Recently an increase in the population of wild boars (Sus scrofa) in Europe has been observed. This is important from a zoonotic perspective because it influences directly on the spread of many diseases. For the first time, an extensive survey on the prevalence of Leptospira infections in Polish wild boars was performed. During the hunting season 2012–2014, 3621 blood samples from wild boars were collected. The animals originated from different geographical areas across Poland. Serum samples were tested by a microscopic agglutination test (MAT) for the presence of specific antibodies to the following Leptospira serovars: Icterohaemorrhagiae, Grippotyphosa, Sejroe, Tarassovi, Pomona, Canicola, Bratislava, Autumnalis, Hardjo and Ballum. Antibody titers to all Leptospira serovars except serovar Ballum were found in 377 serum samples (10.4 %). The highest number of seropositive wild boars was found in the south-eastern part of Poland and in highly urbanized areas such as Silesia and Łódź. The relatively high prevalence of Leptospira infections in wild boars may constitute a threat to hunters and people having contact with forest lakes or marshlands. The results also indicate that an increasing population of wild boar living close to borders of cities may create additional risk for inhabitants in large urban areas.

In this study, we investigated the clinical response, viral shedding, transmissibility, pathologic lesions, and tropism of HPAIV Gs/Gd H5N8 subtype (clade 2.3.4.4b), following experimental infection of three groups of captive mallards (Anas platyrhynchos): (i) fully susceptible, (ii) pre-exposed to low pathogenic avian influenza virus (LPAIV) H5N1 subtype, and (iii) pre-exposed to LPAIV H3N8 subtype. Infection of naïve mallards with HPAIV H5N8 resulted in ~60% mortality, neurological signs, abundant shedding, and transmission to contact ducks, who also became sick and died. High amounts of viral RNA were found in all collected organs, with the highest RNA load recorded in the brain. The IHC examinations performed on tissues collected at 4 and 14 days post-infection (dpi) revealed tropism to nervous tissue, myocardium, respiratory epithelium, and hepatic and pancreatic cells. The mallards pre-exposed to LPAIV H5N1 and challenged with HPAIV H5N8 were asymptomatic and showed a significant reduction of viral RNA shedding, yet still sufficient to cause infection (but no disease) in the contact ducks. The AIV antigen was not detected in organs at 4 and 14 dpi, and microscopic lesions were mild and scarce. Similarly, mallards previously inoculated with LPAIV H3N8 remained healthy after challenge with HPAIV H5N8, but viral RNA was detected in large quantities in swabs and organs, particularly in the early phase of infection. However, in contrast to mallards from group I, the IHC staining yielded negative results at the selected timepoints. The virus was transmitted to contact birds, which remained symptomless but demonstrated low levels of viral RNA shedding and mild- to moderate tissue damage despite negative IHC staining. The results indicate that naïve mallards are highly susceptible to HPAIV H5N8 clade 2.3.4.4b and that homo- and heterosubtypic immunity to LPAIV can mitigate the clinical outcomes of infection.

Introduction: The broiler chicken digestive tract microbiome maintains the bird’s immunity. Its composition has been shown to be important not only for the immune system but also for the gastrointestinal function and productivity of broiler chickens. If the microbiome is populated by supplementation with Lactobacillus, Pediococcus and Saccharomyces spp. – microorganisms with probiotic properties and alternatives to antibiotics – the immune system is stimulated. The use of probiotic supplements in the broiler production cycle can boost bird immunity and prevent adenovirus infection. The resilience of broiler chickens in different feeding schemes including supplementation with these microorganisms was assessed. Material and Methods: Four groups of Ross 308 chickens vaccinated on the standard scheme were investigated over 42 days. Group P received probiotics, prebiotics and vitamins; group AO received antibiotics; group P&AO received probiotics, prebiotics, vitamins and antibiotics; and the control group C received none of these. The birds’ immunocompetence against common viral poultry pathogens and their immune response to an experimental challenge with a field strain of infectious bronchitis was evaluated by ELISA and production parameters were recorded. Results: Mortality was only observed in the control group and was 10%. All birds from the P, P&AO and AO groups responded to the challenge as would be expected of appropriately immunised chickens. Conclusion: The obtained results indicated that supplementation with synbiotic products and vitamins can enhance broiler chicken immunity and result in better production parameters.

African swine fever (ASF) is a lethal hemorrhagic disease of Suidae, i.e., domestic pigs and wild boars. The disease was introduced to Poland in 2014 and is now present in the wild boar population. Appropriate ASF prevention requires further research for answers to fundamental questions about the importance of vectors in virus transmission, the impact of environmental factors on the presence of ASFV in wild boar habitats, and the role of survivors as potential virus carriers and their part in the potential endemicity of ASF. In order to analyze the changes in the molecular and serological prevalence of ASFV in wild boar population in Poland, real-time PCR and ELISA/IPT tests were conducted. In the analyzed period (2014–2020), most of the ASF-positive wild boars were molecular/virus-positive, however, over the years the percentage and the number of seropositive animals has increased. At the beginning of the epidemic, the disease was limited to a small area of the country. Since then, it has spread to new provinces of Poland. From the beginning and until today, most notifications of ASF-positive wild boars were for carcasses (passive surveillance), however, the number of serologically positive animals is still increasing. Despite the fact that notifications of ASF outbreaks are still being received near the eastern border of Poland, the old ASF area seems to be limited mainly to ASF serologically positive animals, which may indicate the beginning of ASF endemicity in Poland.

Leptospira spp. infect humans and a wide range of domestic and wild animals, but certain species such as small rodents and red foxes (Vulpes vulpes) play a particular role as reservoirs and transmission of leptospirosis as they easily adapt to many habitats including human environments. To investigate the significance of red foxes in the epidemiology of leptospirosis in Poland, a seroprevalence survey was conducted. During the 2014–2015 hunting season, blood samples of 2134 red foxes originating from the central-eastern part of Poland were collected. Serum samples were tested by a microscopic agglutination test for the presence of specific antibodies to Leptospira serovars Icterohaemorrhagiae, Grippotyphosa, Sejroe, Tarassovi, Pomona, Canicola, Hardjo, Ballum, Australis, Bataviae, Saxkoebing and Poi. Antibodies to at least one serovar were detected in 561 sera (26.3%). The highest seroprevalence was found in the Subcarpathia (41.6%) and Warmia-Masuria (40.3%) provinces. Antibodies were mainly directed against serovars Poi (12.4%), Saxkoebing (11.3%), and Sejroe (6.0%). Exposure of red foxes to certain Leptospira serovars seems to be common in central and eastern Poland. In addition, the high prevalence of antibodies against Leptospira spp. in foxes may indicate a potential risk of infection for humans and other species coming into contact with these animals.