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PubMed2004

Seasonal dynamics of Posthodiplostomum cuticola (Digenea, Diplostomatidae) metacercariae and parasite-enhanced growth of juvenile host fish.

The seasonal dynamics of Posthodiplostomum cuticola metacercariae in 0+ juvenile fish, Rutilus rutilus, Scardinius erythrophthalmus and Abramis bjoerkna, was studied on the floodplain of the Dyje River, Czech Republic. Prevalence and mean abundance of P. cuticola were significantly higher in R. rutilus than in S. erythrophthalmus or A. bjoerkna. A seasonal pattern of parasite infection with maximum values in autumn was evident in all three species. No effect of overwintering on the P. cuticola infection was detected. Parasite-induced growth was found for all three fish species investigated; the fish standard length and body weight of parasitized individuals were significantly higher than those of unparasitized fish from July to October. In April, no difference was found. The maximum enhanced growth of parasitized fish was found in months with low zooplankton densities, while the difference was lower when food was abundant.

Animals↗
PubMed2002

Biology of the schistosome genus Trichobilharzia.

Trichobilharzia is the largest genus within the family Schistosomatidae, covering over 40 species of avian parasites. To clarify the existing confusion in the systematics of the genus, we recommend combining knowledge of life cycles and developmental stages, snail/bird hosts, cytogenetical and molecular data together with morphological criteria for the characterization of particular species. The high specificity of Trichobilharzia for the intermediate host is a likely reflection of the ability to avoid the internal defence of specific snails. The spectrum of final hosts (birds) seems to be much wider. The infection of birds--trichobilharziasis--may lead to considerable tissue injuries, caused by eggs of the parasite or migration of immature/mature worms through the body. Most Trichobilharzia (visceral species) migrate through the viscera of the host, but nasal species display a neurotropic mode of migration. Due to a low specificity of penetrating cercariae, mammals (including humans) can be attacked. This leads to cercarial dermatitis, predominantly in sensitized hosts. Experimental infections indicate that Trichobilharzia never mature in an incompatible (mammalian) host. However, not all cercariae and schistosomula are necessarily trapped and eliminated in the skin, and parasites may migrate throughout the viscera and the nervous system of mammals. These findings suggest that the pathogenicity of Trichobilharzia may have been underestimated in the past and health risks associated with trichobilharziasis need to be studied further.

Animals↗
PubMed1992

Use of LANDSAT MSS imagery and soil type in a geographic information system to assess site-specific risk of fascioliasis on Red River Basin farms in Louisiana.

A geographic information system (GIS) was constructed in an ERDAS environment using maps of soil types from the USDA Soil Conservation Service, LANDSAT satellite multispectral scanner data (MSS), boundaries for 25 study farms, and slope and hydrologic features shown in a two-quadrangle (USGS, 7.5') area in the Red River Basin near Alexandria, Louisiana. Fecal sedimentation examinations were done in the fall of 1989, spring of 1990, and fall and winter of 1990-1991 on 10-16 random samples per herd. Fecal egg shedding rates for F. hepatica ranged from 10-100% prevalence and 0.3-21.7 eggs per two grams of feces (EP2G). For Paramphistomum spp., a rumen fluke also transmitted by F. bulimoides but not affected by flukicides, egg shedding rates ranged from 10-91% prevalence and 0.1-42.8 EP2G. Soil types present ranged from sandy loams to hydric, occasionally flooded clays. Herd Paramphistomum spp. egg shedding rates increased with the proportion of hydric clays present, adjusted for slope and major hydrologic features. F. hepatica infection intensity followed a similar trend, but were complicated by differing treatment practices. Results suggest that earth observation satellite data and soil maps can be used, with an existing climate forecast based on the Thornthwaite water budget, to develop a second generation model that accounts for both regional climate variation and site-specific differences in fascioliasis risk based on soils prone to snail habitat.

Animals↗
PubMed1993

Mucosal mast cell responses to experimental Metagonimus yokogawai infection in rats.

Intestinal mucosal mast cell (MMC) responses were studied in rats experimentally infected with Metagonimus yokogawai (Digenea: Heterophyidae). Twenty Sprague-Dawley rats were fed each 2,500 metacercariae isolated from the sweetfish and sacrificed on the week 1, 2, 3 and 4 post-infection (PI). Recovery of worms was performed from the small intestine of each rat. To visualize the MMCs, duodenal and jejunal (upper, middle and lower) tissue sections were made and stained with alcian blue/safranine-0. The average worm recovery rates were 16.2% and 13.8% on the week 1 and week 2, respectively, but they decreased rapidly to 4.1% and 4.2% on the week 3 and week 4 PI, respectively, which indicate spontaneous worm expulsion after the week 2. The MMC number in the infected rats was, compared with uninfected controls, significantly increased in the whole small intestine, through the whole period of observation. The peak level of mastocytosis was observed on the week 3 PI. It is strongly suggested that MMCs might be involved in the expulsion process of flukes from the rat intestine.

Animals↗
PubMed1985

[Pathogenesis of paramphistomiasis in sheep].

Experimental studies were carried out on the pathogenesis of Paramphistomum infection of 58 weaned lambs, aged 4 to 12 months, infected with various numbers of adolescaria. The test animals were divided into 5 groups, each group having 2 subgroups. Most of the animals were given the infectious material only once, while some of them were infected three times at 30-day intervals. The animals of the fifth group were infected with 5,000 live worms each. Adolescaria were obtained from experimentally infected snails of the Galba truncatula species. The changes taking place in both the test and the control animals were followed up, concerning the total protein, protein fractions, hemoglobin, red and white blood picture, and the hematocrit values. The changes in the level of Ca, P, and serum enzymes were also studied. The liver, spleen, kidneys, adrenals, periportal and mesenterial lymph nodes duodenum, and small intestine were sampled for histopathologic investigation, the cross-sectioned material being stained with hematoxylin-eosin and after Mallory (for the demonstration of hyalin). The PAS test was used to demonstrate glycogen. It was found that reconstructive changes took place in the infected animals as judged by the changes in the blood picture and the protein fractions, most substantial of which were those concerning the gamma-globulin fractions which rose almost twice by the 90th day. Microscopically, there were degenerative changes in the parenchymal organs, the duodenum, and the rumen as well as considerable reticulo-histiocytic proliferation and eosinophilic infiltration, with nonreactive necrotic foci in the rumen.

Animals↗
PubMedDate not supplied

[Change in the fish crystalline lens in experimental diplostomatosis].

Experimental infection of roach with cercariae of Diplostomum spathaceum has shown that the pentration of larvae into the eyeball proceeds in hematogenous way. Metacercariae are localized in the cortical layer of the crystalline lens thus causing destructive changes of its fibres and the dimness of the lens. The appearence of the dimness of the lens carries out without any apparent reactive changes in its epithelium. This enables to distinguish a parasitic cataract from all other varieties of cataracts.

Animals↗
PubMed2002

Impacts of diclidophorid monogenean infections on fisheries in Japan.

Many monogeneans are pathogenic to economically important fish in Japan. However no other monogenean is comparable with the diclidophorids, Heterobothrium okamotoi and Neoheterobothrium hirame, on the scale of impacts they inflict on Japanese fisheries. The shared importance of the two monogenean infections lies in their pathogenicity, fecundity and tolerance to chemical treatment. Heterobothrium okamotoi infects the gills and wall of the branchial cavity of the tiger puffer, Takifugu rubripes (Tetraodontidae), which is widely cultured in western Japan. The main presenting signs of infected fish are anaemia and extensive necrosis caused by adult worms. This monogenean deposits long strings of eggs, which reach lengths of almost 3 m. Egg entanglement with the mesh of culture nets increases the chance of hatched larvae encountering susceptible fish. The oncomiracidium maintains infectivity for up to 4 days after hatching. Hydrogen peroxide is the only commercially available chemical able to control the infection, but can only kill immature worms on the gills. Neoheterobothrium hirame infects the gills and wall of the buccal cavity of the Japanese flounder, Paralichthys olivaceus (Paralichthyidae). Since the first known occurrence of this monogenean in 1993, the species has been recorded from almost all areas where the host is distributed. Neoheterobothrium hirame has the potential to produce 781 eggs per day at 20 degree C. In the western Sea of Japan, wild young-of-the-year flounder became infected in early summer, followed by a sharp increase in prevalence in late summer. By late summer, juvenile flounder have nearly disappeared from the area, strongly suggesting that N. hirame is responsible for mortality of young fish. This is in good agreement with the recent decline in the local flounder population. Neoheterobothrium hirame has also been considered the causative agent of anaemia among wild Japanese flounder since the late 1990s.

Animals↗
PubMed1977

Experimental infection of cats with the liver fluke Platynosomum concinnum,.

The severity of Platynosomum concinnum infection in cats experimentally infected with 125 flukes (small dose) and 1,000 flukes (large dose) was determined by monitoring clinical signs and hematologic, serum biochemical, and pathologic changes during the infection. All cats (8/8) with a small fluke burden and 3 of 8 cats with a large burden remained clinically asymptomatic, whereas 60% of the cats given large doses had mild signs of inappetence and lethargy. Eosinophilia, peaking 4 to 5 months after infection, was present in all parasitized cats. During the early stages of platynosomiasis, a transient but substantial increase in aspartate aminotransferase and alanine aminotransferase activities was observed in cats given small and large doses. These observations agreed with gross and histopathologic observations, which included enlargement of the gallbladder and biliary ducts, with leukocyte infiltration, adenomatous hyperplasia, and fibrosis of the ductal areas.

Alanine Transaminase↗
PubMed1983

Transmammary infection of paratenic and definitive hosts with Alaria marcianae (trematoda) mesocercariae.

Transmammary infection with Alaria marcianae mesocercariae was demonstrated using mice as model, paratenic hosts. Prenatal transmission was ruled out because neonates removed immediately postpartum from infected dams were never infected. Mesocercarial distribution in virgin females and in females examined immediately postpartum showed no marked preference for the mammary glands. In contrast, infection of neonates that were allowed to suckle on infected dams was absolute, and the number of mesocercariae in the mammary glands of postparturient dams that suckled their young was increased significantly. These experimental observations were coupled with other observations on paratenic hosts to outline the pathways open to mesocercariae in gravid hosts. The term amphiparatenic host is coined for those host species that are paratenic hosts as adults, but as juveniles can serve as definitive hosts.

Animals↗
PubMed1995

Prevalence and transmission of cercariae causing schistosome dermatitis in Flathead Lake, Montana.

Numerous studies have been conducted on swimmer's itch, but very few have been in Montana and none on Flathead Lake, the largest, natural freshwater lake in the western United States. We conducted a study to determine the prevalence of hosts transmitting cercariae causing swimmer's itch in this lake. Hosts for this life cycle were determined by direct observation of fresh waterfowl fecal material for the presence of miracidia, and snails for the presence of cercariae. Swimmer's itch-producing cercariae were verified directly by placing various species on the arms of human volunteers and waiting for a reaction. Results of the study were further substantiated using a controlled experiment in which snails were individually infected with miracidia from the suspected waterfowl host and then checked for infection after a 6-wk incubation period. Our findings show that the common merganser (Mergus merganser) and the snail Stagnicola elrodi were natural hosts of the swimmer's itch parasite (Trichobiharzia ocellata) with prevalences of 84% and 2.0%, respectively. To our knowledge this is the first documented case of S. elrodi transmitting the swimmer's itch cercariae.

Animals↗
PubMed2002

Monogenea of Arabian Gulf fishes. 1. Descriptions of three Capsala spp. (Capsalidae) including Capsala naffari n. sp. infecting mackerel tuna Euthynnus affinis from coasts of Emirates.

Three species of the genus Capsala including Capsala naffari n. sp., C. neothunni (Yamaguti, 1968) and C. nozawae (Goto, 1894) are recorded and described from the buccal cavity of mackerel tuna Euthynnus affinis caught from Emirate coasts. Capsala naffari can be differentiated by its lateral spiniform teeth, which extend posteriorly, small measurements compared with the closely resembled C. gotoi and relatively large testes. This is the first record of the genus Capsala from Arabian Gulf fishes and E. affinis is a new host record.

Animals↗
PubMed2006

Determination of definitive and intermediate hosts of cercarial dermatitis-producing agents in northern Iran.

BACKGROUND: The study concerns the prevalence of avian schistosomes in intermediate and definite hosts in Mazandaran Province, northern Iran. METHODS: A total of 14190 fresh-water snails belonging to various genera were sampled and tested for cercarial emission by lighting and then crushing. During the same period, the nasal blood vessels and mesenteric veins of aquatic birds, mainly belonging to the Anatidae family, were examined under dissecting microscope for detecting adult worms. RESULTS: Forty-seven (0.33%) of examined snails mainly Lymnaea gedrosiana, L.palustris, L.stagnalis, and Planorbis planorbis were found to be infected with larval stages of Trichobilharzia spp. Adult schistosomes were observed in 25 (18.1%) wild waterfowls. The most infected birds were Anas platyrhynchos, A.clypeata, and Aythya ferina, respectively. CONCLUSION: Annually migration of various species of aquatic birds toward the northern parts of Iran and the simultaneous presence of intermediate snails in the water resources of this area, combined with long hours of sunshine in the summer months, suggest that cercarial dermatitis could be a prominent health problem, especially among paddy field workers in this area.

Animals↗
PubMed1993

Buticulotrema stenauchenus n. gen., n. sp. (Digenea: Opecoelidae) from Malacocephalus occidentalis and Nezumia aequalis (Macrouridae) from the Gulf of Mexico.

Buticulotrema stenauchenus n. gen., n. sp. (Opecoelidae: Opecoelinae) is described from the macrourid fishes Malacocephalus occidentalis Goode and Bean, 1885, and Nezumia aequalis Günther, 1878, collected in June 1971 from the DeSoto Canyon area of the Gulf of Mexico at a depth of 495 m. Eight of 25 (32%) M. occidentalis and 1 of 8 (13%) N. aequalis examined were infected with the new opecoelid. Specimens of Bathygadus macrops Goode and Bean, 1886, and Coelorhynchus coelorhynchus Risso, 1810, collected at the same time were not infected with B. stenauchenus. The new genus most closely resembles Genitocotyle Park, 1937, but differs in that it lacks an accessory sucker behind the genital pore, contains a blind rather than canalicular seminal receptacle, and has a slightly pedunculate acetabulum, a pharynx that is longer than wide, and a distinctive, long-necked, bottle-shaped body. Buticulotrema stenauchenus is also similar to Pseudopecoelus von Wicklen, 1946, but the latter lacks a blind seminal receptacle.

Animals↗
PubMed1990

Single- and five-worm infections of Echinostoma caproni (Trematoda) in the ICR mouse.

Twenty-nine (64%) of 44 ICR mice fed a single metacercarial cyst of Echinostoma caproni and all of 23 mice each fed five cysts were infected with ovigerous worms at necropsy 2-4 weeks post-infection. Each host fed five cysts had two to five worms at necropsy, and all worms were either paired or clustered. Distribution of worms in the small intestine was similar in single- and five-worm infections and all worms were located 17-20 cm anterior to the ileo-cecal valve. Both single and multiple worms produced eggs with fully-developed miracidia. The number of eggs per uterus in 2-week-old multiple worms was almost twice that of single worms. The body area of 3- and 4-week-old multiple worms was significantly greater than that of single worms of the same age.

Animals↗
PubMed1993

Parvatrema timondavidi (Digenea; Gymnophallidae) transmitted by a clam, Tapes philippinarum, in Korea.

Metacercariae of Parvatrema timondavidi (Digenea; Gymnophallidae) were found from Tapes philippinarum, one of the most common marine clams in Korea. T. philippinarum was collected from a fishery market in Seoul, and all of the clams examined were found to contain many gymnophallid metacercariae. To get adult worms, 10 ICR mice were fed with 100 metacercariae each and sacrificed by cervical dislocation at 7, 10 and 14 days after the infection. The adult worms harvested from the intestinal contents of the mice were morphologically characterized by oval body shape, large oral sucker with lateral projections on the lip, absence of the ventral pit, single cluster of vitellaria, and separately located genital pore from the ventral sucker. Based on these characters they identified as P. timondavidi Bartoli, 1964. This study first confirms the presence of P. timondavidi metacercariae in T. philippinarum in Korea.

Animals↗
PubMed2001

Intestinal heterophyidiasis: an emerging food-borne parasitic zoonosis in southern Philippines.

Heterophyidiasis is an infection of the small bowel by minute intestinal flukes of the genus Heterophyes or related members of the family Heterophyidae. To provide a better understanding of this rarely reported condition, this study attempted to determine the infection rate, intensity of infection as well as the clinical spectrum of heterophyid infection. A stool survey was conducted in barangay San Isidro, Monkayo, Compostela Valley. Thirty-six percent of patients with history of bowel disturbance (abdominal discomfort/pain and/or diarrhea) in the past 4 weeks were found to have heterophyidiasis. All age groups were infected, with the youngest patient being 1 year 7 months of age, while the oldest patient was 73 years of age. Prevalence was highest in the 15 to 30 years old group at 55.3%. The most common clinical manifestations of heterophyidiasis were signs and symptoms of acid peptic or peptic ulcer disease. Early diagnosis and treatment are important to ensure prompt resolution of heterophyid infection, hence, decreased morbidity and decreased chances for complications like heart or brain involvement. Proficiency of laboratory staff should be enhanced to ensure accurate diagnosis which will then make appropriate treatment possible.

Adolescent↗
PubMed2006

Heterogeneous interspecific interactions in a host-parasite system.

Macroparasites of vertebrates usually occur in multi-species communities, producing infections whose outcome in individual hosts or host populations may depend on the dynamics of interactions amongst the different component species. Within a single co-infection, competition can occur between conspecific and heterospecific parasite individuals, either directly or via the host's physiological and immune responses. We studied a natural single-host, multi-parasite model infection system (polystomes in the anuran Xenopus laevis victorianus) in which the parasite species show total interspecific competitive exclusion as adults in host individuals. Multi-species infection experiments indicated that competitive outcomes were dependent on infection species composition and strongly influenced by the intraspecific genetic identity of the interacting organisms. Our results also demonstrate the special importance of temporal heterogeneity (the sequence of infection by different species) in competition and co-existence between parasite species and predict that developmental plasticity in inferior competitors, and the induction of species-specific host resistance, will partition the within-host-individual habitat over time. We emphasise that such local (within-host) context-dependent processes are likely to be a fundamental determinant of population dynamics in multi-species parasite assemblages.

Animals↗
PubMed1986

The epidemiology of diplostomiasis in farmed rainbow trout from north-east Scotland.

An epidemiological survey of the distribution and abundance of Diplostomum spathaceum in farmed rainbow trout (Salmo gairdneri) from Mill of Cantray trout farm (Nairn, Morayshire) involved monthly sampling of fish over a 3-year period. Diplostomum metacercariae were present in both the lens and aqueous humour of infected fish, and these have been treated separately throughout the study. The infection period was normally between May and September each year and transmission of the parasite from snail to fish did not occur at temperatures below 10 degrees C. The prevalence and abundance of both lens and humour metacercariae reached a maximum in September. The cleansing and application of a molluscicide (copper sulphate) to the raceways in spring resulted in a 56% reduction in the numbers of metacercariae infecting trout during the following summer. However, no further improvement in parasite control was recorded when the treatment was repeated in the following year. Experiments using caged fish indicated that diplostomiasis was confined to certain areas of the farm only and that the infection rate of rainbow trout with D. spathaceum cercariae was correlated (P less than 0.01) with water temperature. The results of the study indicated that it is possible by regular cleaning and use of molluscicides to keep the intensity of diplostomiasis at such a level that rainbow trout do not become severely affected. However, as with other parasitic diseases, a combination of control methods will probably be required to eradicate the disease completely from trout farms.

Animals↗