Molecular Diagnosis of Mycobacterium bovis Infection

Tuberculosis due to Mycobacterium bovis infection presents a significant public and animal health burden, in particular in economically less developed countries. Distinguishing M. bovis from other mycobacteria, and distinguishing among M. bovis strains, are important for M. bovis control and eradication, and for optimizing treatment plans for patients. Conventional diagnostic methods, such as tuberculin skin tests and microscopic examination of blood smears, are rapid and inexpensive, but generally do not allow differentiation among mycobacteria or mycobacterial strains. A variety of methods have been developed that allow detailed genetic characterization of mycobacteria. These methods are useful for epidemiologic investigation of outbreaks, identifying potential means and patterns of transmission, identifying relationships among infections in various human and animal populations, and investigating the role of wildlife reservoirs in maintenance and spread of infection. These methods can also be used to identify risk factors for transmission, to assess the effectiveness of tuberculosis control and eradication programs, and to assess quality control in laboratory testing. Limitations of these methods include higher costs, and requirements for more specialized equipment, reagents, and expertise than are needed for conventional diagnostic methods. Identifying the most appropriate method or combination of methods to use can be difficult. Factors to consider in selecting a molecular diagnostic approach include the purpose of the investigation, and the structure and molecular characteristics of the M. bovis population under investigation. Use of inappropriate methods can yield misleading results and lead to significant waste of resources.