effects of ichthyophonus hoferi on condition indices and blood chemistry of experimentally infected rainbow trout (oncorhynchus mykiss).body condition, hepatosomatic index and blood chemistry of oncorhynchus mykiss experimentally infected with a tissue dwelling fish pathogenic fungus, ichthyophonus hoferi, were monitored over a 6 wk period. this was to determine whether the infection constituted a stress manifest by changes in the hypothalamic-pituitary interrenal axis, and especially plasma cortisol levels. infection caused anaemia and leucopenia but did not change the condition, hepatosomatic indices, or plasma chloride, chole ...19902388355
a novel clade of protistan parasites near the animal-fungal divergence.sequences of nuclear-encoded small-subunit rrna genes have been determined for representatives of the enigmatic genera dermocystidium, ichthyophonus, and psorospermium, protistan parasites of fish and crustaceans. the small-subunit rrna genes from these parasites and from the "rosette agent" (also a parasite of fish) together form a novel, statistically supported clade. phylogenetic analyses demonstrate this clade to diverge near the animal-fungal dichotomy, although more precise resolution is p ...19968876236
parasites of fingerling herring clupea harengus l.: ecology and fine morphology.the parasite fauna of young-of-the-year herring clupea harengus l., off gullmarsfjord and brofjorden, west coast of sweden, was studied between may and october for 4 years, from 1994 to 1997. fifteen species of parasites were found: two protozoa - trichodina sp. and ceratomyxa auerbachi; one species of uncertain affinity - ichthyophonus hoferi; two monogenea - gyrodactylus harengi and pseudanthocotyloides heterocotyle; five digenea - cryptocotyle lingua metacercariae, cercaria pythionike metacer ...200717578600
pcr testing can be as accurate as culture for diagnosis of ichthyophonus hoferi in yukon river chinook salmon oncorhynchus tshawytscha .we evaluated the comparability of culture and pcr tests for detecting ichthyophonus in yukon river chinook salmon oncorhynchus tshawytscha from field samples collected at 3 locations (emmonak, chena, and salcha, alaska, usa) in 2004, 2005, and 2006. assuming diagnosis by culture as the 'true' infection status, we calculated the sensitivity (correctly identifying fish positive for ichthyophonus), specificity (correctly identifying fish negative for ichthyophonus), and accuracy (correctly identify ...201323836767
pcr testing for diagnosis of ichthyophonus hoferi: comment on hamazaki et al. (2013).it is our opinion that hamazaki et al. (2013; dis aquat org 105:21-25) overstate the usefulness of pcr as a field diagnostic technique and underestimate the accuracy and utility of in vitro explant culture. in order for field diagnostic studies to be meaningful they should accurately and dependably identify the infected individuals within a population, both subclinical and clinical cases. although explant culture, like most techniques, can miss some infected individuals, 'false positives' are im ...201324192004
pcr testing for diagnosis of ichthyophonus hoferi: reply to lapatra & kocan (2013).lapatra & kocan (2013) critiqued our paper hamazaki et al. (2013; dis aquat org 105:21-25) for data not supporting the conclusions of 'pcr testing is as accurate as cultureā€¦', but they neither pointed out what part of our data did not support our conclusion, nor did they provide any contrary scientific evidence supporting their argument that pcr testing is less accurate than culture. in the absence of any contradictory data, we stand by our data and our conclusion: pcr test is as suitable as cul ...201324192005
disease surveillance of atlantic herring: molecular characterization of hepatic coccidiosis and a morphological report of a novel intestinal coccidian.surveillance for pathogens of atlantic herring, including viral hemorrhagic septicemia virus (vhsv), ichthyophonus hoferi, and hepatic and intestinal coccidians, was conducted from 2012 to 2016 in the nw atlantic ocean, new jersey, usa. neither vhsv nor i. hoferi was detected in any sample. goussia clupearum was found in the livers of 40 to 78% of adult herring in varying parasite loads; however, associated pathological changes were negligible. phylogenetic analysis based on small subunit 18s rr ...201627409233
in vitro leukocyte-encapsulation model in rainbow trout (oncorhynchus mykiss).we developed an in vitro model to study the cellular and molecular mechanisms of granulomatous inflammation in response to invading pathogens. ichthyophonus hoferi was used as a target for encapsulation by cultivated leukocytes from the kidney of the rainbow trout (oncorhynchus mykiss). the encapsulation process was observed over 1 week. the leukocytes were identified as either macrophages in the inner layer, or neutrophils and lymphocytes in the outer layer. the encapsulation response was inhib ...200818093653
assessing the accuracy of a polymerase chain reaction test for ichthyophonus hoferi in yukon river chinook salmon oncorhynchus tshawytscha.ichthyophonus hoferi plehn & mulsow, 1911, is a cosmopolitan, protistan pathogen of marine fishes. it is prevalent in mature returning chinook salmon oncorhynchus tshawytscha in the yukon river watershed, and may be associated with prespawning mortality. we developed and evaluated a polymerase chain reaction (pcr) test for i. hoferi using primers specific to the parasite's small subunit rdna. the test has a minimum detection limit of approximately 10(-5) parasite spores per reaction and does not ...200616532605
pathology and morphology of ichthyophonus hoferi in naturally infected fishes off the swedish west coast.the pathology and morphology of ichthyophonus hoferi was studied in naturally infected atlantic herring clupea harengus, in sprat sprattus sprattus, and in flounder pleuronectes flesus from the west coast of sweden. the pathogen was found in all organs examined, with the intensity of infection varying in different organs of the different fish species. two main phases in the life of infecting parasites were identified, 'active' and 'passive', the latter being able to switch to active. the active ...19989828406
pathogenicity of ichthyophonus hoferi for laboratory-reared pacific herring clupea pallasi and its early appearance in wild puget sound herring.laboratory-reared pathogen-free pacific herring were exposed to pure cultures of ichthyophonus hoferi, and reproduced the disease seen in naturally infected fish--thus fulfilling koch's postulates. pathogen-free herring used in this study were reared from artificially spawned eggs incubated in filtered, uv-sterilized seawater, eliminating the variables associated with multiple infections, which are common in wild herring. wild free-ranging herring were captured monthly from june through october ...199910073312
failure of population recovery in relation to disease in pacific herring.following an estimated 60% decline in population abundance in early 1993, recovery of the pacific herring clupea pallasii population of prince william sound, alaska, usa, has been impaired by disease. comprehensive epidemiological study from 1994 through 2002 validated an age-structured assessment (asa) model of disease and population abundance; from 2003 to 2006, the impact of disease was modeled by analyzing only 2 lesions: ulcers and white foci in the heart. the asa model identified increased ...201020597425
sequence analysis of the internal transcribed spacer (its) region reveals a novel clade of ichthyophonus sp. from rainbow trout.the mesomycetozoean parasite ichthyophonus hoferi is most commonly associated with marine fish hosts but also occurs in some components of the freshwater rainbow trout oncorhynchus mykiss aquaculture industry in idaho, usa. it is not certain how the parasite was introduced into rainbow trout culture, but it might have been associated with the historical practice of feeding raw, ground common carp cyprinus carpio that were caught by commercial fisherman. here, we report a major genetic division b ...201020402235
effect of viral hemorrhagic septicemia virus on pacific herring in prince william sound, alaska, from 1989 to 2005.we critically review the role of viral hemorrhagic septicemia virus (vhsv) in the 1992-1993 collapse of the prince william sound (pws) herring fishery. vhsv was detected in samples of moribund pacific herring from pws in spring 1993 when about 63% of the expected fish failed to appear. a low prevalence and severity of vhsv were observed in adult pre-spawning pws herring in most of the years from 1994 to 2002. the north american strain of vhsv became established about 500 yr ago in many northeast ...200919402455
transmission of the parasite ichthyophonus hoferi in cultured rainbow trout and comparison of epidemic models.the epidemic process of the parasite ichthyophonus hoferi in cultured rainbow trout oncorhynchus mykiss was quantitatively estimated by both the cohabitation experiment and two standard models (the kermarck-mckendrick model and the reed-frost model). for analysis of the parasite transmission by cohabitation, fish in two replicate tanks were exposed to 1, 5, or 10 infected fish, and daily mortality was counted for 102 d. despite simple experiments for artificial exposure to the pathogen, the dail ...200819306610
association of plasma igm with body size, histopathologic changes, and plasma chemistries in adult pacific herring clupea pallasi.pacific herring clupea pallasi immunoglobulin is an igm-like molecule comprised of heavy and light chains with molecular weights of 79 and 25 to 27 kd, respectively. purified immunoglobulin was used to generate highly specific polyclonal antibodies for development of a sandwich elisa. the elisa was used to quantify total plasma igm in 602 pacific herring captured in prince william sound and sitka sound, alaska, usa. plasma igm concentrations ranged from 0.13 to 5.32 mg ml-1. using multiple stepw ...199910598283
viral hemorrhagic septicemia virus, ichthyophonus hoferi, and other causes of morbidity in pacific herring clupea pallasi spawning in prince william sound, alaska, usa.pacific herring clupea pallasi populations in prince william sound, alaska, usa, declined from an estimated 9.8 x 10(7) kg in 1992 to 1.5 x 10(7) kg in 1994. to determine the role of disease in population decline, 233 pacific herring from prince william sound were subjected to complete necropsy during april 1994. the north american strain of viral hemorrhagic septicemia virus (vhsv) was isolated from 11 of 233 fish (4.7%). vhsv was significantly related to myocardial mineralization, hepatocellul ...19989676259
[occurrence of parasites, bacteria, viruses and fungi in fish that are pathogenic to men and fish].parasitological examinations comprised above 20,000 fish which were searched for parasitic nematoda of anisakidae. it was evidenced that herring were infected with anisakid larvae in 8%, cod and flatfish in 4% and the eelpouts in as many as in 52%. the species that prevails in these fish were: anisakis simplex, contracaecum osculatum c, hysterothylacium auctum and pseudoterranova decipiens, respectively. in direction of the bacteria pathogenic to man 765 fish were examined; in 38% there were fou ...19957571631
incorporating covariates into fisheries stock assessment models with application to pacific herring.we present a framework for evaluating the cause of fishery declines by integrating covariates into a fisheries stock assessment model. this allows the evaluation of fisheries' effects vs. natural and other human impacts. the analyses presented are based on integrating ecological science and statistics and form the basis for environmental decision-making advice. hypothesis tests are described to rank hypotheses and determine the size of a multiple covariate model. we extend recent developments in ...200818686586
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