[Swine-spread severe influenza-associated pneumonia: A case report and literature review].

We report and analyze the clinical data of the first case of severe pneumonia caused by influenza B virus from swine. The patient, a 62 year-old male domestic pig breeder, was admitted to hospital because of fever and muscle pain for 5 days, and anhelation for 3 days. One week before the onset of disease, the patient kept close contact with pigs. CT scan of the chest showed diffuse infiltration in both lungs. Influenza B virus antigen detection (colloidal gold method) was repeatedly positive. These all confirmed influenza B virus infection. Poor appetite, weight loss, cough, poor spirit of pigs, positive influenza B virus antigen test occurred in the pig, while the patient had no history of exposure to influenza B-infected patients. It was likely that influenza B virus was transmitted from domestic pigs to the patient by droplets or close contact. Influenza B virus epidemics always occur every five or six years a time, and patients and carriers are the main source of infection. After searching the Pubmed, Web of science, Elsevier, Wanfang, and CNKI databases, it was found that although there were many studies on influenza B virus infecting seals, ferret, domestic pigs, guinea pigs, and other animals, there was no case report for animal-to-human infection. It is the first case report of type B influenza virus transmission from domestic pigs to people in the world, which provides a new direction for the research and prevention of influenza B virus.