Asian Research Thesis Index

Abstract

Contagious bovine pleuropneumonia is a highly contagious disease of cattle caused by Mycoplasma mycoides subsp. mycoides. It is characterized by anorexia, fever, dyspnea, polypnea, cough, and nasal discharges. Gross lesions in the lung such as marbling, sequestra, thickening of interlobular septa, and consolidation are evident. Lesions are often unilateral with up to 10 liters of straw-colored fluid in thoracic cavity. Complement fixation test, competitive enzyme-linked immunosorbent assay and polymerase chain reactions are used for diagnosis purposes. In this study, blood samples of suspected large ruminants (cattle n=560, buffalo n=293) showing respiratory signs before slaughtering, were collected from abattoirs of three districts of Punjab namely Lahore, Kasur and Jhang. Lungs and lymph node samples of same animals were also collected after slaughter. On the basis of PCR results, 49 samples (8.75%) were detected as positive cases of contagious bovine pleuropneumonia, with maximum prevalence was observed in Jhang with 16 positive samples (10.06%). High prevalence of disease was seen in female cattle, cattle of more than seven years of age and in cross-bred cattle. On the basis of gene sequencing targeting 16S ribosomal RNA gene, 5 isolates of Mycoplasma mycoides subsp. mycoides were identified having more than 99% similarities with the strains isolated from China, Italy Australia, and Tanzania but least with that isolated from Portugal (<45%). On the basis of ELISA result, antibodies against contagious bovine pleuropneumonia were found in 48 samples, hence seroprevalence was 8.57% in cattle samples. No buffalo sample was detected positive either through PCR or ELISA. On necropsy, consolidation, marbling, sequestra, and fibrosis were observed in lung samples. on histopathological examinations thickening of interlobular septa, inflammatory cells infiltration, pulmonary congestion, alveolitis, bronchiolitis, and suppurative bronchopneumonia were observed in lungs, while mild pathological changes were seen in liver and kidney samples and in lymph node, hyperplasia of immune cells was investigated. A high significant difference (P<0.05) was observed regarding the values of interferon-gamma and interleukin-10 between infected and non-infected animals. This study confirms the presence of contagious bovine pleuropneumonia in the country which can be a threat to livestock export market and warrants the implementation of control measures to mitigate the economic losses associated with the disease.

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