Retrospective serological and virological survey of influenza D virus among cattle in Sweden

Sammanfattning: Respiratory diseases in cattle can cause economic losses due to the decreased dairy and meat production. Virus is the main reason for these diseases. Symptoms can be fever, cough and nasal discharge.     Influenza are a group of viruses belonged in the Ortomyxoviridae family. The big influenza groups are influenza A, B and C. The viruses can cause respiratory signs, and mammals can be affected. Recently a new influenza virus was found in the United States. The influenza virus was found in swine, but the natural host was later considered to be cattle. The virus was named influenza D. Different studies worldwide have confirmed the virus in a variety of regions. Antibodies have also been reported.     In this study, virologic and serologic methods were used to detect if influenza D circulates among cattle in Sweden. The serologic method performed was indirect ELISA. Serum and milk samples were investigated in the ELISA method. For the virologic detection a real-time RT-PCR was made, with a variety of study material.     Antibodies against influenza D were found in both serum and milk samples. No virus was found in the real-time RT-PCR. In Sweden the animal keeping is different compared to several other nations. For instance, the conditions of health and hygiene are better in Sweden, this may be an important cause of a system more resistant against spreading of infections. Influenza D could be more common in Sweden, but in that case further researches are needed to determine the prevalence.