Immunohistochemical Evidence of Multiple Viral and Bacterial Associations in Caprine Pneumonia in Nigeria: Implications for Vaccines

Abstract

DOI : 10.26650/actavet.2019.409009 Caprine pneumonia is a major cause of economic loss and the conventional vaccines are not optimal in protecting goats. A better understanding of the associations of respiratory pathogens may help improve our knowledge for vaccination to effectively control caprine pneumonia. One hundred and fifty goats (140 pneumonic and 10 normal) were examined for various lung pathologies using standard gross and histologic techniques. Antigens of parainfluenza 3 virus (PI3V), respiratory syncytial virus (RSV) and peste des petits ruminants virus (PPRV) and bacterial antigens of Mannheimia haemolytica (M.haemolytica) and Pasteurella multocida (P. multocida) were demonstrated immunohistochemically in the lungs. The data of goats positive and negative for the viral and bacterial antigens were analysed using descriptive statistics. Viral antigens were detected in 113 (81%) of the pneumonic lungs (100 as single, 11 dual and 2 triple). Bacterial antigens were detected in 120 (86%), M. haemolytica in 47 (34%),  P. multocida in 59 (42%) and combined bacterial antigens in 14 (10%) of the pneumonic lungs. Multiple agents were detected in 108/140 positive cases; virus-bacterium association was observed in 106/108. PPRV antigens alone were observed in 15 cases. PPRV coexisted most frequently with M. haemolytica (n=20), P. multocida (n=13), PI3V with P. multocida (n=18), and RSV with M. haemolytica (n=9). The lesions corresponded to cranioventral (n=45), diffuse (n=75), and lobar consolidations (n=20) manifested as fibrinous bronchopneumonia (n=22), suppurative bronchopneumonia (n=20), bronchointerstitial pneumonia (n=61), interstitial pneumonia (n=25) and bronchiolitis (n=12). Thus, multiple infections are involved in pneumonia, hence we must consider combined vaccination strategies incorporating multiple antigens for adequate control of caprine pneumonia.