D. Hoole

Diseases of carp and other cyprinid fishes

Acknowledgements. Preface. 1 Introduction. 1.1 Geographical distribution. 1.2 Economic importance of cyprinids. 2 Cyprinid Biology. 2.1 Water: the controlling factor. 2.2 Basic external anatomy. 2.3 Basic internal anatomy. 3 Disease Symptoms. 3.1 Behavioural symptoms of disease. 3.2 General external visual signs. 3.3 Internal signs of disease. 4 Infectious Diseases - Viruses, Bacteria and Fungi. 4.1 Viral pathogens and diseases. 4.2 Bacterial pathogens and diseases. 4.3 Fungal pathogens and diseases. 4.4 Zoonoses. 5 Infectious Diseases - Parasites. 5.1 Protozoan parasites and diseases. 5.2 Monogenean flukes. 5.3 Digenean flukes (trematodes). 5.4 Cestodes (the tapeworms). 5.5 Nematodes. 5.6 Acanthocephalans (spiny headed worms). 5.7 Mollusca (Glochidia). 5.8 Annelid worms (leeches). 5.9 Crustacea. 5.10 Zoonoses. 6 Noninfectious diseases. 6.1 Self-inflicted injuries. 6.2 Injuries caused by fish and other animals. 6.3 Injuries caused by human activities. 6.4 Developmental and physiological diseases. 6.5 Common disease problems. 6.6 Sterility. 6.7 Tumours. 6.8 Longevity and senile-related diseases. 7 Environmentally Induced Diseases. 7.1 Environmental diseases caused by natural events. 7.2 Environmental diseases caused by human activities. 7.3 Water temperature. 7.4 Dissolved gases. 7.5 pH. 7.6 Nitrogenous wastes. 7.7 Other pollutants. 7.8 Environmental stressors and diseases. 7.9 Measurement of some environmental water parameters. 8 Nutritionally Induced Diseases. 8.1 Natural foods. 8.2 Artificial foods. 8.3 Nutrition related diseases. 8.4 Starvation. 8.5 Nutritional toxicity disorders. 8.6 Overfeeding. 8.7 Diseases associated with live food organisms. 8.8 Diseases associated with feeding sick or dead fish. 9 Diseases of Eggs and Fry. 9.1 Eggs. 9.2 Fry. 9.3 Predation of eggs and fry. 10 Management of Fish Health. 10.1 Introduction to site management plans. 10.2 Trade organizations and other bodies. 11 Future Developments. 11.1 Rapid diagnostic methods. 11.2 Vaccine development. 11.3 Trends in chemotherapy. 11.4 Future disease risks. 12 Laboratory Procedures in Disease Diagnosis and Control. 12.1 Examination on site. 12.2 Submitting a sample to the laboratory. 12.3 Initial examination. 12.4 Euthanasia. 12.5 Detailed external examination. 12.6 Blood sampling. 12.7 Detailed internal examination. 12.8 Laboratory tests. 12.9 Diagnosis. 12.10 Post mortem equipment. Fish Names Cited in Text. Glossary of Terms. Index.

Pollutant-induced effects on immunological and physiological interactions in aquatic host–trematode systems: implications for parasite transmission

Under conditions of pollution both host and parasite are susceptible to the pathogenic effects of toxicants, which in turn may result in detrimental changes to their immunological and physiological processes. Digenetic trematodes, which encompass species of both medical and economic importance, possess complex life cycles and are common parasites of both vertebrates and molluscs. The combined stress induced by pollution and parasitism influences the physiology of the host which can have implications not only on host survival but also on the functional biology of resident parasite populations. The present paper reviews the effects of pollutants on the immunology and physiology in both vertebrate and molluscan host-trematode systems and the implications for parasite transmission.

Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda: Gorgoderidae)

Abstract Hoole D. and Mitchell J.B. 1981. Ultrastructural observations on the sensory papillae of juvenile and adult Gorgoderina vitelliloba (Trematoda : Gorgoderidae). International Journal for Parasitology 11 : 411–417. Ultrastructural observations have been made on the juvenile and adult stages of Gorgoderina vitelliloba from Rana temporaria . Four types of sensory papillae occur; button, rosette, ciliated and domed. Button papillae, which contain a ciliary-rootlet but lack a cilium, occur on the oral sucker, dorsal preacetabular surface and the lateral margins of the fluke. Scanning electron microscopical observations reveal that the tegumental protuberances of the papilla are transformed from a spiked or conical appearance in juvenile flukes to a rounded form in adult flukes. Rosette papillae, which also contain a rootlet, occur on the lip of the ventral sucker of both juvenile and adult flukes. Ciliated papillae only occur on the oral sucker of juvenile flukes. Domed papillae, which contain a large area of electron-dense material, occur on the internal surface of the ventral sucker of both juvenile and adult flukes. The functions of papillae and their possible role in the migration of the parasite are discussed.

Ultrastructural studies on the cellular response of fish hosts following experimental infection with the plerocercoid of Ligula intestinalis (Cestoda: Pseudophyllidea)

With the exception of gudgeon ( Gobio gobio ) infection of cyprinid fish with the plerocercoid of Ligula intestinalis is associated with a host-tissue response. The nature and specificity of this response has been investigated using transplantation techniques. In roach there is an intense cellular response to implanted Sepharose, Spurrs resin and L. intestinalis , irrespective of donor host species. However, tegument damage only occurs in gudgeon- Ligula and cultured ro&ch- Ligula which has been exposed to gudgeon-plasma. L1 and L2 cell types predominate within the cellular response. Once the host leucocytes have breached the tegument, they migrate over the basal lamina and penetrate into the sub-tegumental region. In gudgeon an intense cellular attack occurs against Sepharose, Spurrs resin, ro&ch- Ligula and cultured gudgeon- Ligula which had been implanted directly or exposed to roach plasma. Tegument damage only occurs in the latter. In contrast, neither direct implantation of gudgeon- Ligula nor cultured roach- Ligula which has been exposed to gudgeon plasma evokes a cellular response. It is suggested that in these two instances, as in natural infections of gudgeon, protective host proteins may be absorbed onto the surface of the parasite.

Oxidative burst and nitric oxide responses in carp macrophages induced by zymosan, MacroGard(®) and selective dectin-1 agonists suggest recognition by multiple pattern recognition receptors.

β-Glucans are glucose polymers that are found in the cell walls of plants, bacteria, certain fungi, mushrooms and the cell wall of bakers yeast. In mammals, myeloid cells express several receptors capable of recognizing β-glucans, with the C-type lectin receptor dectin-1 in conjunction with Toll-like receptor 2 (TLR2), considered key receptors for recognition of β-glucan. In our studies to determine the possible involvement of these receptors on carp macrophages a range of sources of β-glucans were utilized including particulate β-glucan preparations of bakers yeast such as zymosan, which is composed of insoluble β-glucan and mannan, and MacroGard(®), a β-glucan-based feed ingredient for farmed animals including several fish species. Both preparations were confirmed TLR2 ligands by measuring activation of HEK293 cells transfected with human TLR2 and CD14, co-transfected with a secreted embryonic alkaline phosphatase (SEAP) reporter gene. In addition, dectin-1-specific ligands in mammals i.e. zymosan treated to deplete the TLR-stimulating properties and curdlan, were monitored for their effects on carp macrophages by measuring reactive oxygen and nitrogen radicals production, as well as cytokine gene expression by real-time PCR. Results clearly show the ability of carp macrophages to strongly react to particulate β-glucans with an increase in the production of reactive oxygen and nitrogen radicals and an increase in cytokine gene expression, in particular il-1β, il-6 and il-11. We identified carp il-6, that was previously unknown. In addition, carp macrophages are less, but not unresponsive to selective dectin-1 agonists, suggesting recognition of β-glucans by multiple pattern recognition receptors that could include TLR but also non-TLR receptors. Candidate receptors for recognition of β-glucans are discussed.

Inflammatory interactions in fish exposed to pollutants and parasites: a role for apoptosis and C reactive protein

Although previous studies have highlighted the inflammatory responses of fish infected with parasites and exposed to pollutants, very little is known about how these two stressors interact within the fish. In this review, which also contains original data, the effect of these two parameters on the fish inflammatory response is assessed and, in particular, the role of apoptosis and the acute phase protein, C reactive protein, is evaluated. In Cyprinus carpio exposed to 0.5 mg NH4+ l(-1) or 0.1 mg Cd2+ l(-1) and experimentally infected with the blood fluke, Sanguinicola inermis, the pollutant type and the order in which the fish experiences the parasite and toxicant, significantly affects the ultrastructural appearance and cellular content of the pronephros and thymus. This is reflected in the intensity of infection where the pollutant appears to have less effect on an established infection. Both stressors, pollutant and infection, may mediate their effects via the endocrine system. Studies have revealed that cortisol at 100 ng ml(-1) is able to induce apoptosis in pronephric cells of carp and that an increase in apoptosis is associated with an increase in phagocytosis in this immune organ. In addition, C reactive protein, which is used as a biomarker of the inflammatory response in humans and other mammals, is evaluated as a possible indicator of physiological states in fish exposed to pathogens and pollutants.

Dietary β-glucan stimulate complement and C-reactive protein acute phase responses in common carp (Cyprinus carpio) during an Aeromonas salmonicida infection

The effect of β-glucans as feed additive on the profile of C-reactive protein (CRP) and complement acute phase responses was studied in common carp Cyprinus carpio after exposition to a bacterial infection with Aeromonas salmonicida. Carp were orally administered with β-glucan (MacroGard®) for 14 days with a daily β-glucan intake of 6 mg per kg body weight. Fish were then intraperitoneally injected with either PBS or 1 × 10⁸ bacteria per fish and sampled at time 0, 6, 12, 24, 48, 72, 96 and 120 h post-injection (p.i.) for serum and head kidney, liver and mid-gut tissues. CRP levels and complement activity were determined in the serum samples whilst the gene expression profiles of CRP and complement related genes (crp1, crp2, c1r/s, bf/c2, c3 and masp2) were analysed in the tissues by quantitative PCR. Results obtained showed that oral administration of β-glucan for 14 days significantly increased serum CRP levels up to 2 fold and serum alternative complement activity (ACP) up to 35 fold. The bacterial infection on its own (i.e. not combined with a β-glucan feeding) did have significant effects on complement response whilst CRP was not detectably induced during the carp acute phase reaction. However, the combination of the infection and the β-glucan feeding did show significant effects on both CRP and complement profiles with higher serum CRP levels and serum ACP activity in the β-glucan fed fish than in the control fed fish. In addition, a distinct organ and time dependent expression profile pattern was detected for all the selected genes: a peak of gene expression first occurred in the head kidney tissue (6 h p.i. or 12 h p.i.), then an up-regulation in the liver several hours later (24 h p.i.) and finally up- or down-regulations in the mid-gut at 24 h p.i. and 72 h p.i. In conclusion, the results of this study suggest that MacroGard® stimulated CRP and complement responses to A. salmonicida infection in common carp.

Ligula intestinalis (L.) (Cestoda: Pseudophyllidea): polarization of cyprinid leucocytes as an indicator of host-and parasite-derived chemoattractants

Freshly isolated pronephric leucocytes from roach, Rutilus rutilus and gudgeon, Gobio gobio were exposed to extracts of plerocercoids of Ligula intestinalis from these two cyprinid fish. Addition of the extracts or an increase in incubation temperature from 10 to 20 degrees C induced polarization of neutrophils and L1 granulocytes. Cells were transformed from their typical spherical shape to elongate forms possessing a ruffled leading edge. Extracts obtained from gudgeon-Ligula stimulated polarization of both roach and gudgeon leucocytes at 10 and 20 degrees C. In contrast, extracts from roach-Ligula, whilst having little effect at 10 degrees C, suppressed temperature-induced polarization of leucocytes at 20 degrees C. Addition of serum to all the essays enhanced polarization and abolished the roach-Ligula-induced suppression. It is suggested that leucocyte chemoattractants are present in Ligula from roach and gudgeon and only parasites from the former host contain an inhibitor of polarization. In addition, host-derived factors possibly complement, may be involved in leucocyte chemoattraction.

Ligula intestinalis (Cestoda: Pseudophyllidea): An ultrastructural study on the cellular response of roach fry, Rutilus rutilus

Abstract Ultrastructural studies have shown that the plerocercoid larva of Ligula intestinalis elicits a cellular response in the fry of roach Rutilus rutilus . In some fish this response consists of intact L1 and L2 cell types (macrophage and neutrophil respectively?). In the majority of fish however, host cell disintegration has occurred. Two leucocyte types not previously observed in established infections are described. Parasite damage occurs in the form of microthrix loss and the release of tegumental protuberances containing mitochondria. However it is believed that plerocercoids survive any initial damage that may occur.

Feeding common carp Cyprinus carpio with β-glucan supplemented diet stimulates C-reactive protein and complement immune acute phase responses following PAMPs injection.

The effect of β-glucan as a feed additive on the serum and gene profile of C-reactive protein (CRP) and complement acute phase responses was ascertained in common carp Cyprinus carpio. In addition effects of subsequent intraperitoneal injections of pathogen-associated molecular patterns (PAMPs), i.e. LPS or poly(I:C), to mimic bacterial or viral infection respectively, were studied. Carp were first orally fed with β-glucan (MacroGard®) with a daily β-glucan intake of 6 mg per kg body weight or with control food for 25 days and then injected with PBS containing either LPS (4 mg/kg) or poly(I:C) (5 mg/kg) or PBS alone. Fish were sampled during the 25 days of the feeding period and up to 7 days post-PAMPs injections for serum and liver, head kidney and mid-gut tissues. Oral administration of β-glucan for 25 days significantly increased serum CRP levels and alternative complement activity (ACP). In addition, the subsequent LPS and poly(I:C) challenges significantly affected CRP and complement related gene expression profiles (crp1, crp2, c1r/s, bf/c2, c3 and masp2), with the greatest effects observed in the β-glucan fed fish. However, in fish fed β-glucan the PAMPs injections had less effects on CRP levels and complement activity in the serum than in control fed fish, suggesting that the 25 days of β-glucan immunostimulation was sufficient enough to reduce the effects of LPS and poly(I:C) injections. Results suggest that MacroGard® stimulated CRP and complement responses to PAMPs immunological challenges in common carp thus highlighting the beneficial β-glucan immunostimulant properties.