Magdalena Larska

Wildlife disease investigations require diagnostic methods capable of detecting diverse and previously unrecognized pathogens. Metagenomic next-generation sequencing (mNGS) was applied to samples from three Dorcas gazelles (Gazella dorcas osiris) affected by sudden mortality and four European bison (Bison bonasus) with respiratory disease or necrotic balanoposthitis (NBP). No dominant bacterial species was detected in gazelles. In European bison, respiratory disease was associated with Pasteurella multocida, whereas NBP samples were dominated by Porphyromonas levii and other anaerobes. Dorcas gazelle samples contained mainly Retroviridae-related sequences of undetermined pathogenic significance. Parapoxvirus-related annotations were not confirmed by PCR, suggesting non-specific or host-related sequence similarity. Macavirus-related sequences were consistent with previous PCR findings and enabled reconstruction of an approximately 51.1 kb fragment of a divergent gammaherpesvirus genome. These findings demonstrate the value of mNGS for wildlife disease investigation and genomic surveillance, while emphasizing the need for independent validation of metagenomic taxonomic assignments.

Introduction: Contagious ecthyma (CE) is a skin disease of goats, sheep and some other domesticated and wild ruminants worldwide, including Poland. The infection is caused by the orf virus (ORFV) of the Parapoxvirus genus. It is characterised by the appearance of skin lesions in the form of papules and pustules, most often in the area of the mouth and nostrils, hooves and genitals. The disease causes economic losses, especially in countries with high sheep and goat production. In Europe, the threat posed by this disease is rather underestimated, but following the re-emergence of foot-and-mouth disease (FMD) in the region in 2025, there is increased vigilance and a need to have differential diagnostic methods proven and ready. Material and Methods: DNA was extracted from lesions on mouth and hooves of sheep. The animals were on a farm located in southwestern Poland on which FMD was ruled out. A PCR was performed using two pairs of specific primers for detecting vIL10 and GIF gene fragments which were then sequenced. Results: Sequencing confirmed ORFV infection in all tested sheep samples. The sequences obtained for Polish viruses were also highly homologous to other parapoxviruses, indicating that the method used may be applicable for broad diagnosis of parapoxvirus infections not only in ruminants. Conclusion: This is the first molecular characterisation of ORFV in sheep in Poland. It signals a potential herd biosecurity problem in view of the neglected but re-emerging nature of CE. The marked genetic divergence between Polish field ORFV isolates and currently available vaccine strains may influence CE vaccine efficacy in Poland.

Introduction: This study focused on the seasonal activity and species diversity of Culicoides biting midges collected from 11 locations along the western border of Poland and major livestock transit routes, and included screening for bluetongue virus (BTV) RNA. Material and Methods: The sampling was conducted between September and November 2024. Collected biting midges were counted and identified to the species level. The gonotrophic forms of the females were also determined. Pools of insects were tested for the presence of BTV genetic material using a reverse-transcription quantitative real-time PCR. Results: A total of 13,022 individuals were identified. The results revealed spatial and temporal variation in midge abundance, likely influenced by local environmental conditions. A sharp decline in activity was observed after week 44, coinciding with decreasing ambient temperatures The widespread presence of Culicoides obsoletus / scoticus complex, recognised vectors of BTV, was confirmed along with high abundance of C. punctatus , a species considered a potential vector. All gonotrophic forms were identified, and 57.3% of females had taken a blood meal, indicating active reproduction and frequent host-animal contact throughout the sampling period. Pools of blood-fed, parous and gravid females were tested for BTV RNA, but all samples returned negative results. Conclusion: Although no evidence of active BTV circulation was found, the presence of competent vectors and favourable autumn conditions highlights the potential risk of transmission. These findings underscore the need for continued entomological and virological surveillance to support early detection and control of BTV.

Introduction: The circulation of influenza D virus (IDV) has been confirmed in Europe, North America, Asia and Africa through seroprevalence and molecular studies, as well as by virus isolation. Its broad host range raises concerns about zoonotic potential, with cattle recognised as the natural reservoir. This study finds the seroprevalence of IDV in cattle, associates animal-level variables such as age, sex and origin and assesses the frequency of IDV exposure in small ruminants and horses in Poland. Material and Methods: A total of 1,029 serum samples were analysed, comprising 755 from cattle, 224 from small ruminants and 50 from horses. To assess the serological response, haemagglutination inhibition tests were performed, and samples classified as positive were subsequently tested with a virus neutralisation test. Results: The findings suggest possible circulation of IDV among cattle in Poland and give an estimated seroprevalence of 45.2%. Seroprevalence was related to age, with older cattle being more likely to test IDV seropositive. Regional differences were also observed, with the highest seroprevalence found in the Wielkopolskie voivodeship, an area known for its intensive cattle farming and one of the largest bovine populations in Poland, exceeding one million animals. No confirmation of IDV occurrence was obtained in any of the 274 sheep, goats, or horses. Conclusion: To the best of our knowledge, this is the first evidence of IDV circulation in the country, highlighting the need for further research to better understand the virus’ transmission pathways.

Introduction: Trichinella spp. is an important zoonotic nematode parasite which infects a variety of hosts, not only including omnivorous and carnivorous animals but also herbivores. The environment and wildlife play a crucial role in nematode circulation in Poland. Trichinella spp. are present in prey animals, and the growth in the wolf population makes them potentially one of the major reservoirs, spreaders and/or indicators of Trichinella presence in their prey. The main aims of the study were to demonstrate the prevalence of Trichinella spp. in wolves, identify the predilection sites, and evaluate the species diversity and possible risk factors. Material and Methods: Forelimb, diaphragm and tongue muscle samples from 96 wolves from all over the country were examined by microscopy and molecular identification of parasitic isolates from them was made by multiplex PCR. Results: A total of 43 wolves (44%) were infected with Trichinella spp. For the first time, T. spiralis was detected in these animals, being noted in almost half of the cases. Trichinella spiralis infections were clustered in the north-west of the country. Conclusion: The high Trichinella prevalence in the apex predator suggests the wolf’s growing importance in the circulation and transmission of this food-borne parasite. This also indicates the importance of the disposal of carcasses to prevent the risks of animal and human exposure to this dangerous pathogen and the spread of Trichinella in a sylvatic environment.

Contrary to extensively studied porcine alphaherpesvirus (SuHV-1/PRV), betaherpesvirus (SuHV-2/PCMV) and Gammaherpesvirinae (SuHV-3/PLHV-1, SuHV-4/PLHV-2, SuHV-5/PLHV-3) infections remain unexplored in the swine population in Poland. The aim of this study was to characterise the prevalence of infections and local strains from each major herpesvirus subfamily on a large-scale weaner farm located in Poland. Nasal swabs collected from pigs at 6, 8 and 10 weeks of age were tested for the presence of herpesvirus infections using nested PCR specific to the pan-herpesvirus DNA polymerase (DPol) gene. The amplicons obtained from the positive samples were sequenced using the Sanger method. In total, 60% of the pigs were positive for herpesviruses, including 35.6% for porcine cytomegalovirus (SuHV-2/PCMV) and 24.4% for porcine lymphotropic herpesvirus type 1 (SuHV-3/PLHV-1). The infection rate was lowest in 6-week-old pigs—20% (6.7%—PCMV, 13.3%—PLHV-1) in comparison to 8-week-old—80% (53.3%—PCMV, 26.7% PLHV-1)—and 10-week-old pigs—80% (46.7%—PCMV, 33.3%—PLHV-1). No correlation between PCMV and PLHV-1 infections and coinfections with IAV, PRV1 or PRRSV was observed. Sequence analysis of both PLHV-1 and PCMV showed high genetic uniformity. Additionally, PLHV-1 isolates showed a close relationship to strains isolated from wild boar in Poland and pigs in Germany in recent years. In summary, our study confirmed the presence of both PLHV-1 and PCMV infections occurring early in piglet development, probably after passive immunity cessation.

Since the emergence of serotype BTV-3, another bluetongue virus, in fall 2023, this variant has been causing great losses in livestock farming in Europe. The virus spreads faster than the epidemic BTV-8, which appeared on the continent nine years earlier. This study describes the first case of BTV-3 in Poland detected in a European bison (Bison bonasus) in Poland’s Wolin National Park, approximately 15 km from the German–Polish border. The animal suffered from a severe and fatal hemorrhagic disease. The symptoms included respiratory problems, bloody diarrhea, and rapidly progressive cachexia. In addition to the virus’s confirmation as BTV-3 and the presence of the infecting agent in the blood and spleen of the animal, the virus was also detected in one pool of blood-fed Culicoides punctatus caught near the bison enclosure two weeks after the death of the bison. This is the first detection of BTV-3 in C. punctatus, which suggests vector competency for this serotype. Phylogenetic analysis based on segment 2 of the virus revealed the homology of the Polish isolate to the BTV-3 strains circulating in the Netherlands, Germany, and Portugal, and slightly lower similarity to the BTV-3 strains detected in sheep in Sardinia (Italy) in 2018 and in Tunisia in November 2016. A retrospective serosurvey of the exposure to BTV in thirteen other European bison populations distributed over the country indicated that the observed case at the Wolin National Park was the first BTV-3 to be detected in Poland.

The emergence of an another bluetongue virus serotype BTV-3 has been causing great losses in animal farming in Europe since fall 2023. The virus spreads faster than the epidemic BTV-8, which appeared on the continent nine years earlier. The study describes first case of BTV-3 in Poland detected in European bison (Bison bonasus), just approx. 15 km from the German-Polish border. The animal suffered from severe and fatal hemorrhagic disease. The symptoms included respiratory problems, bloody diarrhea and rapidly progressive cachexia. In addition to confirmation of BTV-3 infection in the blood and spleen of the animal, the virus was also detected in one of pool of blood-fed Culicoides punctatus caught near the enclosure two weeks after the death of European bison. This is the first evidence of BTV-3 detection in C. punctatus what suggests vector competency for this serotype. Phylogenetic analysis based on the segment 2 of the virus revealed homology of Polish isolate to the BTV-3 strains circulating in the Netherlands, Germany and Portugal, and slightly lower similarity the BTV-3 strains detected in sheep in Sardinia (Italy) in 2018 and in Tunisia in November 2016. Retrospective serosurvey of the exposure to BTV in thirteen other European bison populations widespread in the country indicated that the observed case at the Wolin National Park was the first BTV-3 to be detected in Poland.

Introduction: In winter 2021/2022, a wolf population in the primeval Białowieża Forest in Poland was struck by an outbreak of severe mange caused by mixed infestations of Sarcoptes and Demodex mites. We present an epidemiological analysis of this mange which caused significant morbidity and mortality. Material and Methods: Ten sites known for wolf activity were monitored by camera trapping. A diagnostic necropsy and testing of a young wolf was performed to determine the causes of death. Results: Five young wolves with severe alopecia of the entire body and some other individuals with minor to medium mange lesions were identified by the camera surveillance. The necropsy of the carcass revealed emaciation, dehydration and anaemia with starvation as the cause of death, likely attributable to severe infestation with Sarcoptes scabiei and Demodex sp. mites. Rabies and infections with Borreliella sp., Anaplasma sp., Ehrlichia sp., Francisella tularensis, Babesia sp. and tick-borne encephalitis virus were excluded by specific tests. Conclusions: The described analysis is the first documented co-infestation of this kind in wolves. The outbreak coincided with very mild winter conditions with a high average minimum temperature, which may have favoured mite survival outside the host, and light snowfall, which may have influenced the wolves’ ability to hunt. Other potential drivers of the outbreak could be the large proportion of wetland terrain, increasing number of wolves in the area and anthropogenic pressure on their habitats including the migration crisis at the Polish–Belarusian border and the increased presence of military and border forces, even despite the relief from the anthropogenic pressure from tourism due to the COVID-19 lockdown.