Human-to-Bovine M. Tuberculosis Transmission A Reverse Zoonosis
Human-to-Bovine M. Tuberculosis Transmission
A Reverse Zoonosis
L. Gunaseelan, V. Bhnurekha, G. Pawar, R. Nassiri
Department of Veterinary Public Health and Epidemiology, Madras
University, and Tamil Nadu Veterinary and Animal Sciences University,
Institute of International Health, Michigan State University
East Lansing, Michigan, USA
Prof. Reza Nassiri
• Zoonosis constitute 60-65% of all known
infectious diseases, 75% of the infections
considered “emerging” are zoonosis.
• Historically the link between animal and human
tuberculosis has always been strong.
• Zoonotic Mycobacterium tuberculosis is both a public
and One Health threat.
• Transmission from animals to human (and vice
versa) in developing countries remains a
significant public health danger, most from
consumption of unpasteurized milk,
consumption of daily products made from
• Detection of mycobacterium through
molecular epidemiology techniques is an
important step in disease characterization.
• M. tuberculosis, M. bovis and M. africanum
together with Mycobacterium microti
(associated with infection of rodents) from a
very closely related phylogenetic group may
be referred to collectively as the M.
tuberculosis complex (MTBC).
Central Hypothesis of This Study
• Reverse zoonotic tuberculosis should be
investigated through the means of molecular
epidemiology to assess the risk and to better
understand the dynamics of the disease
transmission with respect to identification of
types and sub-types.
• Our hypothesis would allow subsequent
surveillance, control, preventive, and
• To make an assessment of zoonotic
tuberculosis transmission (Human-to-animal;
reverse zoonosis) in Chennai, India.
• Application of molecular epidemiology as a tool in
zoonotic TB surveillance, screening and detection in
both human and animal populations.
• A total of 181 bovine milk samples and 113
pre-scapular lymph node biopsy samples were
• Teaching and Research hospital (Madras
Veterinary College, Chennai)
• University research farm
• Two slaughter houses in Chennai districts
• Acid fast staining
• Florescent staining
• Molecular confirmation by MTBC genus PCR
• Targeting IS6110 region
• Molecular confirmation by multiplex PCR to
differentiate M. tuberculosis and M. bovis
• 3 primers: CSB1 Common FP, CSB2 M. bovis, CSB3
• Phylogenetic tree analysis using MEGA5
• Comparing all diagnostic tests for TB
detection, in-house PCR targeting the IS6110
and multiplex PCR provide much higher
• Phylogenetic tree analysis and gene
sequences of bovine isolate 1,2 and 3
matched human sputum isolates from Kerala,
India – Madhavilatha et al, 2012, J. Bacteriol.
• Transmission of Mycobacterium tuberculosis from
Human to Cattle – Natjaz Ocepek et al, J. of Clinical
Microbiol, July 2005
• Described the first transmission of Mycobacterium
tuberculosis from human to cattle using molecular typing
of isolates involved in the transmission.
• IS6110-based restriction fragment length polymorphism
analysis showed that the isolates from the cattle and a
farm worker who suffered from pulmonary tuberculosis 1
year prior to the case were the same strain.
One Health Implications
• Stop the cycle of transmission between
humans and cattle, and vice versa.
• Train stakeholders for best practices in disease
screening, detection, and cross-species
transmission interventional strategies.
• Develop a comprehensive communication
strategy to increase reverse zoonotic TB
awareness and to galvanize political will.
• We have shown the presence human M.
tuberculosis in animal milk and lymph
• Our study which identifies molecular types of
M. tuberculosis complex strains from cattle
milk, establishes a baseline for an effective
public health and One Health control
measures of tuberculosis in both humans and
animals with implications for policymaking.