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Bovine tuberculosis in the Austrian alpine region

2019; Elsevier BV; Volume: 79; Linguagem: Inglês

10.1016/j.ijid.2018.11.161

1878-3511

Christoph Leth, Sandra Revilla‐Fernández, Maria Cristina Domingues Fink, Erwin Hofer, F. Schmoll,

Diagnosis and treatment of tuberculosis

Purpose: Mycobacterium caprae (M. caprae), a member of the Mycobacterium tuberculosis complex (MTBC), can infect a wide range of domestic animals, wild-life species and humans. M. caprae is the main causative agent for tuberculosis in cattle and red deer in the Alpine regions of Austria, Switzerland, Italy and Germany. It is not the major cause of human TB, which is caused by M. tuberculosis, but humans are susceptible and therefore, the zoonotic disease continues to have considerable public health implications. To estimate the prevalence of M. caprae in the Alps, 1 655 samples of free ranging red deer of different sexes and ages from Austria, Germany, Switzerland, and Italy were studied. Cattle samples from these regions were also tested. Methods & Materials: Tissues from organs with or without visible lesions were analysed by Real-Time PCR and bacteriological culture. To resolve the genetic evolution of M. caprae in Austria and the Alpine region in more detail, whole genome sequencing and SNP analyses were performed. SNP analysis revealed a more precise subtyping, suggesting transmission pathways. With matrixlysis, our new established detection method, we were able to detect small amounts of mycobacteria in tissue and a higher percentage of positive samples with non-visible lesions than shown for bacterial culture, the gold standard in M. tuberculosis complex diagnostic. Results: It was shown, that free ranging red deer is a maintenance host in hot-spot areas which are mainly located in Austria and Germany. Regions with prevalences up to 23% of infected red deer were defined. Interestingly, more than 2% of the positively detected animals showed no visible lesions but were positive by bacterial culture. Positive red deer isolates were subtyped by a RD4-based PCR allowing the genetic differentiation of M. caprae isolates into three subtypes termed "Allgäu", "Karwendel" and "Lechtal", according to their geographical origin. Conclusion: The different RD4-subtypes are found spatially distributed and occur in cattle as well as in red deer, suggesting transmission between the two species. Since subtypes are genetically stable in both host species, it is hypothesized that the genetic variations might have developed in the past due to "within-host" replication.