parasite compartments, although only the parasite contains functional mitochondria. It is shown that equalization of ATP levels is brought about by means of an adenylate translocator, probably localized at the parasite plasma membrane, in conjunction with adenylate kinase activity detected both in host and parasite compartments. The translocator is inhibited by compounds which are known to inhibit specifically the translocator of the inner membrane of mammalian mitochondria, with identical inhibitory constants. Addition of these inhibitors to intact infected cells causes a rapid depletion of ATP in the host compartment and a parallel increase in the parasite, suggesting that the parasite supplies ATP to its host cell rather than the reverse.

Adenosine Diphosphate↗
PubMed1977

Isolation and analysis of nucleotides from erythrocyte-free malarial parasites (Plasmodium berghei) and potential relevance to malaria chemotherapy.

Studies using erythrocyte-free preparations of P. berghei were conducted with a view to improving knowledge of parasite metabolism, particularly nucleotide metabolism. The free parasites employed in these studies were prepared by saponin lysis of parasitized mouse erythrocytes in isotonic glucose solutions. A comparative study of post-lytic metabolic activity of free parasites prepared by saponin, ammonium chloride, or osmotic lysis indicated a significantly greater retention of metabolic activity in the saponin-lysis preparations. Separations of nucleoside mono-, di-, and triphosphates extracted from free parasites were performed by means of high pressure liquid chromatography (HPLC), and ATP was additionally measured by luciferin-luciferase assay. Studies designed to differentiate among uptake, phosphorylation, and subsequent incorporation of (3)H-adenosine into nucleic acids of the free parasite strongly suggested that adenosine is metabolized either outside or on the parasite membrane, being first deaminated to inosine and then deribosylated to hypoxanthine. Observations from HPLC and radioisotope precursor studies support a hypothesis in which hypoxanthine may be proposed as being a pivotal substrate for purine salvage by malarial parasites. Some of the key steps in purine salvage and pyrimidine biosynthesis were investigated, using radiolabel uptake studies and HPLC analysis of nucleotides of the free malarial parasite. These studies suggest that hypoxanthine uptake may constitute an important new basis for chemotherapeutic attack on the malarial parasite.

Adenosine Diphosphate↗
PubMed2003

Four-year monitoring of parasite communities in gobiid fishes of the south-western Baltic. I. Guild and component community.

The parasite communities of goby species (Teleostei, Percomorphi) from the south-western Baltic Sea were investigated from 1997 to 2000 in three different seasons. In total, 30 parasite species were found in the guild of four goby spp. from Dahmeshöved (Lübeck Bight). The component community of Pomatoschistus minutus comprised 22, Pomatoschistus pictus 20, Gobiusculus flavescens 18 and Gobius niger 14 parasite species, whereas Pomatoschistus microps from the Salzhaff (Mecklenburg Bight) harboured 24 species. The digenean Podocotyle atomon (ingested with prey) and Cryptocotyle concavum (active penetration) were the most common parasites. Cryptocotyle lingua and the nematode Hysterothylacium sp. in Gobius niger as well as the specialists Aphalloides timmi and Apatemon gracilis (Digenea) in Pomatoschistus microps were also very abundant. There were large changes in the parasite communities within the years as well as between the seasons of a year; only Gobius niger presented rather homogeneous communities. The ratio of core parasite species in the hosts was at most 28% ( Gobiusculus flavescens) and at least 9% ( Gobius niger). The core species can attain their maximum values at different seasons, which is not only influenced by the parasite but also by the host species. It is concluded that the composition of parasite communities was predominantly determined by the ways of life of the host as well as of the parasite species. Another important factor is the population density of intermediate hosts.

Animals↗
PubMed2005

Larval helminths in intermediate hosts: does competition early in life determine the fitness of adult parasites?

Density-dependent effects on parasite fitness have been documented from adult helminths in their definitive hosts. There have, however, been no studies on the cost of sharing an intermediate host with other parasites in terms of reduced adult parasite fecundity. Even if larval parasites suffer a reduction in size, caused by crowding, virtually nothing is known about longer-lasting effects after transmission to the definitive host. This study is the first to use in vitro cultivation with feeding of adult trematodes to investigate how numbers of parasites in the intermediate host affect the size and fecundity of adult parasites. For this purpose, we examined two different infracommunities of parasites in crustacean hosts. Firstly, we used experimental infections of Maritrema novaezealandensis in the amphipod, Paracalliope novizealandiae, to investigate potential density-dependent effects in single-species infections. Secondly, we used the crab, Macrophthalmus hirtipes (Ocypodidae), naturally infected by the trematodes, M. novaezealandensis and Levinseniella sp., the acanthocephalan, Profilicollis spp., and an acuariid nematode. These four helminths all develop and grow in their crustacean host before transmission to their bird definitive host by predation. In experimental infections, we found an intensity-dependent establishment success, with a decrease in the success rate of cercariae developing into infective metacercariae with an increasing dose of cercariae applied to each amphipod. In natural infections, we found that M. novaezealandensis-metacercariae achieved a smaller volume, on average, when infrapopulations of this parasite were large. Small metacercariae produced small in vitro-adult worms, which in turn produced fewer eggs. Crowding effects in the intermediate host thus were expressed at the adult stage in spite of the worms being cultured in a nutrient-rich medium. Furthermore, excystment success and egg-production in M. novaezealandensis in naturally infected crabs were influenced by the number of co-occurring Profilicollis cystacanths, indicating interspecific interactions between the two species. Our results thus indicate that the infracommunity of larval helminths in their intermediate host is interactive and that any density-dependent effect in the intermediate host may have lasting effects on individual parasite fitness.

Acanthocephala↗
PubMed2006

Vector-borne parasites decrease host mobility: a field test of freeze or flee behaviour of willow ptarmigan.

Transmission mode has been suggested to be a strong predictor of virulence. According to theory, the transmission of vector-borne parasites should be less dependent on host mobility than directly transmitted parasites. This could select for increased exploitation of host resources in parasites transmitted by vectors, which may be manifested as higher virulence. Here, we test the prediction that there is an association between transmission mode and the effect on host mobility by comparing parasite infection levels and mobility in willow ptarmigan (Lagopus lagopus L.). We examined the endoparasite infracommunities of individual hosts to obtain annual, quantitative data on four vector-transmitted species (Leucocytozoon lovati, Trypanosoma avium, Haemoproteus mansoni and microfilaria), two directly transmitted species (Trichostrongylus tenuis and Eimeria sp.) and two species with indirect life cycles (Hymenolepis microps and Parionella urogalli). We then used observed variations in freeze-or-flee responses of individual willow ptarmigan to assess whether parasite intensities were related to scored freezing responses. From a field data set covering a period of 9 years from a single area, we found that stronger freezing responses were associated with higher intensities of vector-borne parasites, especially with higher intensities of the haemosporidian L. lovati. Freezing responses were not associated with parasites transmitted in other ways. Thus, high intensities of vector-borne parasites tended to reduce host movements, while parasites with other transmission modes did not.

Animals↗
PubMed2004

Expression of anti-apoptotic factors in cells parasitized by second-generation schizonts of Eimeria tenella and Eimeria necatrix.

Intracellular infections by parasites require a functional anti-apoptotic mechanism for parasite survival within the host cell. The intracellular cycle of Eimeria tenella and Eimeria necatrix in chicken intestinal cells involves the maturation of schizonts within the epithelial cells lining the crypt lumen of the ceca (E. tenella) and jejunum (E. necatrix). After invasion, these cells detach from the epithelial layer and migrate into the underlying connective tissue, where maturation of second-generation schizonts takes place. However, the detached epithelial cells that harbour the parasite and localize in the lamina propia do not undergo apoptosis despite the fact that they are parasitized cells and are located in an inappropriate microenvironment. In this study we consider the hypothesis that E. tenella and E. necatrix may inhibit the host cell apoptosis that accompanies parasite-mediated transformation during late schizogony. To that end, the expression of both NF-kappaB, a transcriptional factor that blocks parasite-induced apoptosis, and bcl-xL, an anti-apoptotic protein induced by NF-kappaB, were studied in the host cell during the maturation of second-generation schizonts. In addition, the expression of the phosphorylated inhibitor of NF-kappaB, p-IkBalpha, was also studied to further confirm NF-kappaB activation. Immunocytochemical techniques, flow cytometric and blott analysis were applied by using polyclonal antibodies that specifically react with bcl-xL, p-IkBalpha, and NF-kappaB to detect these anti-apoptotic proteins in the parasitized cell. Our results offer evidence that both these coccidial species first induce NF-kappaB activation to protect the transformed parasitized cells from apoptosis, allowing the second-generation schizonts to mature, and later, after complete schizonts maturation, cause NF-kappaB inhibition to trigger host cell apoptosis in order to facilitate the escape of merozoites. To determine whether inhibition of the NF-kappaB pathway would induce apoptosis of the host cell, a protease inhibitor (TPCK), which induces apoptosis by mediating inhibition of IkB phosphorylation, was administered to parasitized chickens.

Animals↗
PubMed2004

Bermudagrass management in the Southern Piedmont USA. V: Gastrointestinal parasite control in cattle.

Parasite-free pastures would improve cattle health and performance, resulting in possible economic return to producers. Our objective was to determine the effect of a single series of anthelmintic treatment of steers prior to stocking on Coastal bermudagrass pastures, during five consecutive summers, on the parasite burden in cattle. The site for this experiment had been conventionally cropped for several decades, with no exposure to cattle, and would be expected to be relatively free of nematode larvae. The experimental design was a randomized complete block (landscape features) with a split plot arrangement of treatments where main plots were pasture fertilization treatments (mineral, clover plus mineral, and broiler litter) and split plots were low and high forage mass. Anthelmintic treatment included pour-on ivermectin on day -21, albendazole on day -7, and injectable ivermectin 48 h prior to stocking of pastures, with the cattle remaining in drylot during the 48-h period prior to being placed on the experimental paddocks. All steers received only one series of treatments during any given year. Yearling Angus steers (Bos taurus) were managed in a put-and-take grazing system with three "tester" steers assigned to each paddock and "grazer" steers added or removed at 28-day intervals. From 1994 to 1998, steers grazed the paddocks for a 140-day period from mid May until early October each year. Fecal samples for worm egg counts were obtained on day 0 and at 28-day intervals, thereafter. On all sampling days after day 0, samples were obtained only from tester animals. Over the 5-year period, the mean eggs per gram of feces (epg) gradually increased from 0 (following treatment) to a mean of 2.2 (range from 0.7 to 3.0) by the end of the grazing season (the last sampling date) in October. Although the epg were not zero, they were below threshold levels that would allow development of a parasite burden in cattle. In traditional management systems, cattle graze parasite-contaminated pastures; therefore, parasites negatively impact growth and productivity throughout the entire grazing period. Periodic anthelmintic treatments simply give a temporary reprieve from those parasitic infections. Conceptually, using the current grazing system, it should be possible to maintain these pastures in a parasite-free status indefinitely; however, from a drug resistance perspective, it would be most applicable in sod-based rotation systems where cattle graze from two to five years before land is returned to row-crops. By removing the effect of parasites, cattle can grow without the physiological constraints that gastrointestinal parasites place on appetite, digestion, nutrient utilization, and general well being.

Albendazole↗
PubMed2006

Species diversity and acquisition of gastrointestinal parasites in calves aged 0-13 months in periurban livestock production in Mali.

Post-mortem inspections on 51 calves were conducted to investigate acquisition and spectrum of gastrointestinal parasites in young calves in periurban livestock production in Mali. Generalized linear models with herd as a repeated effect were used to test the influence of management, age and season of birth on parasite numbers and diversity. Parasite number and burden increased with age. In the age class 4-13 months animals carried already up to eight different gastrointestinal parasite species. Parasite spectrum found included 11 nematodes, 3 cestodes and 1 protozoan parasite. The most frequent parasite species found were Haemonchus placei (age class 0-1 month: 7%, 1-4 months: 38%, 4-13 months: 69%), Cooperia pectinata (0%, 33% and 44%) and C. punctata (0%, 33% and 38%). Calves born during the rainy season had higher parasite burden and species diversity than calves born during the dry season. Calves kept under modernised management excreted more Strongyloides papillosus eggs than calves kept under traditional management. Calves acquired most of the parasites occurring in adult bovines in West Africa within their first year of life.

Age Factors↗
PubMed1990

Parasite diversity and the evolution of diploidy, multicellularity and anisogamy.

It may be reasonably assumed that a diversity of parasite genotypes in any one cell or organism is more harmful than a population of uniform genotypes. If this is accepted the following consequences follow: (i) Parasite mixing, due to cytoplasm mixing, at the time of zygote formation is a new and additional cost of sex. The rapid divisions typical of zygotic cleavage may be viewed as an adaptation to minimize the degree of mixing of parasites in each daughter cell. The faster the divisions the less chance parasite populations have to grow and mix. Mitosis is the fastest form of cell division. Prolongation of the diploid phase follows as a consequence of mitosis in a diploid zygote. This view is unusual in that it demands no advantage per se to the possession of two chromosome sets. (ii) The cells of the blastula formed from rapid zygotic divisions are different as regards their symbiotic inclusions. If the right to gametogenesis is restricted, then every replicator symbiont and nuclear genome alike and hence every cell of the developing embryo, will have an incentive to compete. Selection between the clonal blastula cells would result in the cells of low parasite diversity forming the gametes. Thus, germ line restriction is in the interests of the nuclear genome. Controlling the right to gametogenesis is only possible if the blastula remains intact. Hence, multicellularity might have evolved so as to enable the limitation of the right to gametogenesis and hence reduce the parasite diversity of gametes. Inter-cell competition during embryogenesis is central to Buss's seminal notion of the evolution of developmental complexity within the metazoa. The above theory provides the missing motive force behind such competition. (iii) For a given zygote size, the fittest zygotes are those produced by the gametes most disparate in size because these have a lower diversity of parasites. This may be the advantage of anisogamy. The novelty of this new view of anisogamy is that it puts a premium on sperm being very small, in order to exclude parasites from sperm cytoplasm. The hypothesis is briefly tested by examining if there are alternative means of parasite limitation in organisms with large gametes.

Animals↗
PubMed1988

A model of encounters between host and parasite populations.

A simulation model of the encounter between host and parasite populations is described. The model is two-dimensional in that it represents hosts and parasites as sums of random numbers. It allows for the manipulation of host and parasite numbers, areas of interaction, congruity of geographic ranges, parasite infectivity, and reproduction, or non-reproduction, of the parasite. The model generates parasite distributions (number of hosts vs. parasite/host classes) and their parameters (prevalence, mean number of parasites/host, variance/mean ratio as a measure of aggregation), and thus reveals the manner in which these parameters vary under different encounter conditions, i.e. their "behavior". Simulation results indicated that the behavior of parasite population mean, prevalence, and degree of aggregation was primarily a function of the rate at which infective stages were supplied to the system. In cases in which infective stages were continuously available, prevalence rose rapidly to nearly 100%, with increasing infectivity and parasite numbers, and the populations were not particularly aggregated. When infective stages were introduced in single large waves, both mean and prevalence remained low and the parasite populations were highly aggregated. Model results were compared with published data sets. The latter were also seen to fall into the two general categories of parameter behavior.

Animals↗
PubMed2001

The structure of parasite component communities in brackish water fishes of the northeastern Baltic Sea.

We used nestedness analysis to seek non-random patterns in the structure of component communities of metazoan parasites collected from 31 sympatric fish species from the northeastern Bothnian Bay, the most oligohaline area of the Baltic Sea. Only 8 marine parasite species were found among the 63 species recorded, although some marine fish species reproduce in the bay and others occasionally visit the area. Marine parasite species can utilize both freshwater and marine fish species as intermediate or final hosts, and marine fish can harbour freshwater parasite species. This exchange of parasite species between marine and freshwater fish has probably resulted from ecological factors acting over short time scales rather than from evolutionary processes acting over longer time; the key factor probably being the immediate presence of suitable intermediate and definitive hosts. Marine fish were expected to harbour species-poor parasite communities consisting mainly of generalists acquired from the sympatric freshwater fish species, which would result in a nested pattern among the different component communities. However, an anti-nested pattern was found in the component communities of metazoan parasites of fishes from the Bothnian Bay. A likely explanation for the observed pattern is that there are specialist parasite species, the majority of which are cestodes, in some of the freshwater fish species which otherwise have depauperate parasite communities.

Animals↗
PubMed2004

Multiple parasite infections and their relationship to self-reported morbidity in a community of rural Côte d'Ivoire.

BACKGROUND: Concomitant parasitic infections are common in the developing world, yet most studies focus on a single parasite in a narrow age group. We investigated the extent of polyparasitism and parasite associations, and related these findings to self-reported morbidity. METHODS: Inhabitants of 75 randomly selected households from a single village in western Côte d'Ivoire provided multiple faecal specimens and a single finger prick blood sample. The Kato-Katz technique and a formol-ether concentration method were employed to screen faecal samples for Schistosoma mansoni, soil-transmitted helminths and intestinal protozoa. Giemsa-stained blood smears were analysed for malaria parasites. A questionnaire was administered for collection of demographic information and self-reported morbidity indicators. RESULTS: Complete parasitological data were obtained for 500/561 (89.1%) participants, similarly distributed among sex, with an age range from 5 days to 91 years. The prevalences of Plasmodium falciparum, hookworms, Entamoeba histolytica/E. dispar, and S. mansoni were 76.4%, 45.0%, 42.2%, and 39.8%, respectively. Three-quarters of the population harboured three or more parasites concurrently. Multivariate analysis revealed significant associations between several pairs of parasites. Some parasitic infections and the total number of parasites were significantly associated with self-reported morbidity indicators. CONCLUSIONS: Our data confirm that polyparasitism is very common in rural Côte d'Ivoire and that people have clear perceptions about the morbidity caused by some of these parasitic infections. Our findings can be used for the design and implementation of sound intervention strategies to mitigate morbidity and co-morbidity.

Adolescent↗
PubMed2006

One day is enough: rapid and specific host-parasite interactions in a stickleback-trematode system.

Red Queen models of host-parasite coevolution are based on genotype by genotype host-parasite interactions. Such interactions require a genotype specific host defence and, simultaneously, a genotype specific parasite infectivity. Specificity is defined here as defence or infection ability successful against only a subset of genotypes of the same species. A specific defence depends on detectable genotypic variation on the parasite side and on a host defence mechanism that differentiates between parasite genotypes. In vertebrates, the MHC-based adaptive immune system can provide such a defence mechanism, but it needs at least several days to get fully mounted. In contrast, the innate immune system is immediately ready. The trematode parasite species used here reaches the immunologically protected eye lens of its three-spined stickleback (Gasterosteus aculeatus) host within 24 h. Thus, it disappears too fast for the fully mounted MHC-based adaptive immune system. In a complete cross-infection experiment using five fish-families and five parasite-clones, we found for the first time fish-family by parasite-clone interactions in vertebrates, although the parasite was only exposed to the immune system for maximally one day. Such interactions require a fast genotype specific defence, suggesting the importance of other defence mechanisms than the too slow, fully mounted adaptive immune system in vertebrates.

Adaptation, Physiological↗
PubMed2006

Niche metabolism in parasitic protozoa.

Complete or partial genome sequences have recently become available for several medically and evolutionarily important parasitic protozoa. Through the application of bioinformatics complete metabolic repertoires for these parasites can be predicted. For experimentally intractable parasites insight provided by metabolic maps generated in silico has been startling. At its more extreme end, such bioinformatics reckoning facilitated the discovery in some parasites of mitochondria remodelled beyond previous recognition, and the identification of a non-photosynthetic chloroplast relic in malarial parasites. However, for experimentally tractable parasites, mapping of the general metabolic terrain is only a first step in understanding how the parasite modulates its streamlined, yet still often puzzlingly complex, metabolism in order to complete life cycles within host, vector, or environment. This review provides a comparative overview and discussion of metabolic strategies used by several different parasitic protozoa in order to subvert and survive host defences, and illustrates how genomic data contribute to the elucidation of parasite metabolism.

Animals↗
PubMed2004

Community ecology of the metazoan parasites of white sea catfish, Netuma barba (Osteichthyes: Ariidae), from the coastal zone of the state of Rio De Janeiro, Brazil.

Between March 2000 and April 2001, 63 specimens of N. barba from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23 degrees 0' S, 44 degrees 19' W), Brazil, were necropsied to study their infracommunities of metazoan parasites. Fifteen species of metazoan parasites were collected: 2 digeneans, 1 monogenean, 2 cestodes, 1 acantocephalan, 2 nematodes, 6 copepods, and 1 hirudinean. Ninety-six percent of the catfishes were parasitized by at least one metazoan parasite species. A total of 646 individual parasites was collected, with mean of 10.3 +/- 16.6 parasites/fish. The copepods were 37.5% of the total parasite specimens collected. Lepeophtheirus monacanthus was the most dominant species and the only species with abundance positively correlated with the host total length. Host sex did not influence parasite prevalence or mean abundance of any species. The mean diversity in the infracommunities of N. barba was H = 0.130 +/- 0.115 with no correlation with host's total length and without differences in relation to sex of the host. One pair of endoparasites (Dinosoma clupeola and Pseudoacanthostomum floridensis) showed positive association and covariation between their abundances and prevalences. The parasite community of N. barba from Rio de Janeiro can be defined as a complex of species with low prevalence and abundance and with scarcity of interspecific associations. However, because of both the presence of assemblages of sympatric ariid species as well as the spawning behavior characteristic of these fishes, additional comparative studies of the parasite component communities of ariids are necessaries to elucidate this pattern.

Animals↗
PubMed2006

Parasitic community of Fransciscodoras marmoratus (Reinhardt, 1874) (Pisces: Siluriformes, Doradidae) from the upper São Francisco River, Brazil.

One hundred and thirteen specimens of Franciscodoras marmoratus (Reinhardt, 1874) were collected in the upper São Francisco River (18 degrees 12' 32" S, 45 degrees 15' 41" W, state of Minas Gerais) between September, 1999 and January, 2004 to investigate their parasite fauna. From this total, 45 (39.8%) were afflicted by at least one parasite species. The parasitic richness consisted of six species represented by Hirudinea (n = 20), Monogenoidea (n = 25), Eucestoda (n = 55), Nematoda (n = 1, n = 2) and Acanthocephala (n = 41) found in the dry and wet periods making a total of 144 specimens. Proteocephalus renaudi Chambrier & Vaucher, 1994 was the only species with prevalence higher than 10% and a typical aggregate distribution pattern. The prevalence, intensity and abundance of P. renaudi were not influenced by the total length or sex of the hosts or by the collection periods. The relative condition factor indicated that the health of the P. renaudi hosts was not significantly affected in relation to fish not infected by parasites. The fish stocked in tanks before necropsy were opportunistically infested by Lernaea cyprinacea Yashuv, 1959. The various parasites found indicate that F. marmoratus is omnivorous and a potential definitive host. The parasite species, except for Acanthocephala, have expanded their known geographic distribution to the São Francisco River Basin. The parasite community was considered isolationist because of the low endoparasite diversity, infrapopulations with low intensity, lack of evidence of parasite interactions and sparse signs of parasite aggression against their hosts.

Animals↗
PubMed2004

Temporal changes in the prevalence of parasites in two Oregon estuary-dwelling fishes.

The parasite faunas of juvenile English sole (Parophrys vetulus) in 1971-1972 and staghorn sculpin (Leptocottus armatus) in 1971 from Yaquina Bay, Oregon, were compared with faunas found in the same estuary in 1997-2000 (English sole) and 1999-2000 (staghorn sculpin). The 7 most commonly occurring parasites in 1971 were compared with the same species observed during the same month and sampling sites in 1997-2000. Multivariate community analysis of juvenile English sole parasites supported the suggestion that the 1971 parasite data were representative of the early-1970s time period. Four of the parasite species infecting English sole and 6 of those infecting staghorn sculpins had significantly lower prevalences in 1997-2000. Parasite species with significantly lower prevalences also had reduced intensity levels. One parasite (Glugea stephani) of English sole increased in prevalence in the 1997-2000 samples in association with the warm estuarine temperatures during the 1997 El Niño year. Although the causes for the changes in occurrence of other parasites were not determined, ecological changes in Yaquina Bay that may have influenced parasite ecology include apparent changes in the estuary ichthyofauna that occurred between the sampling periods. Such changes could be associated with increases in the number of California sea lions (Zalophus californianus) subsequent to establishment of the Marine Mammal Protection Act in 1972.

Acanthocephala↗