Molecular identification of Mycobacterium tuberculosis in cattle

Area of Science:

• Veterinary Microbiology
• Zoonotic Diseases
• Molecular Epidemiology

Background:

• Bovine tuberculosis (bTB) remains a significant re-emerging issue in endemic areas.
• Inadequate human and animal health surveillance systems hinder effective diagnosis and control.
• Shared habitats between humans and cattle in rural settings facilitate disease transmission.

Purpose of the Study:

• To investigate the prevalence and genetic characteristics of Mycobacterium tuberculosis complex (MTBC) in cattle.
• To differentiate between Mycobacterium tuberculosis and Mycobacterium bovis in bovine samples.
• To understand the implications of M. tuberculosis infection in cattle for public health.

Main Methods:

• Collection and culture of 148 cattle samples over 3 years.
• Identification of MTBC isolates using IS6110 PCR.
• Differentiation of M. tuberculosis and M. bovis using 12.7kb fragment multiplex PCR.
• Spoligotyping of IS6110 PCR positive isolates.

Main Results:

• 67 isolates were obtained, with 51 identified as MTBC.
• 43 isolates were M. tuberculosis and 8 were M. bovis.
• Spoligotyping revealed 28 M. tuberculosis isolates belonging to the MANU1 strain.
• M. tuberculosis was found to be more prevalent than M. bovis in cattle, contrary to previous assumptions.

Conclusions:

• This study demonstrates a higher prevalence of M. tuberculosis than M. bovis in cattle.
• Molecular methods confirmed M. tuberculosis can cause lesions in cattle, challenging prior beliefs.
• The M. tuberculosis MANU1 strain in cattle may result from spillover from human or other hosts in TB-endemic areas.
• M. tuberculosis infection in cattle warrants consideration in countries with high human TB prevalence.