Cryptobia iubilans Infections in Discus Fish in Trinidad and Tobago.

Discus (Symphysodon spp.) are costly and prized specimens in the international ornamental fish trade. The majority of discus submitted to the Aquatic Animal Health Unit at the University of the West Indies School of Veterinary Medicine for necropsy between September 2010 and September 2015 had lesions consistent with Cryptobia iubilans infection, thus prompting this study. To determine the prevalence of the flagellated gastrointestinal protozoan C. iubilans in discus fish, 32 discus were sourced from 10 suppliers, including breeders, importers, and hobbyists across Trinidad. Fish were euthanized, and the internal organs, particularly the stomach and intestine, were observed under a light microscope for characteristic granulomatous lesions and/or live C. iubilans parasites. All wet-mount slides on which granulomas were observed were also Ziehl-Neelsen acid-fast stained to presumptively exclude the presence of Mycobacterium spp., the main differential when diagnosing C. iubilans-associated granulomatous gastritis or to determine the presence of dual infections. Further histological analyses were performed on stomach and intestinal sections, and transmission electron microscopy was used to confirm the parasite in stomach sections. The prevalence of C. iubilans infection was found to be 81.3%, and the prevalence of presumptive dual infections with Mycobacterium spp. was found to be 21.9%. To the best of our knowledge, this is the first documented study of C. iubilans infections in the wider Caribbean region.

Glucocorticoid receptors on and in a unicellular organism, Cryptobia salmositica.

This is the first report to our knowledge that demonstrates a functional steroid hormone receptor in a protozoon. The study used Cryptobia salmositica, a pathogenic haemoflagellate found in salmonid fishes. It has been previously shown that cortisol and dexamethasone (a synthetic glucocorticoid) enhanced the multiplication of C. salmositica under in vitro conditions indicating the presence of glucocorticoid receptors on/in the parasite. Also, the glucocorticoid receptor antagonist, mifepristone (RU486), inhibited the stimulatory effect of the two glucocorticoids on parasite multiplication. In the present study, we used an antibody (produced in a rabbit against glucocorticoid receptor protein) agglutination test and confocal microscopy with immunohistofluorescence staining to demonstrate cortisol-glucocorticoid receptor-like protein receptors on the plasma membrane and in the cytoplasm of the parasite. In two in vitro studies, the addition of 50ngml(-1) of RU486 was more effective in inhibiting parasite replication in cultures with 7,000parasitesml(-1) than in cultures with 14,000parasitesml(-1). Also, 100ngml(-1) of RU486/ml was more effective than 50ngml(-1) in inhibiting parasite multiplication in the 14,000 parasitesml(-1) cultures. These in vitro studies indicate that the number of binding sites on/in the parasite is finite. The findings may be important in future studies especially on steroid receptor signalling pathways and dissection of ligand-receptor interactions, and for evaluating the adaptations that develop in pathogens as part of the host-parasite interaction.

Immunity against selected piscine flagellates.

This discussion is on immune response to Amyloodinium ocellatum, Cryptobia salmositica, Trypanoplasma borreli and Trypanosoma carassii. Piscidin and histone-like proteins enhance innate resistance to Amyloodinium. Fish that are naturally resistant to Cryptobia and Trypanoplasma can be bred. Cryptobia resistance in charr is controlled by a dominant Mendelian locus and protection is via the Alternative Pathway of Complement Activation. Studies on Cryptobia-tolerant charr may lead to production of transgenic Cryptobia-tolerant salmon. Innate response to T. borreli is associated with NO in macrophages. Transferrin regulates resistance and carp have been bred for transferrin genotypes. Recovered fish are protected from homologous challenge, and complement fixing antibodies are crucial in protection. Studies on antigens in T. carassii may lead to a vaccine. There are two vaccines against cryptobiosis; a single dose of the attenuated vaccine protects salmonids. On challenge fish inoculated with the metalloprotease-DNA vaccine do not have the disease and they recover faster.

Prevalência, distribuição geográfica e sazonal de protozoários e mixozoários parasitos de jaú (Zungaro jahu) no Pantanal Matogrossense / Prevalence, geographic and seasonal distribution of protozoan and myxozoan parasites of jaú (Zungaro jahu) in the Pantanal of Mato Grosso, Brazil

Estudo realizado no Pantanal Matogrossense, avaliou a prevalência, a distribuição geográfica e sazonal de protozoários e mixozoários parasitos de jaú (Zungaro jahu). Os peixes foram capturados no Sul do Pantanal, na região dos rios Aquidauana, Miranda e Paraguai, em 2001, 2002 e 2003, na região Central (Parque Nacional do Pantanal - PARNA Pantanal) em 2003, 2004, 2005 e 2008, e na região Norte (rios Cuiabá e Manso, no município de Nobres) em 2003, 2004 e 2005. Foi identificado Trichodina sp. parasitando pele e brânquias de jaú nas três regiões estudadas. Ocorrência de Epistylis sp. na pele e Cryptobia sp. nas brânquias foram restritas às coletas da região Central, enquanto Ichthyophthirius multifiliis foi identificado parasitando a pele nas três regiões estudadas. Também foi observada a ocorrência de mixozoários, Myxobolus cordeiroi parasitando vários órgãos e Henneguya sp. parasitando brânquias de jaú das três regiões estudadas.

In a study carried out in the Pantanal of Mato Grosso, Brazil, the prevalence, geographic and seasonal distribution of protozoan and myxozoan parasites of Zungaro jahu was evaluated. The fish were captured in the southern region of Pantanal Mato-grossense (Aquidauana, Miranda and Paraguay rivers) in 2001, 2002 and 2003, in the central region (Pantanal National Park - PARNA Pantanal) in 2003, 2004, 2005 and 2008, and in the northern region (Cuiabá and Manso rivers, in the municipality of Nobres) in 2003, 2004 and 2005. Trichodina sp. was identified parasitized skin and gills of jaú in the three regions studied. Epistylis sp. parasitized skin and Cryptobia sp. the gills and were restricted to the Central region, whilst Ichthyophthirius multiiiliis parasitized skin in the three regions studied. The occurrence of myxozoans was also observed: Myxobolus cordeiroi parasitized several organs and Henneguya sp. parasitized the gills of jaú in the three regions studied.