Mycobacterium microti Interferes with Bovine Tuberculosis Surveillance

Area of Science:

• Veterinary Microbiology
• Infectious Diseases
• Public Health

Background:

• Mycobacterium microti, part of the Mycobacterium tuberculosis complex, traditionally affects wild rodents.
• Recent reports show M. microti in wildlife and livestock, posing a risk to bovine tuberculosis (bTB) surveillance programs in France.
• The increasing prevalence of M. microti in cattle necessitates a re-evaluation of current diagnostic strategies.

Purpose of the Study:

• To report the detection of M. microti in cattle herds in France.
• To assess the diagnostic challenges posed by M. microti in bTB surveillance.
• To recommend improved diagnostic approaches for accurate bTB detection.

Main Methods:

• Detection of M. microti in four cattle from three distinct herds.
• Ante-mortem diagnosis using the single intradermal comparative cervical tuberculin (SICCT) skin test.
• Confirmation of infection via molecular methods, including specific real-time PCR and spoligotyping.

Main Results:

• Positive SICCT skin test results in all infected cattle.
• Confirmation of M. microti infection through molecular testing.
• Identification of M. microti in cattle across different regions, indicating a potential spread.

Conclusions:

• M. microti poses a significant risk of interference with bTB diagnosis in France.
• Current diagnostic tests may not reliably distinguish M. microti from M. bovis or M. caprae.
• Implementing highly specific tests like interferon gamma (IFN-γ) assays or specific tuberculins, alongside molecular tools, is essential for accurate bTB diagnosis and surveillance.