Quantification And Localization Within The Bronchial Tree Of Lesions Induced By Mycoplasma Hyopneumoniae In Naturally Infected Pigs

Abstract

Mycoplasma hyopneumoniae (Mh) is the primary agent of porcine enzootic pneumonia. The predominant histological lesion is hyperplasia of the bronchus-associated lymphoid tissue (BALT). Livingston et al. (1972) classified these lesions into four stages. The aim of this study was to determinate the severity of the histological lesions, quantify and locate them within the bronchial tree. Materials and Methods: Thirty-five pigs were inspected at slaughter. Pneumonia patterns and the percentage of affected lung parenchyma were determined. The BALT of each bronchus and bronchiole was evaluated and immunohistochemical study against Mh was performed. Results: Eighty-three per cent of animals showed cranioventral bronchopneumonia with 12.9% having pneumonic lesions. The predominant histological lesion was stage II (72.4%). In bronchi, bronchioles and in terminal and respiratory bronchioles stage II also predominated (44, 55.2 and 65%, respectively). Mh was detected in the 65.5% of the animals. Conclusions: Changes in the localization of Mh within the bronchial tree during the course of infection have been reported. In this study we have determined the distribution of Mh-induced lesions within the different parts of the bronchial tree. Further studies are desirable to research the immune response in the different levels of the bronchial tree.