Author : Nguyen Tat Toan

Summary : A study on Mycoplasma hyopneumoniae infection from fifteen selected pig farms in Luzon was conducted. Forty-six lung tissues and twelve nasal swabs suspected to be Mycoplasmal pneumonia of swine (MPS) were collected. Using clinico-pathological methods, namely: clinical signs, gross pathology, histopathology, bacterial isolation and Polymerase Chain Reaction (PCR), these suspected MPS field cases were diagnosed and confirmed. Also, the sensitivity, specificity, accuracy, positive and negative predictive values of each diagnostic method was determined. Clinical signs observed were coughing, labored breathing, pyrexia, unthrifty appearance, anorexia, and prolonged course. Gross lesions were confined to the lung and were clearly demarcated from the normal lung. Two types of gross lesion were observed: acute characterized by bilateral fawn, edematous and pink; chronic characterized by plum-colored, atelectatic areas of the anteroventral, of apical, cardiac and diaphragmatic lobes. The enlargement of bronchial and mediastinal lymph nodes was also seen in the infected pigs. In histopathology, peribronchiolar and perivascular lymphoid hyperplasia and lymphoid nodule formation were found to be the most common characteristic lesions associated with Mycoplasma hyopneumoniae infection. Mycoplasma hyopneumoniae isolation from 46 lung samples gave 4.34 (2/46) percent positive results while the 12 nasal swabs were all negative. In PCR identification, 17 pigs out of 34 (50%) showed a positive reaction in the PCR using DNA extracted from lung tissue. Twelve nasal swab samples of PCR identification of Mycoplasma hyopneumoniae from suspected infected swine were negative.