Analysis of virus infections in shipping fever pneumonia of cattle: emergence of respiratory coronaviruses

摘要

Shipping fever pneumonia (SFP) is an acute respiratory tract disease, and remains a serious problem in beef cattle recently transported to feed-lots. This form of pneumonia is characterized by fever, dyspnea and exudative inflammatory and necrotizing lung lesions (Hoerlein, 1980; Yates, 1982), and affected 64 percent of fatal cases in a study of feedlot cattle in Colorado (Jensen et al., 1976). A multifactorial etiological concept for SFP is widely accepted in scientific circles, which implies thatcrowding and other stressful conditions favor virus spread and infections of respiratory tracts that, in some instances, become further complicated with Pasteurella and other bacterial infections, often leading to fatal pneumonia (Hoerlein, 1980; Yates,1982). Losses from SFP continue to occur in spite of widespread use of modern management and vaccination programs derived from decades of intensive research on physiological factors, infectious agents and pathogenesis of respiratory tract diseases, defense mechanisms and immune responses of cattle, modern vaccines, metaphylactic and therapeutic antibiotic treatments, and improved diagnostic tools.