ASSOCIATED FACTORS, PATHOLOGY AND VACCINATION STRATEGIES OF CAPRINE PNEUMONIA IN NIGERIA

Abstract

Pneumonia remains a major limitation to goat production in Africa because of the ineffectiveness of chemotherapy and vaccination currently used for its control. In Nigeria, there is dearth of information on bacteria-viruses interaction involved in caprine pneumonia. This study is designed to therefore evaluate the associated factors, aetiology, pathology, and markers of infection towards improving therapeutic and vaccination strategies for caprine pneumonia in Nigeria. Goats (n=700) from Northern and Southern Nigeria in three different management systems [extensive (n=332), intensive (n=85), semi intensive (n=283)] were studied across seasons [dry (n=241), wet (n=459)] for body score, clinical signs. At postmortem, pneumonia and Consolidation Scores (CS), histopathology and bacteria presence were examined. Blood and Broncho-Alveolar Lavage fluid (BALf) were collected from 300 goats for haematology and cytology, respectively using standard techniques. Samples from 192 BALf were also assayed for antioxidants [Reduced Glutathione (GSH), Glutathione Peroxidase (GPx), Glutathione Transferase (GST), Superoxide Dismutase (SOD)] activities and prooxidants [Malondialdehyde content, Hydrogen peroxide (H2O2) generation, Myeloperoxidase] using spectrophotometric methods. Tissues from the lungs (n=150) were further examined for antigens to Para-Influenza-3 (PI-3), Respiratory Syncytial (RS) and Peste des Petits Ruminants (PPR) viruses, as well as Pasturella multocida (Pm) and Mannheimia haemolytica (Mh) immunohistochemically using the streptavidin-peroxidase method. Sixteen healthy goats were further divided randomly into four groups: intranasally vaccinated (PPR+Mh, PPR+Pm, PPR) and unvaccinated, before exposure to field PPR infection. The goats were examined clinically daily for three months; blood obtained weekly were analysed while weak animals were euthanized and lungs examined for pneumonia and associated histopathology. Data were analysed using descriptive statistics, chi-square test and ANOVA at α0.05. The prevalence of caprine pneumonia was 60.0%, with a mean CS of 8.1+0.5. Season (OR=0.5; CI=0.4-0.7), and body score (OR=0.7; CI=0.5-0.9) were identified as associated factors of pneumonia. The types of pneumonia were bronchopneumonia (70.0%), bronchointerstitial (15.0%), interstitial (13.0%) and granulomatous (2.0%) pneumonias. The most frequently isolated bacteria were Mh (87.0%) and Pm (44.0%). There were leukocytosis and neutrophilia in all the pneumonic goats, lymphocytosis and neutrophilia in bronchopneumonia, and leucopaenia in interstitial pneumonia. Neutrophil, macrophage, eosinophil and mast cell counts increased in the BALf of pneumonic goats. Also, the Malondialdehyde contents, H2O2 and Myeloperoxidase levels increased while GSH level and SOD activity decreased. Distributions of the antigens were; PPR (15.0%), PI-3 (4.0%), RSV (0.0%), Pm (19.0%), Mh (4.0%), PPR and Mh (13.0%), PPR and Pm (8.0%), PI-3 and Pm (12.0%), PI-3 and Mh (7.0%), RSV and Mh (6.0%) and RSV and Pm (3.0%). There was pyrexia, oculo-nasal discharge, diarrhoea, anaemia and leucopaenia in the unvaccinated goats, while neutrophilia and leucocytosis were in PPR+Pm and PPR vaccinated goats. There was severe diffuse bronchointerstitial giant cell pneumonia in the unvaccinated goats, fibrinous bronchopneumonia in PPR vaccinated goats and no pneumonia in the PPR+Mh vaccinated goats. Antioxidant therapy and intranasal vaccination with multivalent vaccine incorporating Peste des Petits Ruminants virus, Mannheimia haemolytica and other identified pathogens: Pasturella multocida, Para-Influenza-3 virus and Respiratory syncytial virus are recommended as an effective approach to the control of caprine pneumonia in Nigeria. Keywords: Goats, Pneumonia, Peste des Petits Ruminants virus, Mannheimia haemolytica, Intranasal vaccination. Word count: 498