Can fish scales be a potential source of pathogenic microorganisms for human health

Bacterial zoonoses of fishes: A review and appraisal of evidence for linkages between fish and human infections

Comparison of intestinal bacterial communities in asymptomatic and diseased Asian seabass (Lates calcarifer) with chronic enteritis and mixed bacterial infections

Dhanusha is one of the leading fish producing districts in Nepal and the fish farming is increasing in the district to establish the district as a ‘Fisheries center’. However, with the increasing fish farming and intensity, a number of diseases find their way to the farm which may hinder the progress of fish farming. Present study was carried out to assess the fish farming practices and the disease occurrence across the fish farms of Dhanusha district. Questionnaire-based personal interviews were conducted with 64-fish farmers selected from all over the district using simple random sampling. Majority of the respondents were males (89.1%), in the active age group of 30-50 years (71.9%), with average experience of more than 15 years (39%) in fish farming. The widely adopted farming system was Carp polyculture, however, some of the farmers also culture other species like Pangas, African catfish, Rupchand, Puntius etc. Only earthen ponds were common with water depths of 5-7 ft (54.7%). Majority of the respondents relied on private hatcheries (34.4%) for fish seeds and the most common stocking size was fingerlings (42.2%) and fry (29.7%). The major source of information and technical support for the farmers were successful farmers (82.8%) and government offices (73.4%). Approximately 65.6% of the farmers had received trainings on fish production and disease management. The most common feed materials were mustard oil cake (100%); rice bran (96.9%) and commercial pellet feed (54.7%). Cattle dung (87.5%); poultry manure (28.1%) and Urea/DAP (95.3%) were the major fertilizers used by the farmers. The most prevalent fish disease was Argulosis (96.9%), Lernaea (90.6%) and EUS (85.9%), but asphyxiation (82.8%) caused the reportedly highest mortality of 346.1±305.5 Kg/ha. Similarly, the most susceptible species to disease was Naini (65.6%) followed by silver carp (49.0%) and bighead carp (34.0%), while the least infected species was Grass carp (0.8%). Winter (70.3%) was reported to be the main season for the occurrence of fish diseases in Dhanusha district. The average B/C ratio in pond aquaculture in the study area was 1.36.

The aim of this study is to understand molecular characterization and antimicrobial resistance of diarrheagenic and nondiarrheagenic E. coli from healthy and diseased farm fish from Cypriniformes order. A total of 516 healthy and diseased farmed fish samples belong to Cypriniformes order were collected from various regions of Punjab and screened for E. coli. Biochemical tests and PCR confirmation were conducted using the 16S rRNA and UspA genes. DEC was examined through PCR using different virulence genes. All isolates were tested for various antibiotics using the disk diffusion method. The phenotypic and genotypic resistances of Extended-spectrum β-lactamases (ESBLs) were investigated. A Chi-square test was performed to compare the prevalence of E. coli, virulence genes, and ESBLs genes with a significance level of P ≤ 0.05. Out of the total fish samples, 16.66% and 36.57% of E. coli strains were confirmed through biochemical tests and PCR, respectively. The DEC pathotypes were recorded in 30% and 62.02% of isolates from healthy and diseased fish, respectively. A higher rate of 19.37% of EAEC pathogroup was observed in both healthy and diseased fish, while the EIEC pathogroup was only observed in diseased fish at a rate of 10.07%. The significance (P ≤ 0.05) was observed among the virulence genes. The highest resistance rates among diarrheagenic and non-diarrheagenic strains were observed with tetracycline, amoxicillin, and ceftazidime. A higher prevalence of CTX-M (56.81%) and TEM (43.18%) was recorded in DEC pathotypes, while blaSHV was not detected. The high prevalence of DEC E. coli, and the production of ESBLs, indicate unhygienic practices and the misuse of antibiotics in fish farms.

Seafoods are consumed as raw, semi-cooked or cooked in different societies and they are valuable animal protein sources. They are suitable foods for growing of microorganisms because of their high water and protein contents, near neutral pH value. Pathogen microorganisms cause adverse effect (causing disease) on human body. Some pathogens are only effective in human, some species are only in animal while some of harmful to both animal and human. Pathogen microorganisms and their toxins are dangerous for people consuming these foods especially as raw or semi-cooked. Pathogen microorganisms could be observed in seafoods caught newly fresh and also could be transmitted by cross contamination from human or substances added during marketing, transporting, heading, eviscerating or processing. The type and natural habitats of seafoods pathogens are so variable. Staphlococcus aureus, Salmonella spp., Clostridium perfringens, Clostridium botulinum, Vibrio parahaemolyticus, Vibrio cholerae, Vibrio vulnificus, Listeria monocytogenes are among the some seafood pathogen microorganism. Seafood toxins formed by algae and bacteria, cause huge economic losses. This study provide information concerning with seafood pathogens and their toxins and food poisoning caused by them.

As aquaculture production and the consumption of aquaculture products increase, the possibility of contracting zoonotic infections from either handling or ingesting these products also increases. The principal pathogens acquired topically from fish or shellfish through spine/pincer puncture or open wounds are Aeromonas hydrophila, Edwardsiella tarda, Mycobacterium marinum, Streptococcus iniae, Vibrio vulnificus and V. damsela. These pathogens, which are all indigenous to the aquatic environment, have also been associated with disease outbreaks in food fish. Outbreaks are often related to management factors, such as the quality and quantity of nutrients in the water and high stocking density, which can increase bacterial loads on the external surface of the fish. As a result, diseased fish are more likely to transmit infection to humans. This review provides an account of human cases of zoonoses throughout the world from the principal zoonotic pathogens of fish and shellfish.

The article substantiates the importance, the principle of the action of probiotics, the purpose of their application, the mechanisms of therapeutic and prophylactic action, the effectiveness of the use of probiotic drugs and the feasibility of their application. It is known that the ideal probiotic should be of the origin of the body for which it will be used, be resistant to acids and bile, capable of adhesion and colonization in the intestinal tract or other ecosystems, to produce antibiotic substances, to prevent the development of cariogenic and pathogenic microorganisms, to be safe for use in products and clinics and have a well-defined and validated clinical trial with a positive effect on human or animal health. Positive effects of probiotics are manifested in reducing the duration of toxic effects or increasing the resistance to action of pathogens. The components of probiotics are representatives of normal microflora, and therefore the main mechanisms that determine their degree and direction of healing effect on the host organism are colonization resistance and immunomodulatory ability, regulation of metabolic processes and detoxification action, anti-carcinogenic activity. These functions are implemented through enzymatic, vitamin-synthesizing, antagonistic and adhesive activity. Strains of bacteria of probiotics produce a wide range of digestive enzymes - amylase, lipase, protease, pectinase, endoglucanose and phytase. Important impetus for the use of probiotics was the recommendations and requirements for limiting the use of antibiotics in livestock used for therapeutic purposes. The adverse effect of fodder antibiotics is the appearance of diarrhea in animals, as well as the risk of the formation and rapid reproduction of antibiotic-resistant bacteria such as Salmonella spec. Probiotic drugs are most often used in the treatment of a number of pathological conditions occurring against the background of disturbed normal microflora of the human body. Probiotic drugs can also be used for the prevention and treatment of major dental diseases: caries, chronic generalized periodontitis of catarrhal gingivitis, aphthous stomatitis. In experimental studies, it has been shown that intestinal microbiota, interacting with the host organism, can increase the number of osteoclasts, for example, in the femoral bones, and, consequently, decrease their density, which confirms the growth of catabolic activity of bones under conditions of intestinal microbiota dysbiosis. Recently, for the normalization of metabolic processes in the organism of farm animals and poultry began to use probiotic drugs, which, in essence, are a living microbial supplement to the feed and have a positive effect on the body through improving its intestinal microbial balance. Probiotics, as environmentally safe drugs, help to reduce the man-caused and microbial stress on the animals organism in conditions of intensive production of livestock products, which prevents the development of many pathologies in animals, and, consequently, in humans. Probiotic products should be characterized by a pronounced antagonistic activity to a wide range of pathogenic and opportunistic microorganisms, to be strong immunomodulators and to produce bacteriocin and enzymes. The bacteria that are part of the probiotics should remain viable when passing through the gastrointestinal tract of animals and poultry, as well as in the production of feed (for example, in granulation). At present, the effectiveness of the use of probiotics for stimulation of growth intensity and prevention of diseases of young animals, increase of productivity and quality of received products, prevention of gynecological diseases in cows, prevention of viral diseases of bees and increase of their productivity, reduction of parasitic diseases in fish and increase of efficiency of fish farming is substantiated. A promising direction for improving probiotics is the development of complex drugs, which include different types of bacterial cultures that complement each other by specific activity and the effect on opportunistic microorganisms.

Aquaculture production in Kenya has been growing exponentially as a Government initiative to meet population nutritional requirements and food security. Unfortunately factors exist such as fish infection and disease that work against the health and survival of fish in aquaculture. This study focused on identifying bacterial pathogens present in aquaculture systems in Bungoma County and determined how the pathogens respond to commonly used antimicrobial agents. During the study, Vibrio vulnificus, Vibrio parahaemolyticus, Aeromonas hydrophila and Pseudomonas aeruginosa were recovered from farmed Nile tilapia while Aeromonas hydrophila and Streptococcus iniae were isolated from fish source pond water and fish feeds respectively. Among the bacterial isolates from Nile tilapia, Vibrio vulnificus and Aeromonas hydrophila were resistant to ampicillin while Vibrio parahaemolyticus and Pseudomonas aeruginosa were resistant to cefuroxime and ampicillin. Aeromonas hydrophila recovered from pond water were found to be resistant to both ampicillin and cefuroxime whereas, Streptococcus iniae isolated from fish feeds were observed to be resistant to ceftazidime, cefepime and nalidixic acid, which is a warning that unless we find alternative antimicrobial agents the aquaculture industry is likely to collapse. When the bacterial isolates were subjected to PCR, all five bacterial pathogens isolated from fish, pond water and fish feeds were found to contain blaTEM gene amplified at 424bp.

Fish diseases are one of the primary challenges faced by fish farmers, including tilapia fish farmers using tarpaulin ponds in the village of Kramajaya, West Lombok. Fish diseases can lead to significant losses in the fish farming business. Therefore, education on the management of fish diseases is essential to assist farmers in safeguarding their fish stocks and ensuring the success of their aquaculture endeavors. This endeavor aims to provide education to tilapia fish farmers using tarpaulin ponds in Kramajaya village, West Lombok, regarding the management of fish diseases. The education methods employed encompass the dissemination of information about the causes, symptoms, prevention, and treatment of fish diseases, along with aquaculture practices that can help mitigate the risk of diseases. The results of this education show an improvement in the knowledge of fish farmers regarding the management of fish diseases. They become more aware of the signs of fish diseases and are capable of taking appropriate preventive measures. Furthermore, they also understand the importance of maintaining water quality and the cleanliness of tarpaulin ponds as disease prevention measures. This education also provides a better understanding of the use of medications and proper medical actions in case fish diseases occur. Consequently, fish farmers can respond more promptly and effectively to fish diseases, which, in turn, can enhance the production of tilapia fish and the overall success of their aquaculture businesses.

Knowledge of the endemic fauna of parasites in fish are of great importance, parasites could synergistically act as stressors to health of their hosts. The objectives of this study were to evaluate prevalence and effect of parasites on hematological, biochemical indices, injury of tissues and length weight relationship of Clarias, gariepinus. Water quality variables were measured and fishes were collected each seasons for examination most common parasites in infected fishes at Abbasa Fish Farm, Egypt. Results indicated that high summer water temperature was strongly associated with parasites infection. The hematological and biochemical analysis showed significant reduction in red blood cells (RBCs) count, hemoglobin (Hb) value, packed cell volume (PCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC), total protein, Albumin, Globulin and A/G ratio, while total white blood cells (WBCs) count, mean corpuscular volume (MCV), aspartate aminotransferase activity (ASAT), alanine aminotransferase activity (ALAT), urea, creatinine, uric acid and glucose were significantly increased in infested catfish. On other hands, histopathological examination of infected fish indicated, organs most affected by infection of parasites. Overall the tendencies observed in data showed the parasites have a strong effect on host fish and drifts observed for all variables showed a strong seasonal decoration.

Fish is a source of livelihood for fishermen and fish farmers especially in Nigeria and other developing countries. Fish from river and domestic ponds are widely consumed today, hence the need to conduct this study to enable monitoring and adopting control measures of parasites. The aim of this research to analyze the gastrointestinal parasites in fish from Kaduna River and selected domestic ponds in Kaduna metropolis. Results showed that 197 fishes out of the 350 examined were infected, giving an overall prevalence (56.3%) in fish from Kaduna River and selected domestic ponds. Infection was significantly higher in fishes from Kaduna River (68.0%) than in those from selected domestic ponds (27.0%). The male was 68.3% significantly higher (p < 0.05) than that of the female (23.1%) and there was significant association (p < 0.05) in the prevalence of gastrointestinal parasites and weight of fish sampled from Kaduna River and selected domestic ponds. Intestines harboured the highest number of parasites (168) than stomach and parasites identified comprised of three taxonomic groups, the nematodes were Capillaria species, Paracamallanus species, Contracaecum species and Camallanus species respectively. Cestode was Diphyllobothrium latum and Trematode was Clinostomum species. There was no significant difference (p > 0.05) of intensity and parasite load to the fish species of parasites identified from River Kaduna and selected domestic ponds. The study has revealed that different parasites in fresh water fish from Kaduna River constitutes a major threat to fish productivity than the selected domestic ponds. It is recommended that...

Tilapia health: <i>quo vadis</i>?

Chapter 14 - Biotechnological tools in diagnosis and control of emerging fish and shellfish diseases

Simple SummaryThe increasing demand for fish products has caused disease-related problems due to intense fish practices in fish farms. The fish diseases infection caused by bacteria, viruses, and parasites could lead to high fish mortality that affected the aquaculture industry. Recently, a systematic strategy to overcome fish disease problems using multi-omics platforms has been used to provide a better understanding of how to improve the resistance of fish to pathogen infection. In this review, we highlight the current multi-omics strategies such as transcriptomics, proteomics, and metabolomics to provide information regarding their molecular mechanisms of action, subsequently important in discovering potential biomarkers for various infectious fish diseases in the aquaculture system.Aquaculture is an important industry globally as it remains one of the significant alternatives of animal protein source supplies for humankind. Yet, the progression of this industry is being dampened by the increasing rate of fish mortality, mainly the outbreak of infectious diseases. Consequently, the regress in aquaculture ultimately results in the economy of multiple countries being affected due to the decline of product yields and marketability. By 2025, aquaculture is expected to contribute approximately 57% of fish consumption worldwide. Without a strategic approach to curb infectious diseases, the increasing demands of the aquaculture industry may not be sustainable and hence contributing to the over-fishing of wild fish. Recently, a new holistic approach that utilizes multi-omics platforms including transcriptomics, proteomics, and metabolomics is unraveling the intricate molecular mechanisms of host-pathogen interaction. This approach aims to provide a better understanding of how to improve the resistance of host species. However, no comprehensive review has been published on multi-omics strategies in deciphering fish disease etiology and molecular regulation. Most publications have only covered particular omics and no constructive reviews on various omics findings across fish species, particularly on their immune systems, have been described elsewhere. Our previous publication reviewed the integration of omics application for understanding the mechanism of fish immune response due to microbial infection. Hence, this review provides a thorough compilation of current advancements in omics strategies for fish disease management in the aquaculture industry. The discovery of biomarkers in various fish diseases and their potential advancement to complement the recent progress in combatting fish disease is also discussed in this review.

The aim of the study was to present the history of ichtyopathology in Poland and the main achievements of researchers who developed this discipline. The pioneer of ichtyopathological research in Poland was the ichtyologist prof. Teodor Spiczakov, founder of the first Fish Diseases Laboratory at the Jagiellonian University (JU) and initiator of fishery veterinary service. After the Second World War, dr Stanisław F. Śnieszko, a researcher from JU, established a laboratory in the United States, renamed the National Fisheries Center in 1977. In writing about the beginnings of ichthyopathology in Poland, one must also mention prof. Bronisław Kocyłowski, founder and head of the Department of Fish Diseases at PIW in Puławy and lecturer at the Warsaw University of Life Sciences (WULS) and Maria Curie Skłodowska University in Lublin. Prof. Eugeniusz Grabda also contributed to the development of ichtyopathology. He headed the Inland Fisheries Institute (IFI), Fish Disease Laboratory and the Department of Ichthyology with the Department of Fish Diseases at the Fishery Department of the Academy of Agriculture and Technology (AAT) in Olsztyn and co-founded the Department of Marine Fisheries at the Agricultural Academy and the Department of Fish Diseases in Szczecin. In Żabieniec near Warsaw, IFI established a new Ichtiohygiene Division, renamed the Division of Pathology and Fish Immunology, formerly headed by prof. Maria Studnicka and now by prof. Andrzej K. Siwicki. Veterinary inspection in Poland is conducted by the Fish Diseases Laboratory at ZHW under the substantive supervision of the National Veterinary Research Institute &amp; National Reference Laboratories at Fish Diseases Unit in Puławy, headed by prof. Jerzy Antychowicz. Currently the Unit is the National Reference Laboratory for the diagnostics of diseases of aquaculture animals, run by prof. Michal Reichert. Prof. J. Antychowicz and dr. Jan Żelazny taught for many years at the Faculty of Veterinary Medicine at the WULS in Warsaw and at AAT in Olsztyn. The Polish Academy of Sciences has a Department of Ichtiopatology and Fishery Management in Gołysz, headed by prof. Andrzej Pilarczyk, who studies the biological basis of fish farming. “Fish diseases” is a mandatory subject at faculties of veterinary medicine in Poland, and every graduate of veterinary medicine possesses a basic knowledge in this field. The Division of Fish Diseases and Biology in Lublin has been operating since 1963 and for many years was headed by prof. Maria Prost, an authority on the parasitology of fish. The current head of the Division is prof. Antonina Sopińska. The Division of Hygiene Veterinary Laboratory and Fish Diseases Laboratory (later Division of Ichtyopathology) at the Faculty of Veterinary Medicine, Wrocław University af Environmental and Life Sciences were previously headed by prof. Zbigniew Jara, and now by dr Wiktor Niemczuk. At the University of Warmia and Mazury in Olsztyn, prof. Andrzej K. Siwicki and dr Elżbieta Terech-Majewska run the Fish Disease Laboratory and Veterinary Laboratory for Diagnostics of Fish, Amphibians and Reptiles, carry out scientific research, teach and cooperate with fish farmers.