Changes

====Pathogenesis====

====Pathogenesis====

*More serious than [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]

*More serious than [[Bovine Parainfluenza - 3 (PI-3)|PI-3]]

*Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]

*Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]

*Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree

*Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree

*Syncytia form -> shed into bronchioles

*Syncytia form -> shed into bronchioles

*Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle

*Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle

====Epidemiology====

====Epidemiology====

**Subclinical reinfections are important in spreading disease

**Subclinical reinfections are important in spreading disease