Lesions Consistent with Tuberculous Spondylitis in Domestic and Wild Swine and Their Potential Use as a Model for Pott Disease in Humans

Abstract

During a routine abattoir inspection of pig carcasses and control activities of hunted wildlife in 2013, 118 large white pigs Sus scrofa domesticus, 474 Nebrodi black pigs and 135 wild boars Sus scrofa scrofa were submitted to anatomopathological examination to evaluate the presence of tuberculosis-like lesions. Localized and generalized granulomatous lesions were detected with a prevalence of about 25% in large white pigs, 13% in Nebrodi black pigs and 8.15% in wild boars. Localized lesions involved mainly the submandibular lymph nodes, but when the disease was spread throughout the body, the inner organs and, also, in some cases, udders and/or bones were injured. The highest prevalence of generalized lesions (15/30) was observed in large white pigs, the only ones in which tuberculous granuloma affected also the spine. The bovine tuberculous spondylitis cases observed showed some similarities with Pott disease in humans regarding aspect and localization of lesions and age of the affected animals.Tissue samples of the positive animals were collected and submitted to bacteriological analysis, and the bone samples were also subjected to histological and immunohistochemistry analysis. M. bovis was isolated in all the analysed samples, and the granuloma encapsulation was found often incomplete indicating that the disease was in an active phase. The presence of lesions associated to tuberculous spondylitis in pigs suggests the possibility to use this animal species as model for the study of Pott disease in humans.