BackgroundHelminth parasites represent a significant threat to the health of human and animal populations, and there is a growing need for tools to treat, diagnose, and prevent these infections. Recent work has turned to the gut microbiome as a utilitarian agent in this regard; components of the microbiome may interact with parasites to influence their success in the gut, meaning that the microbiome may encode new anthelmintic drugs. Moreover, parasite infections may restructure the microbiome’s composition in consistent ways, implying that the microbiome may be useful for diagnosing infection. The innovation of these utilities requires foundational knowledge about how parasitic infection, as well as its ultimate success in the gut and impact on the host, relates to the gut microbiome. In particular, we currently possess limited insight into how the microbiome, host pathology, and parasite burden covary during infection. Identifying interactions between these parameters may uncover novel putative methods of disrupting parasite success.ResultsTo identify interactions between parasite success and the microbiome, we quantified longitudinal associations between an intestinal helminth of zebrafish, Pseudocapillaria tomentosa, and the gut microbiome in 210 4-month-old 5D line zebrafish. Parasite burden and parasite-associated pathology varied in severity throughout the experiment in parasite-exposed fish, with intestinal pathologic changes becoming severe at late time points. Parasite exposure, burden, and intestinal lesions were correlated with gut microbial diversity. Robust generalized linear regression identified several individual taxa whose abundance predicted parasite burden, suggesting that gut microbiota may influence P. tomentosa success. Numerous associations between taxon abundance, burden, and gut pathologic changes were also observed, indicating that the magnitude of microbiome disruption during infection varies with infection severity. Finally, a random forest classifier accurately predicted a fish’s exposure to the parasite based on the abundance of gut phylotypes, which underscores the potential for using the gut microbiome to diagnose intestinal parasite infection.ConclusionsThese experiments demonstrate that P. tomentosa infection disrupts zebrafish gut microbiome composition and identifies potential interactions between the gut microbiota and parasite success. The microbiome may also provide a diagnostic that would enable non-destructive passive sampling for P. tomentosa and other intestinal pathogens in zebrafish facilities.Electronic supplementary materialThe online version of this article (10.1186/s40168-019-0622-9) contains supplementary material, which is available to authorized users.

No abstract

The dietary supplementation of prebiotics, probiotics and symbiotic in hybrid surubins (a Pseudoplatystoma corruscans and P. fasciatum cross) was evaluated for the effects on their autochthonous intestinal microbiota and on haematological and immunological parameters. A total of 160 fish were divided into four treatment groups with four replicates each. The treatment groups were fed with the following diets for 15 days: control diet without supplementation; 0.5% inulin (prebiotic) supplementation; Weissella cibaria (CPQBA 001-10 DRM 02) (7.87 ± 0.2 log CFU g )1 ) supplementation; or 0.5% inulin and W. cibaria supplementation (symbiotic group). The midgut intestines of the fish with the symbiotic diet supplementation had higher concentrations of lactic acid bacteria (7.07 ± 1.11 log CFU g )1 ) and low levels of Vibrio spp (1.90 ± 0.60 log CFU g )1 ) and Pseudomonas spp (2.23 ± 1.48 log CFU g )1 ). In addition, increased erythrocytes and reduced circulating neutrophils were observed in this group. No differences in blood glucose, serum protein or lysozyme levels were detected between treatment groups. However, a higher concentration of total immunoglobulin was observed in fish fed with the probiotic and symbiotic diets. The addition of 0.5% inulin (prebiotic) thus W. cibaria (probiotic) to the diet of Pseudoplatystoma hybrid surubins reduce the number of pathogenic bacteria and stimulate the beneficial intestinal microbiota and may possibly alter their immune defence system.

The effect of Goezia leporini Martins & Yoshitoshi, 2003 (Nematoda: Anisakidae) infection on the haematological characteristics of cultivated Leporinus macrocephalus (Osteichthyes:Anostomidae) was studied. Paleness of gills, kidneys, liver and heart, black spots on the kidney and accumulation of fluid in the visceral cavity, stomach and intestines were observed. Gall bladder content had pale and translucent aspect. Strong and slight positive correlations between number of nematodes and fish weight were estimated within the 0-100g and 100-200g fish weight group, respectively. Blood smears from infected fish showed variation in erythrocyte size (anisocytosis) and shape (poikilocytosis), and also dividing erythrocytes. No significant alteration (P>0.05) was shown as to erythrocyte, leukocyte count, haemoglobin concentration and thrombocyte and monocyte percentage. Parasite infection provoked significant reduction (P<0.05) in hematocrit, mean corpuscular volume, mean corpuscular haemoglobin concentration and lymphocyte percentage. On the other hand, significant increase (P<0.05) in neutrophil and eosinophil percentage in circulating blood of infected fish was observed. This is the first report regarding haematology of nematode infected freshwater cultivated fish in Brazil.Keywords: Brazilian fish, piauçu, Leporinus macrocephalus, Nematoda, Goezia leporini, haematology RESUMO Estudou-se efeito da infecção por Goezia leporini

No abstract

No abstract

The Phylum Protozoa brings together several organisms evolutionarily different that may act as ecto or endoparasites of fishes over the world being responsible for diseases, which, in turn, may lead to economical and social impacts in different countries. Apart from the recent advances for the diagnosis of fish diseases in Brazil, little is known on the protozoan parasites and their relationship with environment and host. This revision presents the most important protozoan parasites found in farmed fish from Brazil, not only with emphasis on its diagnosis, biology, transmission and host-parasite relationship, but also on some information that may be useful to researchers in determining the correct diagnosis in fish farms.Keywords: Fish parasites, disease, ciliate, dinoflagellate, pathogenicity. ResumoO filo Protozoa reúne diversos organismos evolutivamente distintos que podem atuar como ecto ou endoparasitos de peixes em todo o mundo, sendo responsáveis por doenças as quais, por sua vez, podem ocasionar impactos econômico e social nos diferentes países. Apesar dos recentes avanços no campo de diagnóstico de doenças em peixes no Brasil, ainda pouco se conhece sobre a fauna de protozoários parasitos de peixes e suas relações com o ambiente e hospedeiro. Esta revisão apresenta os mais importantes protozoários parasitos encontrados em peixes cultivados no Brasil, não apenas com ênfase no seu diagnóstico, biologia, transmissão e relação hospedeiro-parasito, mas também algumas informações que podem ser úteis para pesquisadores para o correto diagnóstico em pisciculturas.Palavras-chave: Parasitos de peixes, enfermidade, ciliado, dinoflagelado, patogenicidade.

Summary :The present work, studied the effect of 0, 1,000, 1,500 and 2,000 mg of garlic powder/kg dry ration for Piaractus mesopotamicus (Osteichthyes: Characidae), weighting 73.6 ± 39.4 g and measuring 15.0 ± 2.7 cm, fed for a period of 15, 30 and 45 days. Fifteen days after treatment with 1,000 and 2,000 mg of garlic/kg dry ration, significant reduction of Anacanthorus penilabiatus (Monogenea: Dactylogyridae) in the gills was related. Nevertheless, the addition of garlic to the ration caused significant increase in the erythrocyte number and in the thrombocyte percentage in the circulating blood. However, a decrease in the lymphocyte percentage was also observed. After 45 days, fish fed with garlic showed significant increase in the erythrocyte number, leucocyte, haemoglobin rate, hematocrit and thrombocyte.