Preventive measures in small ruminant farms suspected of paratuberculosis

Paratuberculosis or Johne's disease caused by Mycobacterium avium subspecies paratuberculosis chronic disease, incurable, difficult to diagnose in ruminants. Economic losses, direct and indirect, associated with it and possible links to Crohn's disease in humans, justifying more and more exhaustive study of this disease, and the establishment of preventive measures. An epidemiological survey was conducted on 13 sheep farms or effectives in the region of Serra da Estrela, in Portugal, with clinical suspicion of paratuberculosis, with the objective to to identified flock’s carriers of disease cases and, subsequently, characterize and identify the main risk factors and implement prophylactic measures, as part of an eradication plane that allows it’s control. Therefore, in this work were tested several diagnosis’ methods, that included serological methods, histopatological diagnosis’ methods, immunohistochemical`s methods, direct PCR and bacteriological culture. The results were presented in details and revealed positive animals in the different diagnostic techniques. The serological methods revealed, by Enzime Linked Immunosorbent Assay (ELISA), 235 positive samples (9.1%) 45 doubtful (1.7%), in 2589 samples and by Agar Gel Immunodiffusion (AGID) 30 positive samples. In histopathological exam, considering the presence of at least one of the microscopic lesions characteristic of the disease, we classified 26 (60,5%) animals as compatible with Paratuberculosis. In Ziehl-Neelsen method was observed alcohol-acid-resistant bacteria in 20 animals (46,5%). In immunohistochemical method, also 20 animals (46,5%) revealed the presence of MAP. The PCR analysis of samples collected at necropsies, revealed 35 positive animals (81,4%). So, all the diagnostic tests applied, showed lower sensitivity than the PCR technique of tissues. The authors concluded that the incidence of the disease in this Portuguese region was high and regarding the preventive measures and given the specific characteristics of the farms of this particular region the authors proposed: the conduct of surveys to identify animals carrying the disease, attention to verify the origin of the animals to acquire surveillance of symptoms shown by animals, isolation of lambs, the use of previously pasteurized colostrums, prevent the use of manure on fertilization of pastures