Xiphidiocercariae from naturally infected Lymnaea columella (Mollusca, Gastropoda) in urban area: morphology and ultrastructure of the larvae and histological changes in the mollusc host / Xifidiocercárias obtidas em Lymnaea columella (Mollusca, Gastropoda) naturalmente infectadas em área urbana: morfologia e ultraestrutura da larva e alterações histológicas do molusco hospedeiro

Abstract Urban agriculture is very common in the cities, as Rio de Janeiro and adjacencies, being important as economic activity. However, this practice can create appropriate conditions for establishment and maintenance of life cycle of many parasites. Lymneid snails can act as intermediate hosts of many trematodes species, including those that infect humans and wild and domestic. In the present study, the snail Lymnaea columella was collected from an urban watercress plantations and the morphology of cercariae released by them was analyzed by light and scanning electron microscopy. The specimens were identified as xiphidiocercariae, belonging to the Cercariae Ornatae group, of the order Plagiorchiiformes. Histological examination of the digestive gland of the infected snails revealed the presence of developing sporocysts, with hemocitary infiltration and metaplasia in the epithelial tissue.

Resumo Agricultura urbana é muito comum nas cidades, como Rio de Janeiro e adjacências, sendo uma importante atividade econômica de subsistência. No entanto, esta prática pode criar condições adequadas para o estabelecimento e manutenção do ciclo de vida de muitos parasitos. Os moluscos limneídeos podem atuar como hospedeiros intermédios de muitas espécies de trematódeos, incluindo aqueles que infectam humanos e animais selvagens e domésticos. No presente estudo, o molusco Lymnaea columella foi coletado de plantações urbanas de agrião e a morfologia das cercárias liberadas por eles foi analisada por microscopia eletrônica de varredura leve e de varredura. As larvas foram identificadas como xifidiocercárias, pertencentes ao grupo das Cercariae Ornatae, Ordem Plagiorchiiformes. Análises histológicas da glândula digestiva dos moluscos infectados evidenciaram esporocistos, com formação de granuloma e metaplasia do tecido epitelial.

Larvas de trematódeos em moluscos do Brasil: panorama e perspectivas após um século de estudos / Larval trematodes in molluscs of Brazil: overview and perspectives after a century of studies

O estudo de larvas de trematódeos encontradas em moluscos no Brasil foi iniciado há cerca de um século e, desde então, dezenas de cercárias e alguns ciclos biológicos destes parasitos foram descritos no país. Na presente atualização, são discutidos aspectos relacionados ao diagnóstico diferencial entre as cercárias de espécies de importância médico-veterinária, como Schistosoma mansoni e Fasciola hepatica, e outras larvas de parasitos de animais silvestres. Uma chave de identificação dos principais tipos cercarianos e suas características biológicas gerais são apresentadas. Além disso, são discutidos os estudos destes parasitos com enfoque em biodiversidade, biologia evolutiva e ecologia, bem como sua possível utilização como bioindicadores e controladores biológicos, abordagens pouco utilizadas no Brasil...

Depressed Neuronal Growth Associated Protein (GAP)-43 Expression in the Small Intestines of Mice Experimentally Infected with Neodiplostomum seoulense

Neodiplostomum seoulense (Digenea: Neodiplostomidae) is an intestinal trematode that can cause severe mucosal pathology in the small intestines of mice and even mortality of the infected mice within 28 days after infection. We observed neuronal growth associated protein-43 (GAP-43) expression in the myenteric plexus of the small intestinal wall of N. seoulense-infected mice until day 35 post-infection (PI). BALB/c mice were infected with 200 or 500 N. seoulense metacercariae isolated from naturally infected snakes and were killed every 7 days for immunohistochemical demonstration of GAP-43 in the small intestines. N. seoulense-infected mice showed remarkable dilatation of intestinal loops compared with control mice through days 7-28 PI. Conversely, GAP-43 expression in the mucosal myenteric plexus was markedly (P<0.05) reduced in the small intestines of N. seoulense-infected mice during days 7-28 PI and was slightly normalized at day 35 PI. From this study, it is evident that neuronal damage occurs in the intestinal mucosa of N. seoulense-infected mice. However, the correlation between intestinal pathology, including the loop dilatation, and depressed GAP-43 expression remains to be elucidated.

In Vitro Cultivation of Cymatocarpus solearis (Brachycoeliidae) Metacercariae to Obtain the Adult Stage without the Marine Turtle Definitive Host

In vitro cultivation of trematodes would assist studies on the basic biology of the parasites and their hosts. This is the first study to use the yolk of unfertilized chicken eggs as a simple and successful method of ovocultivation and the first time to obtain the adult-stage of the trematode Cymatocarpus solearis Braun, 1899 (Digenea: Brachycoeliidae). Chicken eggs were inoculated with metacercariae from the muscle of the spiny lobster, Panulirus argus (Latreille, 1804). The metacercariae were excysted and incubated for 576 hr (24 days) at 38degrees C to obtain the adult stage. Eggs in utero were normal in shape and light brown color. The metacercariae developed into mature parasites that have been identified as the adult-stage found in marine turtles. The adult lobsters collected in Quintana Roo State, Mexico, showed the prevalence of 49.4% and the mean intensity of 26.0 per host (n = 87). A statistical study was performed to determine that no parasitic preference was detected for male versus female parasitized lobsters. Morphometric measurements of the adult-stage of C. solearis obtained in our study have been deposited in the National Helminths Collection of the Institute of Biology of the National Autonomous University of Mexico. This study is significant because it is the first time that a digenean of the family Brachycoeliidae has been demonstrated to develop in vitro from metacercariae into adults capable of producing eggs using the yolk of unfertilized chicken eggs. Secondly, this technique allows to obtain the adult stage of C. solearis without the presence of its marine turtle host, allows us to describe the mature parasites, and thus contribute to our understanding of the biology of C. solearis.

Comunidad de Monogenea en las branquias de Pimelodus albicans (Valenciennes, 1840) en el río Salado del Norte, San Justo (Santa Fe, Argentina) / Monogenea community on the gills of Pimelodus albicans (Valenciennes, 1840) in the northern salado river, San Justo (Santa Fe, Argentina)

Se estudió la comunidad de Monogenea de las branquias de juveniles de Pimelodus albicans Valenciennes 1840, en el río Salado del Norte, tributario del río Paraná Medio (Argentina). Se hallaron los siguientes taxa: Demidospermus armostus, Demidospermus bidiverticulatum, Demidospermus idolus, Demidospermus majusculus, Scleroductus yuncensi, Demidospermus sp y Ancyrocephalinae sp. Los resultados permiten concluir que no existe una especie dominante, aunque D. majusculus, D. armostus, D. idolus y Ancyrocephalinae sp se destacan por ser secundarias. La diversidad parasitaria local es moderada y no existe correlación entre la talla de los hospedadores y la intensidad de infestación de todos los taxa. En este artículo se analizan las infrapoblaciones e infracomunidades de Monogenea de P. albicans, y se presenta un nuevo registro de distribución geográfica de estos ictioparásitos neotropicales.

It was studied the monogenean communities on the gills of a Pimelodus albicans Valenciennes, 1840 juvenile, in the Northern Salado River, tributary of the Middle Paranß River (Argentina). Monogenea taxa were found: Demidospermus armostus, Demidospermus bidiverticulatum, Demidospermus idolus, Demidospermus majusculus, Scleroductus yuncensi, Demidospermus sp and Ancyrocephalinae sp. The results allow us to conclude that: D. majusculus, D. armostus, D. idolus and Ancyrocephalinae sp were secondary species and there is no a dominant one. The local diversity of parasites is moderate and there is no correlation between the size of the hosts and the intensity of parasitism. In this article, the infrapopulations and infracommunities of monogenean of P. albicans, were analyzed. These reports show a new geographical distribution register ofneotropical monogenean species.

Survey for zoonotic liver and intestinal trematode metacercariae in cultured and wild fish in An Giang Province, Vietnam

Although Vietnam has a high risk of fishborne zoonotic trematode (FZT) infections for humans, little information exists on the epidemiology of these infections in the country's fish. Because of the importance of cultured catfish and snakehead production in An Giang province, a major production area in the Mekong Delta of Vietnam, a survey for FZTs was carried out in randomly selected fish farms between June 2005 and March 2006. For comparison, wild fish from the same area were also surveyed. A total of 852 cultured fish from 4 districts were collected and examined by pepsin digestion to determine their FZT infection status. In Tra catfish, the prevalence of all types of metacercariae was 2.6%, of which the prevalence of Haplorchis pumilio was 0.7%. The overall prevalence of metacercariae in wild fish was 30.6%, of which 10.3% harbored zoonotic species: H. pumilio (2.8%) and Procerovum sp. (5.6%). The prevalence of Opisthorchis metacercariae, which were diagnosed as O. viverrini, was 1.9%. No metacercariae were found in cultured snakehead fish, although wild-caught snakehead fish had a FZT prevalence of 10.3%: 5.1% were O. viverrini; 2.6% H. pumilio; and 2.6% were Procerovum sp. These are the first reports of H. pumilio, Procerovum sp., and O. viverrini metacercariae in Vietnamese fish. These results indicate that consumption of improperly prepared fish represents a significant risk of acquiring FZTs in this south Vietnam region.

Survey for zoonotic liver and intestinal trematode metacercariae in cultured and wild fish in An Giang Province, Vietnam

Although Vietnam has a high risk of fishborne zoonotic trematode (FZT) infections for humans, little information exists on the epidemiology of these infections in the country's fish. Because of the importance of cultured catfish and snakehead production in An Giang province, a major production area in the Mekong Delta of Vietnam, a survey for FZTs was carried out in randomly selected fish farms between June 2005 and March 2006. For comparison, wild fish from the same area were also surveyed. A total of 852 cultured fish from 4 districts were collected and examined by pepsin digestion to determine their FZT infection status. In Tra catfish, the prevalence of all types of metacercariae was 2.6%, of which the prevalence of Haplorchis pumilio was 0.7%. The overall prevalence of metacercariae in wild fish was 30.6%, of which 10.3% harbored zoonotic species: H. pumilio (2.8%) and Procerovum sp. (5.6%). The prevalence of Opisthorchis metacercariae, which were diagnosed as O. viverrini, was 1.9%. No metacercariae were found in cultured snakehead fish, although wild-caught snakehead fish had a FZT prevalence of 10.3%: 5.1% were O. viverrini; 2.6% H. pumilio; and 2.6% were Procerovum sp. These are the first reports of H. pumilio, Procerovum sp., and O. viverrini metacercariae in Vietnamese fish. These results indicate that consumption of improperly prepared fish represents a significant risk of acquiring FZTs in this south Vietnam region.

Variation in worm assemblages associated with Pomacea canaliculata (Caenogastropoda, Ampullariidae) in sites near the Río de la Plata estuary, Argentina

Pomacea canaliculata is a common gastropod in freshwater habitats from Central and Northern Argentina, extending northwards into the Amazon basin. Several Platyhelminthes have been reported associated to P. canaliculata, sharing an intimate relationship with this gastropod host. The objectives of this study were to describe the symbiotic species assemblages associated to P. canaliculata in the study area, and to disclose differences among them. Samples were taken in three typical small streams and one artificial lentic lagoon, all connected with the Rio de la Plata estuary. The 81.53% were infested with different symbiotic (sensulato) species. Among the Platyhelminthes, the commensal Temnocephala iheringi Haswell, 1893 was highly prevalent in all samples, always in the mantle cavity. Four trematode taxa were recognized: (a) metacercariae of Echinostoma parcespinosum Lutz, 1924 in the mantle cavity and sporocysts in the digestive gland; (b) metacercariae of Dietziella egregia (Dietz, 1909) in the pericardial cavity; (c) unidentified xiphidiocercariae and (d) unidentified sporocysts and furcocercariae in the digestive gland. Nematode larvae and oligochaetes were found in two localities in the mantle cavity. Among the Annelida, Helobdella ampullariae Ringuelet, 1945 was found in the mantle cavity and lung of snails only from one locality. Our results show that although some of the symbionts are present in all localities, others are restricted to some particular ones, whether in their absolute numbers or in their relative abundance. Thus, eachhosting population at the studied localities may be defined by the particularcombination of symbionts that bears.

Seasonal maturation of Glypthelmins vitellinophilum (Trematoda: Digenea) in Lysapsus limellus (Anura: Pseudidae) from an Argentinian subtropical permanent pond

De dezembro de 1995 a novembro de 2000, a maturação sazonal de Glypthelmins vitellinophilum Dobbin, 1958, em seu hospedeiro definitivo, a rã Lysapsus limellus Cope, 1862, foi estudada em uma lagoa permanente subtropical no nordeste da Argentina. Os objetivos deste estudo foram: 1) determinar a dinâmica de infrapopulação do parasita, analisando o ciclo de maturação sazonal ao longo dos anos; e 2) examinar a relação entre intensidade de infecção do trematódeo em diferentes estádios do desenvolvimento (recrutamento, crescimento e maturação) e o comprimento de corpo da rã. De 1.400 espécimens de rãs em 60 meses (5 anos), foram achados 38% infetados com G. vitellinophilum, e a intensidade de infecção era 1-15 trematódeos por rã. Espécimes de G. vitellinophilum estavam presentes em L. limellus ao longo dos anos, mas não mostraram um ciclo sazonal pronunciado de maturação. São discutidas possíveis razões para estes resultados com referência a flutuações climáticas e fatores bióticos. O período infectante do parasita (estádio I) aconteceu no verão, outono e primavera, coincidentemente com o tempo de aparecimento de cada corte das rãs. Estas infecções eram principalmente registradas em tamanhos de corpo pequenos (classes 1 e 2) de L. limellus. Espécimes de parasitas juvenis e não grávidas (estádios II e III) eram encontradas em diferentes tamanhos de rãs ao longo do período de investigação. Espécimes de parasitas grávidas (estádio IV) eram geralmente registradas no outono, inverno e primavera, principalmente nos tamanhos de corpo maiores de rãs. O comprimento de corpo do trematódeo dos estádios I e IV eram significativa e positivamente correlatos com o comprimento de corpo da rã.

Effects of anti-allergic drugs on intestinal mastocytosis and worm expulsion of rats infected with Neodiplostomum seoulense

The effects of anti-allergic drugs on intestinal mastocytosis and the expulsion of Neodiplostomum seoulense were observed in Sprague-Dawley rats, after oral infection with 500 metacercariae. The drugs used were hydroxyzine (a histamine receptor H1 blocker), cimetidine (a H2 blocker), cyclosporin-A (a helper T-cell suppressant), and prednisolone (a T- and B-cell suppressant). Infected, but untreated controls, and uninfected controls, were prepared. Worm recovery rate and intestinal mastocytosis were measured on weeks 1, 2, 3, 5, and 7 post-infection. Compared with the infected controls, worm expulsion was significantly (P < 0.05) delayed in hydroxyzine- and cimetidine-treated rats, despite mastocytosis being equally marked in the duodenum of all three groups. In the cyclosporin-A- and prednisolone-treated groups, mastocytosis was suppressed, but worm expulsion was only slightly delayed, without statistical significance. Our results suggest that binding of histamine to its receptors on intestinal smooth muscles is more important in terms of the expulsion of N. seoulense from rats than the levels of histamine alone, or mastocytosis.

Surface ultrastructure of the adult stage of Acanthotrema felis (Trematoda: Heterophyidae

The surface ultrastructure of Acanthotrema felis (Trematoda: Heterophyidae) adults, recovered from a kitten experimentally infected with the metacercariae, was observed using a scanning electron microscope. The worm was leaf-like, ventrally concave and covered with scale-like multi-pointed tegumental spines. The spines on the anterior surface were short but broad, and had 10-12 pointed tips. The cytoplasmic processes protruded around the spines, like pockets for the spines. The ventrogenital opening was crescent, or kidney-shaped, and had protuberances with minute spines on its surrounding tegument. The spines on the posterior surface were long, but narrow, with 6-8 pointed tips. The cytoplasmic processes on this tegument were ridge-like, and elevated along the row of the spines. The surface ultrastructure of A. felis is generally similar to that of other heterophyid flukes, but some features are characteristic, and may be of taxonomic and bio-ecological significance.

Experimental life cycle of Philophthalmus gralli (Trematoda: Philophthalmidae) in Venezuela

Descriptions of the miracidium, mother redia, daughter redia, grandaughter redia, cercaria, metacercaria and adult stages of Philophthalmus gralli Mathis and Leger, 1910 recovered from experimental infections are presented. The intermediate host, Melanoides tuberculata, was collected from freshwater rivulets in Aguasanta and Yaguracual, Sucre State, Venezuela. Chicken were orally infected with cercariae and metacercariae, and metacercariae were introduced directly into the eyes by pipette. Both processes of infection produced adult worms. This is a new geographical record for P. gralli.

A sieving method for collecting the metacercariae of trematode parasites from freshwater fish.

This study describes a sieving method for the collection of metacercariae from frozen (-20 degrees C) freshwater fish. Digested fish tissue is filtered through a series of sieves; the crude filtrate is then centrifuged. Centrifugation produces a sediment from which metacercariae can be removed. Half of the metracercariae that were obtained from the fish meat that had been frozen for 10 days (-20 degrees C) were dead; the other half were alive and some larvae were moving slowly.

Intensity of trematode metacercariae in cyprinoid fish in Chiang Mal Province, northern Thailand.

The intensity of infection of trematode metacercariae was determined in five species of cyprinoid fish collected from Mae Ngud reservoir, Chiang Mai Province. These species were Thynnichthys thynnoides, Puntioplites proctozysron, Hampala macrolepidota, Puntius leiacanthus and Puntius gonionotus. T. thynnoides contained the highest number (83.0%) of metacercariae, whereas P. gonionotus had the fewest (0.19%). The caudal fin was the area of highest infection of metacercariae (49.39%), with the anal fin having the fewest (5.93%). Most metacercariae was isolated from Haplorchis taichui (63.27%), with an intensity variation of 0.3-165.2 metacercariae/fish.

Surface ultrastructure of excysted metacercariae of Haplorchis taichui (Trematoda: Heterophyidae).

The morphology of newly excysted juvenile Haplorchis taichui was studied using a light and a scanning electron microscope (SEM). The reproductive organs were well developed. The whole body surface was covered with numerous transverse rows of scale-like spines, which had 3-11 points at the tip. The spines on the dorsal were similar with those on the ventral surfaces in shape, size and number of points. The spines in anterior were digitated into 10-11 points, then 8-9 points and 7 points. The presence of 3 points in each spine was observed in the area adjacent to the excretory pore. Two types of sensory papillae existed throughout the body: type I, ciliated knob-like swellings and type II, round swellings of the tegument. The rapid maturation of H. taichui results from the development of both internal and external organs during the newly excysted stage.

Planorbid snails as potential molluscan intermediate host of a human intestinal fluke, Neodiplostomum seoulensis (Trematoda : Diplostomatidae) in Korea.

Three species of the pulmonate snails of the family Planorbidae have been reported from Korea; Gyraulus convexiusculus, Hippeutis (Helicorbis) cantori and Segmentina (Polypylis) hemisphaerula. Of these 3 species, only H. cantori is reported as the molluscan intermediate host of Neodiplostomum seoulensis, one of the important snail-borne human intestinal trematodes in Korea. However, S. hemisphaerula was also found to be an intermediate host for N. seoulensis. In field-collected snails, H. cantori and S. hemisphaerula were found shedding bifurcated cercariae of N. seoulensis, whereas no G. convexiusculus was found shedding cercariae. In experiments with laboratory-bred snails, only S. hemisphaerula was susceptible to miracidia of N. seoulensis. Tadpoles of Rana nigromaculata and R. rugosa were exposed to cercariae shed from field-collected and laboratory-bred S. hemisphaerula. All tadpoles of R. nigromaculata were found to be massively infected, but none of the tadpoles of R. rugosa were infected with larvae of N. seoulensis. Metacercariae from tadpoles of R. nigromaculata and the snake Rhabdophis tigrinus tigrinus were fed to rats, and eggs of N. seoulensis were detected in the rat feces one-week later. These rats were killed and adult N. seoulensis recovered from the small intestines. This is the first report of S. hemisphaerula as a molluscan intermediate host for N. seoulensis in Korea.

Eurytrema coelomaticum: influence of the infection on the reproduction and nucleic acids contents in the albumen gland and ovotestis of Bradybaena similaris

The number of eggs laid per snail in Bradybaena similaris and the nucleic acids (DNA and RNA) in the albumen gland and ovotestis were quantified in snails infected with sporocysts of the digenetic trematode Eurytrema coelomaticum. The total number of eggs laid per mollusc was reduced by 96.32 por cento at the end of the larval development. The DNA concentration increased by 700 por cento and the RNA concentration was reduced by 8,38 por cento by the time when the daughter sporocysts of E. coelomaticum were released from B. similaris. The relation between these values and the inhibition of the reproduction observed in infected molluscs is discussed.

Trematodes larvales de las familias diplostomidae, strigeidae y echinostomatidae en la Región Patagónica Argentina / Larval trematodes of diplostomidae, strigeidae and echinostomatidae in the Patagonian Region Argentina

Se describen tres cercarias pertenecientes a las familias diplostomidae, strigeidae y echinostomatidae (trematoda, digenea), emergidas de chilina sp (mollusca, gasteropoda) coleccionadas en el lago Escondido, Provincia de Río Negro, Argentina, entre enero 1987 y mayo de 1994

Comparative allometry growth of some marine fish digenetic trematodes

Allometric growth variation was compared for Plagioporus idoneus, Lepocreadium pegorchis, Opecoeloides furcatus, Bacciger israelensis, Aphanurus stossichi and Parahurleytrema trachinoti collected from East Mediterranean fishes ,. The pharynx, the oral and the ventral sucker diameters always showed a negative allometry. The other parameters tested were variable with the species. We study the effects of some environmental factors: the influence of the host species is analysed in Plagioporus idoneous, wich parasitizes Oblada melanura, Diplodus sargus and D. vulgaris and in Lepocreadium pegorchis, wich parasitizes Pagellus erythrinus, Lithognathus mormyrus and Spicara smaris; the influence of the microhabitat and the intensity of infection is analysed in Bacciger israelensis and Aphanurus stossichi, both parasites of Boops boops. We report significant differences with the host species, for the allometric growth of the testes; the effect of the microhabitat was revealed by the hindbody allometric value; no significant difference was detected in relation with the intensity of infection

Rudolphitrema chilensis sp. nov. un nuevo tremátodo digénico parásito del anuro chileno Eusophus roseus (Leptodactylidae) / Rudolphitrema chilensis sp. nov. a new digenic parasite of the Chilean anura Eusophus roseus (Leptodactylidae)

Se describe un nuevo tremátodo digenético perteneciente al género Rudolphitrema. La nueva especie es llamada Rudolphitrema chilensis sp. nov. y se ha encontrado en el intestino delgado del batracio chileno Eusophus roseus. Este nuevo tremátodo es comparado con las otras especies del género