Carp oedema virus (CEV) is a relatively understudied poxvirus. It exhibits an affinity for gill and skin epithelial cells. Investigations were conducted into selected aspects of CEV biology, with a focus on determining cell and tissue tropism of CEV, acquiring gene sequences and updating CEV tests in fish tissues.

Introduction Carp oedema virus (CEV) is a relatively understudied poxvirus. It exhibits an affinity for gill and skin epithelial cells. Investigations were conducted into selected aspects of CEV biology, with a focus on determining cell and tissue tropism of CEV, acquiring gene sequences and updating CEV tests in fish tissues. Material and Methods A total of 238 common carp tissue samples from nine aquaculture farms were analysed. The study evaluated the efficacy of intermediate detection of CEV by real-time PCR and in situ hybridisation. The genes encoding protein P4a were sequenced, analysed and aligned in a phylogenetic tree using a molecular evolution model. Results In situ hybridisation revealed the necessity to validate the Centre for Environment, Fisheries and Aquaculture Science protocols for sampling for CEV detection and to use the tissues for which the virus has the highest tropism, namely the skin and kidneys, rather than solely the gills. The level of genetic variability was determined, and it was shown that CEV mutates systematically. The creation of two distinct phylogenetic clades confirms certain strains’ description as Polish isolates. Conclusion Determining the localisation of CEV genetic material in organs and tissues is pivotal for shaping the World Organisation for Animal Health guidelines. The utility of molecular diagnostics has been demonstrated in the skin and kidney of carp, in addition to the gills, impelling their inclusion in diagnostic protocols. The clusters identified in the phylogenetic tree offer valuable insights for developing the current PCR primers. The prevalence of CEV infection in aquaculture, juxtaposed with its notably lower detection in wild fish, underscores the significance of mandatory molecular diagnostic testing for CEV in carp farming.

Herpesviruses are common agents in animals of the aquatic environment. They infect many species of fish but only lead to disease in one or two species. Nevertheless, infected fish without clinical symptoms can actively transfer infectious agents to disease-susceptible species. The aim of the study was to identify and prove the natural presence of different herpesviruses.

Herpesviruses are common agents in animals of the aquatic environment. They infect many species of fish but only lead to disease in one or two species. Nevertheless, infected fish without clinical symptoms can actively transfer infectious agents to disease-susceptible species. The aim of the study was to identify and prove the natural presence of different herpesviruses. Material and Methods Koi, Nile tilapia, grass carp, goldfish and crucian carp were infected with a herpesvirus isolate 99% identical to goldfish herpesvirus (GHV) or cyprinid herpesvirus 2 (CyHV-2) obtained from crucian carp. Before and after infection, samples were collected non-lethally at different time points from all five fish species to identify and evaluate the replication of viruses naturally infecting the fish as well as the CyHV-2 experimentally infecting them. Gill swabs and separated leukocytes were subjected to PCR and the results compared. Results These samples yielded DNA of koi herpesvirus (KHV, also referred to as CyHV-3), GHV and a new herpesvirus. While Asian-lineage CyHV-3 DNA was detected in samples from crucian carp and goldfish, CyHV-2 DNA was found in samples from koi and tilapia. A new, hitherto unknown herpesvirus was identified in samples from grass carp, and was confirmed by nested PCR and sequence analysis. The survival rates were 5% for grass carp, 30% for tilapia, 55% for crucian carp, 70% for koi and 100% for goldfish at 20 days post infection. Evolutionary analyses were conducted and five clusters were visible: CyHV-1 (carp pox virus), CyHV-2 with sequences from koi and tilapia, CyHV-3 with sequences from crucian carp and goldfish, probable CyHV-4 from sichel and a newly discovered herpesvirus – CyHV-5 – from grass carp. Conclusion The results obtained with the molecular tools as well as from the animal experiment demonstrated the pluripotency of aquatic herpesviruses to infect different fish species with and without visible clinical signs or mortality.

Nontuberculous mycobacteria (NTM) are increasingly recognised as causative agents of opportunistic infections in humans for which effective treatment is challenging. There is very little information on the prevalence of NTM drug resistance in Poland. This study was aimed to evaluate the susceptibility to antibiotics of NTM, originally isolated from diseased ornamental fish. A total of 99 isolates were studied, 50 of them rapidly growing mycobacteria (RGM) (among which three-quarters were Mycobacterium chelonae, M. peregrinum, and M. fortuitum and the rest M. neoaurum, M. septicum, M. abscessus, M. mucogenicum, M. salmoniphilum, M saopaulense, and M. senegalense). The other 49 were slowly growing mycobacteria (SGM) isolates (among which only one was M. szulgai and the bulk M. marinum and M. gordonae). Minimum inhibitory concentrations for amikacin (AMK), kanamycin (KAN), tobramycin (TOB), doxycycline (DOX), ciprofloxacin (CIP), clarithromycin (CLR), sulfamethoxazole (SMX), isoniazid (INH) and rifampicin (RMP) were determined. The majority of the isolates were susceptible to KAN (95.95%: RGM 46.46% and SGM 49.49%), AMK (94.94%: RGM 45.45% and SGM 49.49%), CLR (83.83%: RGM 36.36% and SGM 47.47%), SMX (79.79%: RGM 30.30% and SMG 49.49%), CIP (65.65%: RGM 24.24% and SGM 41.41%), and DOX (55.55%: RGM 9.06% and SGM 46.46%). The majority were resistant to INH (98.98%: RGM 50.50% and SGM 48.48%) and RMP (96.96%: RGM 50.50% and SGM 46.46%). The drug sensitivity of NTM varies from species to species. KAN, AMK, CLR and SMX were the most active against RGM isolates, and these same four plus DOX and CIP were the best drugs against SGM isolates.

Nontuberculous mycobacteria (NTM) are increasingly recognised as causative agents of opportunistic infections in humans for which effective treatment is challenging. There is very little information on the prevalence of NTM drug resistance in Poland. This study was aimed to evaluate the susceptibility to antibiotics of NTM, originally isolated from diseased ornamental fish.

Many consumers seek long-ripening meat products. The availability of these highly distinctive cured pork varieties is continuously expanding and their safety should be subject to monitoring. One of potentially harmful substances in these products is histamine. The presence of this toxic amine is reported in many countries, even in high concentrations. However, the EU has not regulated the permissible histamine content in meat, in a situation at odds with that of regulated fish and fish products. This study established the usefulness of biogenic amine testing in long-ripening pork and furnished indicative concentrations potential useful as a background for future research in preparation for EU regulative intervention. A total of 97 samples of long-ripening meat products untreated by heat were bought from various shops in the Puławy and Lublin regions of Poland and tested for the presence of histamine using high-performance liquid chromatography with diode array. The histamine concentration ranged from below limit of detection to 346.64 mg/kg, where 3.47 mg/kg was the lowest in a positive sample. Histamine was detected in 48 samples (49.5%). The maximum amount of histamine was identified in dry ham and the minimum in traditional salami. The results of this study suggest that testing meat products for biogenic amines should be a very good indicator of the food safety of long-ripening meats. In half of the tested products, levels of biogenic amines potentially toxic to consumers were determined.

Many consumers seek long-ripening meat products. The availability of these highly distinctive cured pork varieties is continuously expanding and their safety should be subject to monitoring. One of potentially harmful substances in these products is histamine. The presence of this toxic amine is reported in many countries, even in high concentrations. However, the EU has not regulated the permissible histamine content in meat, in a situation at odds with that of regulated fish and fish products. This study established the usefulness of biogenic amine testing in long-ripening pork and furnished indicative concentrations potential useful as a background for future research in preparation for EU regulative intervention.

Koi herpesvirus (KHV) has infected farmed common carp in Poland clinically and asymptomatically since 2004. The role of non-carp species as vectors of virus transmission is well known except for in the case of KHV. The aim was to better understand this virus’ infection and transmission pathways in common carp, looking at the potential vector role of fishes kept with them.

Koi herpesvirus (KHV) has infected farmed common carp in Poland clinically and asymptomatically since 2004. The role of non-carp species as vectors of virus transmission is well known except for in the case of KHV. The aim was to better understand this virus’ infection and transmission pathways in common carp, looking at the potential vector role of fishes kept with them. Eight species were experimentally infected with KHV by immersion in a suspension at 20°C ±1 and transferred to a tank after 45 minutes. Specimens were euthanised at intervals up to 56 days post infection (dpi) and tissue was examined for KHV DNA. Surviving infected fishes were introduced at intervals, each time into a separate tank, to naïve common carp for experimental infection. These were observed daily for symptoms, sacrificed along with controls after three months, and dissected to provide tissue samples. Also fish from 14 species collected from a farm with a history of KHV were sampled from 3 to 22 months after disease was confirmed. Organ sections from single fish were collected in a single tube. Viral DNA was detected in tench and roach samples up to 49 dpi, but in three-spined stickleback and stone maroko samples only up to 14 dpi. Transmission of KHV to naïve carp occurred after cohabitation. KHV DNA was detected in three fish species three months after the farm outbreak. We confirmed that grass and Prussian carp, tench, roach, and brown bullhead can transfer the virus to naïve common carp.

Introduction: The aim of this study was to evaluate the prevalence of Clostridium botulinum and Clostridium perfringens in food samples purchased from Polish producers. Material and Methods: The analyses were performed on 260 food samples collected in Lublin and Subcarpathian regions: 56 of smoked meat, 21 of pork meat, 20 of dairy products, 26 of vegetable and fruit preserves, 40 of ready-to-eat meals, 27 of fish preserves, and 70 of honey collected directly from apiaries. Results: C. botulinum strains were isolated from 2.3% (6/260) of samples and the isolates were classified as toxin types A (4/260) and B (2/260). C. perfringens strains were isolated from 14% (37/260) of samples. All the isolates were classified as toxin type A, 28 of them were able also to produce α toxin and 9 - β2 toxin. Conclusion: On the basis of the obtained results it could be suggested that risk assessment, especially regarding the entire honey harvesting process, should be provided in order to ensure the microbiological safety of the products to be consumed by infants and people with a weakened immune system.

Introduction: The aim of this study was to evaluate the prevalence of Clostridium botulinum and Clostridium perfringens in food samples purchased from Polish producers. Material and Methods: The analyses were performed on 260 food samples collected in Lublin and Subcarpathian regions: 56 of smoked meat, 21 of pork meat, 20 of dairy products, 26 of vegetable and fruit preserves, 40 of ready-to-eat meals, 27 of fish preserves, and 70 of honey collected directly from apiaries. Results: C. botulinum strains were isolated from 2.3% (6/260) of samples and the isolates were classified as toxin types A (4/260) and B (2/260). C. perfringens strains were isolated from 14% (37/260) of samples. All the isolates were classified as toxin type A, 28 of them were able also to produce α toxin and 9 - β2 toxin. Conclusion: On the basis of the obtained results it could be suggested that risk assessment, especially regarding the entire honey harvesting process, should be provided in order to ensure the microbiological safety of the products to be consumed by infants and people with a weakened immune system.