Abstract
BACKGROUND: Respiratory diseases are globally a major challenge in today's pig production. Despite the efforts to manage the disease, the number of pigs affected is still increasing, indicating gaps in the current knowledge. In 2016, a novel pneumovirus, swine orthopneumovirus, was detected in the USA. Since then, the virus has been detected in a few European countries and in South Korea. However, the wider distribution of the virus is still greatly unknown, as well as its clinical relevance. CASE PRESENTATION: This report describes the first detection of swine orthopneumovirus in a Swedish pig herd. The virus was detected as the result of an investigation conducted between September 2023 to June 2024, where all clinical samples (n = 682) sent to the Swedish Veterinary Agency for diagnostic purposes from 112 Swedish pig farms exhibiting clinical signs of respiratory disease were screened for the presence of swine orthopneumovirus. The virus was detected in one piglet producing farm that had a respiratory disease outbreak in autumn 2023, which presented with cough and nasal discharge. In November 2023, 11 nasal swabs were collected, of which 9 were PCR-positive for swine orthopneumovirus. In addition, each sample was also PCR-positive for Mesomycoplasma hyorhinis and Pasteurella multocida, and 2 samples were PCR-positive for Actinobacillus pleuropneumoniae, indicating a polymicrobial respiratory infection. CONCLUSIONS: This report emphasises the importance of ongoing efforts to identify emerging pathogens and determine their clinical significance. Therefore, further research is needed to assess the distribution and potential clinical relevance of swine orthopneumovirus.