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PubMed2006

Radioresistance of Anisakis simplex third-stage larvae and the possible role of superoxide dismutase.

The radioresistance of Anisakis simplex third-stage larvae and the possible role of sublethal radiation on superoxide dismutase (SOD) were investigated. Larvae were isolated from the viscera of the sea eel Anago anago; irradiated with 10, 100, 200, 500, or 1,000 Gy; and then given orally to rats. Worms were recovered at 16 hr postinoculation. Most larvae were found to have invaded the gastric wall, omentum, and abdominal cavity, suggesting that their viability and infectivity were not controlled by irradiation with the doses used. To determine the relationship between SOD activities in parasites and their radiosensitivities, the larvae of A. simplex and the metacercariae of Neodiplostomum seoulense (a radiosensitive control) were irradiated with 0, 30, 100, or 500 Gy, and parasite SOD levels were measured. In nonirradiated A. simplex larvae, the average SOD level was 38.9 U/mg, and this increased to 51.3 U/mg at 500 Gy. However, at all radiation doses applied, SOD activities of N. seoulense metacercariae were significantly (P < 0.05) lower than those of A. simplex larvae. Our results demonstrate that A. simplex third-stage larvae are radioresistant, and suggest that SOD plays a role in this radioresistance.

Animals↗
PubMed1984

Pathway of mesocercariae of Alaria marcianae (Trematoda) through the mammary glands of lactating mice.

Lactating mice were infected with mesocercariae of Alaria marcianae to demonstrate more precisely how these parasites migrate within the mammary glands. The infected dam that first transmitted larvae to all of her young was necropsied and her mammary glands removed and sectioned serially. Mesocercariae penetrated the dense connective tissue surrounding the lobules. Within the stroma the larvae migrated along tracks of fat cells and were consistently found in pools of milk created from the destruction of alveoli. These pools of milk led directly into the large lactiferous ducts. It was notable that no mesocercaria was found in the lactiferous or galactiferous ducts indicating that clearance from these vessels was rapid. No larva was found in any blood vessel nor was any significant hemorrhage demonstrable. Lack of an inflammatory response surrounding the worm was characteristic, although large numbers of neutrophils were scattered diffusely throughout the lobules, and multiple, proliferative lymph nodules were present.

Adipose Tissue↗
PubMed2006

A loss of fecundity in a population of mudsnails Hydrobia ventrosa caused by larval trematodes does not measurably affect host population equilibrium level.

Host snail demography and trematode parasitism were followed for one host generation in a shallow brackish lagoon of the western Baltic Sea. In addition, a laboratory experiment was simultaneously conducted to quantify the effects of parasitic infection on host fecundity. Hydrobia ventrosa of the cohort of 1996 had a maximum life-span of up to 2 years and reproduced between May and November of their second calendar year in 1997. Snails died after reproduction. The first trematode infections appeared in May 1997 when the snails started to mature. Total trematode prevalence peaked in summer and declined during winter to the lowest level in early spring 1998. Eight taxa of larval trematodes were found. Egg production of females with trematode infections was significantly reduced. Among females with pre-patent infections, about 20% were still able to produce eggs. Among females with patent infections merely 9% could lay eggs, compared to an average of about 51% in uninfected females. Taking into account a summer prevalence of about 25%, parasitic infections caused an overall reduction in egg production of the snail host population of about 15%. The reduction in host fecundity as a result of larval trematode infection did not measurably affect the population dynamics of H. ventrosa, because other environmental factors, especially winter severity and available food supply, were concluded to be much more relevant.

Animals↗
PubMed2000

Surface morphology of Probolocoryphe uca (Sarkisian, 1957) (Digenea: Microphallidae) from Kuwait bay.

The surface ultrastructure of Probolocoryphe uca (Digenea: Microphallidae), recovered from a rat experimentally fed on crabs, Nanosesarma minutum (Brachyura: Grapsidae), naturally infected with the metacercariae, was studied by scanning electron microscopy. The flukes were leaf-like, ventrally concave and pyriform or ovoid in outline. The anterior end was modified into a sucker-like organ, comprising a protrusible disc-shaped structure surrounded by single-pointed spines. This organ is probably involved in the attachment and feeding process in a manner similar to the action of the oral suckers. Apart from the sucker-like organ, the entire tegumental surface was covered with triangular spines with multi-pointed tips. Ciliated, dome-shaped papillae were observed, singly or in groups, arranged symmetrically on the sucker-like organ and around the oral and ventral suckers. Kuwait Bay constitutes a new geographical record and the crab N. minutum is a new second intermediate host record for P. uca.

Animals↗
PubMed2006

Morphological, developmental and ecological evidence for a progenetic life cycle in Neochasmus (Digenea).

Seven species of fishes, Catostomus commersonii (Lacépède), Etheostoma nigrum Rafinesque, Micropterus dolomieu Lacépède, Notemigonus crysoleucas (Mitchill), Notropis hudsonius (Clinton), Perca flavescens (Mitchill), and Percina caprodes (Rafinesque) from the St. Lawrence River, Quebec, Canada, were found infected with progenetic specimens of Neochasmus spp. in the orbits and/or the body musculature. Worms displayed varying degrees of maturation. Eggs occupied the entirety of the worm in late stages of development and persisted as distinct clusters in situ after worm death. Populations of parasites were studied monthly in E. nigrum from one site between May and October in order to follow parasite recruitment, development and maturation. Recruitment of parasites was observed in young-of-the-year fish primarily in July and continued through October. Worms matured rapidly, displaying egg production within a month. Later developmental stages, in which eggs occupied most of the worm, and clusters of eggs became abundant by September. Infections in overwintered fish collected in May consisted mainly of worms in early stages of egg production and of clusters of eggs. When hatched artificially, eggs from the clusters released viable miracidia, indicating that they survive beyond the lifespan of the adult worm. It is suggested that progenesis is a fixed characteristic of the life cycle of these species, that egg dispersal requires the death of the host and that it is facilitated by predation. All prior records of Neochasmus spp. are examined, leading us to conclude that the role of the putative definitive host (primarily basses) has been reduced to that of a dispersal agent. Current hypotheses concerning the evolution and maintenance of progenesis are considered, but it is concluded that they do not apply to this host-parasite system.

Animals↗
PubMed2006

Identification of genetic markers associated with Gyrodactylus salaris resistance in Atlantic salmon Salmo salar.

Gyrodactylus salaris Malmberg, 1957 is a freshwater monogenean ectoparasite of salmonids, first recorded in Norway in 1975 and responsible for extensive epizootics in wild Atlantic salmon Salmo salar L. The susceptibility of different populations of Atlantic salmon to G. salaris infection differs markedly, with fish from the Baltic being characterised as relatively resistant whereas those from Norway or Scotland are known to be (extremely) susceptible. Resistance to Gyrodactylus infection in salmonids has been found to be heritable and a polygenic mechanism of control has been hypothesised. The current study utilises a 'Quantitative trait loci' (QTL) screening approach in order to identify molecular markers linked to QTL influencing G. salaris resistance in B1 backcrosses of Baltic and Scottish salmon. Infection patterns in these fish exhibited 3 distinct types; susceptible (exponential parasite growth), responding (parasite load builds before dropping) and resistant (parasite load never increases). B1 backcross fish were screened at 39 microsatellite markers and single marker-trait associations were examined using general linear modelling. We identified 10 genomic regions associated with heterogeneity in both innate and acquired resistance, explaining up to 27.3% of the total variation in parasite loads. We found that both innate and acquired parasite resistance in Atlantic salmon are under polygenic control, and that salmon would be well suited to a selection programme designed to quickly increase resistance to G. salaris in wild or farmed stocks.

Animals↗
PubMed1999

[Experimental therapy of Pagumogonimus skrjabini infection in rats with triclabendazole].

AIM: To observe the therapeutic effect of triclabendazole in rats infected with Pagumogonimus skrjabini. METHODS: Metacercariae of P. skrjabini were isolated from crabs (Sinopotamon) collected from two endemic areas (Weiyuan County of Sichuan Province and Wansheng District of Chongqing Municipality). Wistar rats were each infected intraperitoneally with metacercariae. One month and two months after infection, the infected rats were treated with triclabendazole at the total dosage of 300 mg/kg over 2 days, 450 mg/kg over 3 days and 600 mg/kg over 3 days, respectively. RESULTS: The worm reduction rates were 50%, 80% and 87% respectively one month after completion of tretment. Dead worms (about 1 mm size) recovered from the muscles, liver, abdominal cavity, chest cavity and lungs were signicantly diminished in size and weight in comparison with those of the control group. Many large (about 1 cm) black-colored distended worm cysts usually with two adult worms and many eggs were found in the lungs of the control rats. Most worm cysts in the treated groups of rats were found to be atrophied, changing into hemorrhagic-necrotic patches. CONCLUSION: Triclabendazole is highly active against P. skrjabini in rats.

Animals↗
PubMed1984

Histopathology of the duodenum and rumen of goats during experimental infections with Paramphistomum cervi.

On microscopic examination after experimental infection with Paramphistomum cervi, tissue reactions in the duodenum were more pronounced during early stages of the infection (20th day post-infection (DPI)). Immature parasites were seen migrating to the muscularis layer, and focal infiltration of macrophages and lymphocytes was observed in the lamina propria and in the interstitial tissue of Brunner's gland. At places, there was cystic dilatation of Brunner's gland. At 40 DPI, the parasite was not present in the duodenal sections, and cellular infiltration was more diffuse and consistent. With the passage of time, the tissue reactions and cellular infiltration in the duodenum became less pronounced, but at 80 days parasites were attached to the villi of the rumen. Infiltration of mononuclear cells in the supporting connective tissue of the rumen was also observed. Thus, it is concluded that the immature forms of Paramphistomum cervi caused more severe damage in the duodenal tissue, whereas the adult form inflicted mild tissue damage in the rumen of the experimental kids.

Animals↗
PubMed1989

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster.

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 +/- 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80 degrees C) alcohol-formalin-acetic acid was 0.21 mm2 on day 3, 4.9 mm2 on day 10, and 17.7 mm2 on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.

Animals↗
PubMed2004

Description of Brachylecithum mackoi n. sp. (Digenea: Dicrocoeliidae) from the European hedgehog, Erinaceus europaeus (Insectivora: Erinaceidae).

A new hepatic dicrocoeliid species, Brachylecithum mackoi n. sp. (Digenea, Dicrocoeliidae), is described from the European hedgehog, Erinaceus europaeus (L.) (Insectivora, Erinaceidae). An infected host was found in the Mediterranean island of Elba (Italy), and more than 60 individuals were isolated from the biliary ducts. The holotype and 55 paratypes were examined. Brachylecithum mackoi n. sp. differs from congeneric species found in mammal hosts by having well-developed lappets in the ventral sucker, a sloping uterus between anterior testis and acetabulum, no overlap between vitellaria, and metrical features in the body size, sucker diameters, cirrus sac, and size of eggs. The only other Brachylecithum species of erinaceids in Europe and Africa, Brachylecithum aetechini Dollfus, 1951, differs from the new species in the above-mentioned morphological characters, greater dimensions of the body, and oral sucker, pharynx, cirrus sac, and egg dimensions. The presence of B. mackoi n. sp. in Elba Island is discussed in the light of apparent host specificity of erinaceid dicrocoeliids and geographical distribution of Palearctic and Ethiopian Erinaceidae.

Animals↗
PubMed1998

Pathogenicity and lethality of a minute intestinal fluke, Neodiplostomum seoulense, to various strains of mice.

Pathogenicity and lethality of Neodiplostomum seoulense to various strains of mice (mast cell-deficient W/Wv, their normal littermate +/+, C57BL/6, BALB/cA, C3H/HeJ), and a hybrid (BALB/cA x C3H/HeJ)F1 were investigated. When the mice were infected orally each with 200 metacercariae, their abdomen became distended, and all mice died by day 23 postinfection (PI) except BALB/cA, which were severely weakened but recovered after 28 days. Even a smaller infection dose of 25 metacercariae was highly lethal to C3H/HeJ mice. Despite treatment with praziquantel (3 mg/mouse) on day 10 PI, 80% of C57BL/ 6 mice did not recover and died. After day 14 PI, the whole intestine of C57BL/6 mice was contracted and significantly shortened in length, and charcoal meal transit was significantly faster compared with uninfected controls. After incubation in papaverine, the contracted intestines of C3H/HeJ mice did not relax, suggesting that the change is irreversible. In conclusion, N. seoulense has the potential to kill most strains of mice by causing irreversible damage to their intestine. The effects of mucosal mast cells on the survival rate of mice were negligible, because both W/Wv and +/+ mice died around day 20 PI.

Animals↗
PubMed1997

Paramphistomum daubneyi: the development of redial generations in the snail Lymnaea truncatula.

Rediae of Paramphistomum daubneyi were counted and measured in Lymnaea truncatula to elucidate the variability in the numbers of free rediae and cercariae occurring between naturally infected snails and experimental single-miracidium infections. Experiments were performed using one miracidium per snail and snail raising was carried out at 20 degrees C. Two redial generations succeeded each other in the snail until day 49. A mean of 8-10 rediae differentiated in the sporocyst at days 7 and 14; the remaining germ balls and redial embryos decreased in number after day 21. First-generation rediae became free in the snail's body starting at day 14 and their number increased to a mean of 7.5 at day 49, with a maximum of 10 rediae being detected in 1 snail. They produced second-generation rediae, which exited from the body starting at day 28, and then cercariae, which exited from day 42 onward. The count of second-generation rediae was 6-6.2/snail at day 49, with a maximum of 12 being detected in 1 snail; they produced only cercariae.

Animals↗
PubMedDate not supplied

[Methods for studying the distribution of Monogenea in the gills of fishes].

The infection rate with monogeneans of different sites of fish gills was examined. The comparative analysis of average parts (in %) was made after [see text] Fisher where phi is a percentage in radians, n -- the number of fishes dissected, v -- degrees of freedom. It was shown statistically, that part (%) of dactylogyrids on II paris of the gills is significantly greater than parts from I and III pairs of the gills. The parts of the parasites were not distinguished on I and III pairs of the gills. The part of worms on IV pair of the gills is the least. It was shown that statistically significant part of the dactylogyrids was observed in the middle sector of the gills. Factors, which could led to unequal distribution of monogeneans on the gills, are discussed. The main factor appears to be a volume of water stream passing through different pairs of the gills.

Animals↗
PubMed1990

The subcutaneous attachment of the monogenean Heterobothrium elongatum (Diclidophoridae) in the gills of Torquigener pleurogramma (Pisces: Tetraodontidae).

Heterobothrium elongatum predominantly occurred on the most anterior pair of gill arches of infected pufferfish, Torquigener pleurogramma. Juvenile and immature stages attached to gill lamellae and were concentrated on the ventral regions of the anterior pair of gill arches. Following penetration of subcutaneous tissues, young adult worms formed a subcutaneous channel either directly above or below the transverse septum, a tissue layer connecting the bases of adjacent gill rays. Large, sexually mature worms extended for most or all of the length of the gill arch where they filled the area normally occupied by the longitudinal lymphatic vessel (branchial vein) or lay adjacent to the efferent branchial and colateral arteries. Subcutaneous attachment by the parasite induced a marked inflammatory reaction in the host. During growth, the mid-region of the parasite became markedly elongate and formed a stalk connecting the haptor lying in the dorsal region of the gill and the body which emerged from the lower margin of the gill where penetration began.

Animals↗
PubMed2005

Intestinal distribution and fecundity of two species of Diplostomum parasites in definitive hosts.

This paper investigated the intestinal distribution and fecundity of 2 species of Diplostomum parasites, D. spathaceum and D. pseudospathaceum, in 2 species of definitive hosts, herring gull (Larus argentatus) and common gull (L. canus), using both empirical field data and experimental infections. At the level of individual hosts, the parasite species occupied different parts within the intestine, but the fecundity of the worms, measured as the number of eggs in the uterus, did not differ between the parasite species except in wild common gulls. Interestingly, egg numbers in individual hosts were positively correlated between the parasite species suggesting that some birds provided better resources for the parasite species. At the host population level, fecundity of the worms did not differ between the host species or between adult birds and chicks. Both parasite species were also aggregated to the same host individuals and it is likely that aggregation is transferred to gulls from fish intermediate hosts. Individual differences in suitability and parasite numbers between hosts provide important grounds and implications for epidemiological model-based parasite prevention strategies.

Animals↗
PubMed2003

Role of intestinal goblet cells in the expulsion of Gymnophalloides seoi from mice.

Role of intestinal goblet cells (GCs) in the expulsion of Gymnophalloides seoi was studied using 4 strains of mice, ICR, C3H/ HeN, BALB/c, and C57BL/6, after infection with 200 metacercariae isolated from oysters. On day 7 postinfection (PI), significantly higher (P < 0.05) worm recovery rates (WRRs) were observed in ICR (29.5 +/- 12.0%) and C3H/HeN (14.8 +/- 8.2%) than in BALB/c (5.7 +/- 5.3%) and C57BL/6 (0.8 +/- 1.1%) mice. Alteration of the GC mucins was marked in C57BL/6 mice. On day 14 PI, 5.2 +/- 5.2% and 0.6 +/- 0.7% of worms were recovered only from ICR and C3H/HeN mice. When C57BL/6 mice were immunosuppressed with prednisolone, WRR on day 7 PI increased to 11.7 +/- 13.9%, whereas the GC hyperplasia and mucin alteration diminished significantly. The results suggest that expulsion of G. seoi from the intestine is dependent on immune responses of the host, and GCs may be an important effector.

Animals↗
PubMed1981

Paramphistomum microbothrioides in American bison and domestic beef cattle.

Intestinal paramphistomiosis was diagnosed in a bull and cow with severe diarrhea and weight loss, and subsequent investigation suggested that the infection was transmitted from American bison (Bison bison). The rumen fluke, Paramphistomum microbothrioides, was recovered from the rumen of 3 bison on the farm or origin. Single operculate eggs of P microbothrioides measuring 130 x 69 micrometers were recovered from the feces of the bull, from 9 of 10 bison, and from 3 of 9 other beef cattle. Snails of the genera Physa and Helisoma were collected at the farm of origin. Ostertagiosis and paratuberculosis were considered in the differential diagnosis but were ruled out on the basis of fecal, plasma, and mucosal tests. In view of the lack of approved drugs for treatment of paramphistomes in the United States, treatment was attempted with an 8 times normal dose of thiabendazole (528 mg/kg). Advice was given on grazing management strategies designed to reduce exposure of susceptible cattle to metacercariae, and the owner was advised to drain a large snail habitat.

Animals↗
PubMedDate not supplied

[Evaluation of chemotherapeutic agents against cichlidogyriasis in tilapia (Oreochromis hornorum) in Mexico].

To evaluate the efficacy of seven compounds against the cichlidogyriasis of tilapia fish (Oreochromis hornorum), two experiments were carried out. In one, 160 naturally infected fish with a mean burden of 33.4 parasites/animal were used. In another, 1600 fish with a burden of 49.9 parasites/fish were used. Fish were randomly divided into eight equal groups and received three treatments as submersion baths: methylene blue, malachite green, potassium permanganate, sodium chloride, formaldehyde, copper sulfate and triclorfon, and a non-treated control. Five days after the last treatment, all fish were killed and dissected to quantify the remaining parasites. All data were submitted to an ANOVA analysis. All groups compared to the control showed statistical difference (P < 0.01), with better efficacy at higher doses. Sodium chloride, potassium permanganate and triclorfon are highly efficient in the control of cichlidogyriasis of tilapia fish, but care should be taken with the toxicity of the two first compounds.

Animals↗