Tuberculosis outbreak in intensive swine farming from southern Brazil

Abstract

Mycobacterium tuberculosis var. bovis is the etiologic agent of animal tuberculosis (aTB), a neglected zoonotic disease. Animal tuberculosis can affect many species, including swine. aTB-consistent granulomas in these animals lead to carcass disposal, generating economic losses and posing risks to human health. In the present study, an aTB outbreak was identified at an intensive swine farming operation in Southern Brazil. Inspection during swine slaughter revealed aTB-suspected lesions, which were collected for diagnosis by histology, PCR, and bacterial isolation. The animals had no clinical signs of tuberculosis. Granulomatous lesions were identified in 0.73% (59/8,071) of the slaughtered swine, and were confirmed by histology. Nine samples were further examined by PCR and bacterial isolation, with 44.4% and 55.5% positive results, respectively. Data from abattoirs subjected to federal surveillance show an aTB prevalence in Brazil of <0.001%. The present data thus indicate a swine aTB outbreak in intensive breeding. Swine infection can be related to exposure to infected animals or to contaminated food or environment. Biosecurity measures must be taken to avoid aTB transmission. Although certified swine breeding farms adopt such measures, this report indicates that constant monitoring is crucial, and greater control in swine breeding and finishing units is required to prevent outbreaks and spread of tuberculosis.