The catholic taste of broad tapeworms - multiple routes to human infection.

Broad tapeworms (Cestoda: Diphyllobothriidea) are the principal agents of widespread food-borne cestodosis. Diphyllobothriosis and diplogonoporosis, caused by members of the genera Diphyllobothrium, Diplogonoporus and Adenocephalus, are the most common fish cestodoses with an estimated 20million people infected worldwide, and has seen recent (re)emergences in Europe due to the increasing popularity of eating raw or undercooked fish. Sparganosis is a debilitating and potentially lethal disease caused by the larvae of the genus Spirometra, which occurs throughout much of the (sub)tropics and is caused by the consumption of raw snakes and frogs, and drinking water contaminated by infected copepods. Both diseases are caused by several species, but the frequency by which the transition to humans has occurred has never been studied. Using a phylogenetic framework of 30 species based on large and small nuclear ribosomal RNA subunits (ssrDNA, lsrDNA), large subunit mitochondrial ribosomal RNA (rrnL) and cytochrome c oxidase subunit I (cox1), we hypothesize that humans have been acquired asaccidental hosts four times across the tree of life of diphyllobothriideans. However, polytomies prevent an unambiguous reconstruction of the evolution of intermediate and definitive host use. The broad host spectrum and the frequency with which switching between major host groups appears to have occurred, may hold the answer as to why accidental human infection occurred multiple times across the phylogeny of diphyllobothriideans. In this study Diplogonoporus is determined to be the junior synonym of Diphyllobothrium. Furthermore, we divide the latter polyphyletic genus into (i) the resurrected genus Dibothriocephalus to include freshwater and terrestrial species including Dibothriocephalus dendriticus, Dibothriocephalus latus and Dibothriocephalus nihonkaiensis as the most common parasites of humans, and (ii) the genus Diphyllobothrium to accommodate parasites from cetaceans including the type species Diphyllobothrium stemmacephalum and Diphyllobothrium balaenopterae n. comb. known also from humans. The non-monophyletic aggregate of marine species from seals is provisionally considered as incertae sedis.

Tumour-like anomaly of copepods-an evaluation of the possible causes in Indian marine waters.

Globally, tumour-like anomalies (TLA) in copepods and the critical assessment of their possible causes are rare. The exact causative factor and ecological consequences of TLA in copepods are still unclear and there is no quantitative data available so far to prove conclusively the mechanism involved in developing TLA in copepods. TLA in copepods are considered as a potential threat to the well-being of the aquatic food web, which prompted us to assess these abnormalities in Indian marine waters and assess the possible etiological agents. We carried out a focused study on copepods collected from 10 estuarine inlets and five coastal waters of India using a FlowCAM, advanced microscopes and laboratory-incubated observations. The analysis confirmed the presence of TLA in copepods with varying percentage of incidence in different environments. TLA was recorded in 24 species of copepods, which constituted ~1-15 % of the community in different environments. TLA was encountered more frequently in dominant copepods and exhibited diverse morphology; ~60 % was round, dark and granular, whereas ~20 % was round/oval, transparent and non-granular. TLA was mostly found in the dorsal and lateral regions of the prosome of copepods. The three suggested reasons/assumptions about the causes of TLA such as ecto-parasitism (Ellobiopsis infection), endo-parasitism (Blastodinium infection) and epibiont infections (Zoothamnium and Acineta) were assessed in the present study. We did find infections of endo-parasite Blastodinium, ecto-parasite Ellobiopsis and epibiont Zoothamnium and Acineta in copepods, but these infectious percentages were found <1.5 % to the total density and most of them are species specific. Detailed microscopical observations of the samples collected and the results of the incubation experiments of infected copepods revealed that ecto-parasitism, endo-parasitism and epibiont infections have less relevance to the formation of TLA in copepods. On the other hand, these studies corroborated the view that wounds on the exoskeleton caused by partial predation as the potential reason for the TLA of copepods in Indian waters.

Paranucleospora theridion n. gen., n. sp. (Microsporidia, Enterocytozoonidae) with a Life Cycle in the Salmon Louse (Lepeophtheirus salmonis, Copepoda) and Atlantic Salmon (Salmo salar).

Paranucleospora theridion n. gen, n. sp., infecting both Atlantic salmon (Salmo salar) and its copepod parasite Lepeophtheirus salmonis is described. The microsporidian exhibits nuclei in diplokaryotic arrangement during all known life-cycle stages in salmon, but only in the merogonal stages and early sporogonal stage in salmon lice. All developmental stages of P. theridion are in direct contact with the host cell cytoplasm or nucleoplasm. In salmon, two developmental cycles were observed, producing spores in the cytoplasm of phagocytes or epidermal cells (Cycle-I) and in the nuclei of epidermal cells (Cycle-II), respectively. Cycle-I spores are small and thin walled with a short polar tube, and are believed to be autoinfective. The larger oval intranuclear Cycle-II spores have a thick endospore and a longer polar tube, and are probably responsible for transmission from salmon to L. salmonis. Parasite development in the salmon louse occurs in several different cell types that may be extremely hypertrophied due to P. theridion proliferation. Diplokaryotic merogony precedes monokaryotic sporogony. The rounded spores produced are comparable to the intranuclear spores in the salmon in most aspects, and likely transmit the infection to salmon. Phylogenetic analysis of P. theridion partial rDNA sequences place the parasite in a position between Nucleospora salmonis and Enterocytozoon bieneusi. Based on characteristics of the morphology, unique development involving a vertebrate fish as well as a crustacean ectoparasite host, and the results of the phylogenetic analyses it is suggested that P. theridion should be given status as a new species in a new genus.

Life cycle and molecular phylogeny of the dinoflagellates Chytriodinium and Dissodinium, ectoparasites of copepod eggs.

The dinoflagellates Chytriodinium affine, C. roseum and Dissodinium pseudolunula are ectoparasites of crustacean eggs. Here, we present new observations regarding their life cycle based on coastal plankton samples and incubations and analyze their molecular phylogeny using the small subunit ribosomal RNA gene (SSU rDNA) as a marker. In contrast to the typical stages already documented for its life cycle, we observed that D. pseudolunula dinospores may exceptionally differentiate inside a globular cyst. Despite its parasitic life style, the cysts and dinospores of D. pseudolunula contain chlorophyll a. We obtained the first SSU rDNA sequences for the genera Chytriodinium (the type C. roseum and C. affine) and Dissodinium (D. pseudolunula). Classical taxonomical schemes have ascribed these genera to the order Blastodiniales. However, our SSU rDNA-based phylogenetic analysis shows that these ectoparasites form a clade in the Gymnodinium sensu stricto group, unarmored dinokaryotic dinoflagellates of the order Gymnodiniales. They branch in a subgroup composed of warnowiids, polykrikoids, the type of Gymnodinium, G. fuscum and G. aureolum. Although Chytriodinium and Dissodinium appear to be relatives based on SSU rDNA phylogeny, feeding and host specificity, their life cycles are substantially different. Based on these data we consider that the type of life cycle is a poor criterion for classification at the family level. We suggest that the morphology of the infective cell is probably the most reliable phenotypic characteristic to determine the systematic position of parasitic dinoflagellates.

Attachment of the peritrich epibiont Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) to artificial substrates in a natural environment / Colonização de substratos artificiais pelo peritríquio epibionte Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia), em um ambiente natural

Peritrich ciliates are commonly found as epibionts, colonizing living organisms, or attached to non-living substrates in freshwater, estuarine and marine environments. Several species of peritrich epibionts are obligate, which means that they are able to only colonize other organisms, while others are facultative attaching to living or non-living substrates. The peritrich Zoothamnium intermedium is commonly found as epibiont on the copepod species Acartia tonsa and Eurytemora affinis in Chesapeake Bay, USA. Previous studies demonstrated that Z. intermedium is not able to attach to non-living substrates in the laboratory; with free-swimming stages (telotrochs) dying when living substrates are not available for colonization. The present study investigated the ability of Z. intermdium to colonize artificial substrates in the field. Observations were carried out while the peritrich ciliate was colonizing copepods in Rhode River, a tributary of Chesapeake Bay. Results demonstrated that four species of Zoothamnium were recovered from artificial substrates, but none of them was Z. intermedium. At the same time, Z. intermedium was colonizing adults and copepodites of E. affinis and A. tonsa during the whole study period. These results, in addition to laboratory observations, suggest that Z. intermedium is an obligate epibiont.

Ciliados peritríquios são normalmente encontrados como epibiontes, colonizando substratos vivos, ou em substratos inanimados em ambientes de água doce, estuarinos e marinhos. Muitas espécies de peritríquios epibiontes podem ser consideradas obrigatórias quando estão aptas a colonizar apenas substratos vivos, ou facultativos quando conseguem colonizar substratos vivos ou inanimados. A espécie de ciliado peritríquio Zoothamnium intermedium é encontrada colonizando os copépodos Acartia tonsa e Eurytemora affinis na Chesapeake Bay, EUA. Estudos preliminares demonstraram que Z. intermedium não consegue colonizar substratos inanimados em laboratório e que os estágios livre-natantes (telotróquios) morrem quando não estão expostos a algum substrato vivo. No presente estudo, foi investigada a habilidade de Z. intermedium colonizar substratos artificiais no campo. As observações foram realizadas no Rhode River, um afluente da Chesapeake Bay, enquanto Z. intermedium era encontrado colonizando copépodos. Os resultados demonstraram que quatro espécies de Zoothamnium colonizaram os substratos artificiais, mas nenhuma delas era Z. intermedium. No mesmo período, Z. intermedium foi encontrado colonizando copepoditos e adultos de A. tonsa e E. affinis. Estes resultados, juntamente com as observações de laboratório, sugerem que Z. intermedium é um epibionte obrigatório.

Growth of the peritrich epibiont Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) estimated from laboratory experiments / Crescimento do peritríquio epibionte Zoothamnium intermedium Precht, 1935 (Ciliophora, Peritrichia) obtido através de experimentos em laboratório

Peritrich ciliates are commonly found colonizing living substrates. Although this a well known phenomenon, biological aspects of this relationship need to be studied in more detail. Assessment of growth rates in peritrichs has been the subject of very few studies. Only species in the genera Carchesium Ehrenberg, 1830 and Vorticella Linnaeus, 1767 had their growth rates evaluated in the field and in the laboratory. In the present study, growth, colonization (colonies/host), and proliferation (zooids/colony) rates of the peritrich epibiont Zoothamnium intermedium Precht, 1935 attached to the calanoid copepod Acartia tonsa Dana 1848 were evaluated in the laboratory in two food regimes: bacteria only, and algal based diet. Results showed that growth, colonization, and proliferation rates were similar for both diets. Maximum growth rates obtained for Z. intermedium was 0.85 and 0.83 per day, for bacteria and algae respectively. Maximum colonization rates were 0.5 per day for both diets, and the maximum proliferation rates were 0.44 and 0.42 per day for bacteria and algae respectively. These results demonstrate that Z. intermedium is able to grow at the same rate of other peritrichs on bacterial and algal based diets.

Ciliados peritríquios são geralmente encontrados colonizando a superfície de outros organismos. Embora este fenômeno seja bem documentado, certos aspectos biológicos desta associação ainda precisam ser estudados. Taxas de crescimento em peritríquios foram objeto de pouquíssimos estudos, visto que apenas espécies nos gêneros Carchesium e Vorticella tiveram suas taxas de crescimento calculadas em experimentos de campo e de laboratório. No presente trabalho, taxas de crescimento, colonização (colônias/hospedeiro) e proliferação (zooides/colônia) do peritríquio epibionte Zoothamnium intermedium colonizando o copépodo calanoide Acartia tonsa foram avaliadas em laboratório com duas dietas: bactéria somente e alga. Resultados demonstraram que taxas de crescimento, colonização e proliferação foram semelhantes para as duas dietas. A taxa de crescimento máxima observada para Z. intermedium foi de 0.85 e 0.83 por dia para bactéria e alga, respectivamente. A taxa máxima de colonização foi 0.5 por dia para as duas dietas e a taxa máxima de proliferação foi de 0.44 e 0.42 por dia para bactéria e alga, respectivamente. Estes resultados demonstram que Z. intermedium cresce em taxas semelhantes a outras espécies de peritríquios em dietas de bactérias ou de algas.

Experimental infection in Notodiaptomus sp. (Crustacea: Calanoida) with larvae of Camallanus sp. (Nematoda: Camallanidae)

This trial registered the experimental infection viability with nematode larvae Camallanus sp. in Notodiaptomus sp., a crustacean, which can be an intermediate host. Adult females of nematode were dissected from the intestines of Xiphophorus maculatus (Osteichthyes: Poeciliidae), at a fish farm in the State of São Paulo. Females were slightly compressed for larvae release, collected with Pasteur pipette and separated on Petri dishes with 9ml filtered water at 28.1°C, from zooplankton culture. Treatments consisted of Petri dishes with 60 and 105 copepods, in which 120, 150 and 210 larvae of nematode were added in four replications. Twenty-four and 36h after exposition to the larvae, the copepods were fixed in 70 percent alcohol to record the amount of fixed larvae. Twenty four hours after exposition, 60 copepods group with 120 larvae showed significantly higher prevalence (46.5 percent) when compared to 105 copepods and 120 larvae (33.2 percent). Thus, these answers suggested that 120 larvae were enough for a successful infectivity. Experimental infection was available and so, it was used as a pattern to life cycle studies of camallanid nematodes and hosts susceptibility tests.

A viabilidade da infecção experimental com larvas do nematóide Camallanus sp. em Notodiaptomus sp., crustáceo com potencial para hospedeiro intermediário foi avaliada. Fêmeas adultas do nematóide foram extraídas de Xiphophorus maculatus (Osteichthyes: Poeciliidae), provenientes de piscicultura de peixes ornamentais no estado de São Paulo. As fêmeas foram ligeiramente pressionadas para liberar as larvas, coletadas com pipeta Pasteur e separadas em placas de Petri contendo 9ml de água filtrada a 28,1°C do próprio cultivo de zooplâncton. Os tratamentos consistiram de placas contendo 60 e 105 copépodes onde se adicionou 120, 150 e 210 larvas de nematóides em quatro repetições. Nos tempos de 24 e 36h após a exposição às larvas, os copépodes foram fixados em álcool 70 por cento para quantificação de larvas. Após 24h de exposição, o grupo com 60 copépodes na presença de 120 larvas apresentou maior prevalência (46,5 por cento) do que 105 copépodes com 120 larvas (33,2 por cento). Sugere-se que 120 larvas foram suficientes para o sucesso da infecção. A infecção experimental mostrou-se viável, servindo de modelo para o estudo do ciclo de vida de camalanídeos e testes de susceptibilidade de hospedeiros.

Sticholonche zanclea (Protozoa, Actinopoda) in fecal pellets of copepods and Euphausia sp. in Brazilian coastal waters / Sticholonche zanclea (Protozoa, Actinopoda) em pelotas fecais de copépodos e Euphasia sp. em águas costeiras brasileiras

Fecal pellets produced by mesozooplanktonic copepods (Centropages velificatus and Paracalanus parvus) and macrozooplanktonic Euphausiacea (Euphausia sp.) were examined using scanning electron microscopy. Fragments of the protozoan Sticholonche zanclea were found in both copepod and in Euphausia sp. fecal pellets, even when the abundance of the protozoan in the water was low. The results suggest that S. zanclea is an important food resource for different trophic levels, including meso- and macrozooplankton, in Brazilian coastal waters.

Pelotas fecais produzidas por copépodos mesozooplanctônicos (Centropages velificatus e Paracalanus parvus) e por Euphasiacea macrozooplanctônico (Euphasia sp) foram examinadas em microscópio eletrônico de varredura. Fragmentos do protozoário Sticholonche zanclea foram encontrados nas pelotas fecais dos copépodos e de Euphasia sp, mesmo quando a abundância do protozoário no ambiente foi bastante reduzida. Os resultados sugerem que S. zanclea pode representar um importante recurso alimentar para diferentes níveis tróficos, incluindo meso e macrozooplâncton, em águas costeiras brasileiras.

Waterborne zoonotic helminthiases.

This review deals with waterborne zoonotic helminths, many of which are opportunistic parasites spreading directly from animals to man or man to animals through water that is either ingested or that contains forms capable of skin penetration. Disease severity ranges from being rapidly fatal to low-grade chronic infections that may be asymptomatic for many years. The most significant zoonotic waterborne helminthic diseases are either snail-mediated, copepod-mediated or transmitted by faecal-contaminated water. Snail-mediated helminthiases described here are caused by digenetic trematodes that undergo complex life cycles involving various species of aquatic snails. These diseases include schistosomiasis, cercarial dermatitis, fascioliasis and fasciolopsiasis. The primary copepod-mediated helminthiases are sparganosis, gnathostomiasis and dracunculiasis, and the major faecal-contaminated water helminthiases are cysticercosis, hydatid disease and larva migrans. Generally, only parasites whose infective stages can be transmitted directly by water are discussed in this article. Although many do not require a water environment in which to complete their life cycle, their infective stages can certainly be distributed and acquired directly through water. Transmission via the external environment is necessary for many helminth parasites, with water and faecal contamination being important considerations. Human behaviour, particularly poor hygiene, is a major factor in the re-emergence, and spread of parasitic infections. Also important in assessing the risk of infection by water transmission are human habits and population density, the prevalence of infection in them and in alternate animal hosts, methods of treating sewage and drinking water, and climate. Disease prevention methods, including disease surveillance, education and improved drinking water treatment are described.

Aggregation of helminths: the role of feeding behavior of fish hosts.

Individual Arctic charr (Salvelinus alpinus) from Fjellfrøsvatn, northern Norway, could be categorized by their stomach contents as zooplanktivores or benthivores. Feeding specialization among these fish was evident from negative correlations between helminths transmitted by pelagic copepods (Diphyllobothrium dendriticum and D. ditremum) and those transmitted by the benthic amphipod Gammarus lacustris (Cystidicola farionis and Cyathocephalus truncatus). Occurrences of parasite species acquired from the same types of invertebrate were positively correlated in the fish. Strong relationships among habitat use, diet, and helminth infections among the Arctic charr indicated persistent foraging patterns involving long-term habitat use and feeding specialization. The distribution of all parasite species was highly aggregated in the fish samples, measured by the exponent k of the fitted negative binomial distributions (range: 0.5-7.5) and the variance-to-mean ratios (s2/mean, range: 5-85). Charr specializing on either copepods or Gammarus predominantly contributed to high-intensity class intervals within the overall frequency distributions of the corresponding parasite species. Such fish had low infection intensities of helminths transmitted by other prey organisms. The detailed analyses of the parasite frequency distributions for fish with different habitat or feeding preferences evidently show how heterogeneity in trophic behavior contributes strongly to the commonly observed aggregation of helminths among hosts under natural conditions.

A hyperparasitic microsporidian infecting the salmon louse, Lepeophtheirus salmonis: an rDNA-based molecular phylogenetic study.

The sea louse, Lepeophtheirus salmonis, is an obligate ectoparasitic copepod that lives on the external surface of salmonid fish. It is the most common ectoparasite of marine cage-reared salmonids, causing major economic loss to the aquaculture industry. During a sea louse monitoring programme, samples of L. salmonis were found to harbour an unreported microsporidian parasite. The microsporidian was observed in pre-adult and adult stages of both male and female copepods, with a prevalence of up to 5%. Unfixed spores were slightly pyriform in shape measuring 2.34 microm by 1.83 microm (+/- 0.01 microm) and were not observed to be enclosed by a sporophorous vesicle. The microsporidian infection was observed in all areas of the copepods' body, xenoma-like cysts forming directly under the cuticle in the epidermal tissue layer. In the present study, rDNA (530f-580r) sequence data gathered from the unidentified microsporidian parasite isolated from infected sea lice were compared with equivalents available in the databases in an attempt to identify its systematic position. The microsporidian was found to group within the phylogenetic clade containing the family Enterocytozoonidae, being most similar to members of the intranuclear genus Nucleospora. This is the first report of a hyperparasitic microsporidian infecting a caligid copepod.

Aspectos anátomo-patológicos da parasitose por Lernaea cyprinacea (L) (Crustacea: Copepoda) em tambaqui (Colossoma macropomum Cuvier, 1818) / Anatomo-pathological aspects of the parasitism caused by Lernaea cyprinacea (L) (Crustacea: Copepoda) in the "tambaqui" (Colossoma macropomum Cuvier, 1818)

Uma amostragem de trinta tambaquis (Colossoma macropomum Cuvier, 1818), com idade e peso variados, foi examinada para a detecção de parasitismo por Lernaea cyprínacea; sete deles apresentam o ectoparasita. Os peixes com lerneose possuíam idade entre quatro meses e um ano, com peso máximo de 1 kg. Vinte peixes adultos com idade acima de quatro anos, não mostraram a presença de L. cyprínacea. O número máximo de copépodes encontrados por hospedeiro foi três. As nadadeiras e suas bases de inserção no corpo foram o local mais comum de fixação nos peixes pesquisados. A lesão provocada por L. cyprínacea se apresentou, macroscopicamente, como uma hemorragia discreta e limitada ao ponto de inserção do copépode. A análise histopatológica demonstrou infiltração leococitária mononuclear e neovascularização com intensa hemorragia nos tecidos ao redor da estrutura de fixação do parasita. Em um exemplar, a reação inflamatória foi seguida de ulceração e pelo início de um processo de fibrose no local de penetração do parasita.

A sample of thirty specimens of the "tambaqui" (Colossoma macropomum Cuvier, 1818), was collected in the fish pond of the Agricultural College ldelfonso Bastos Borges at Bom Jesus de ltabapoana, State of Rio de Janeiro. They had varied ages and weights and were examined to detect the ectoparasite L. cyprinacea. Seven of them presented lerneosis and had from four months to one year with a maximum of 1 kg. Twenty adults specimens with more than four years did not present the parasitis. The maximum number of copepods per host was three and these parasites were usually fixed in the fins and in their attachment bases in the fish body. Macroscopically, the injury caused by L. cyprinacea showed a discrete and localized hermorrhage at the attachment area. The histopathological analysis exhibited a mononuclear leococitic infiltration and neovascularization with hemorrhage around the tissues of the appendages of the parasite. In some cases, the inflamatory reaction involved them, trying to isolate copepod from the tissue of the host. In one specimen, it was observed that the inflamatory reaction was followed by ulceration and by a fibrous process in the penetrating area of the parasite.