Inferring Mycobacterium bovis transmission between cattle and badgers using isolates from the Randomised Badger...

Area of Science:

• Veterinary Epidemiology
• Genomic Epidemiology
• Disease Ecology

Background:

• Mycobacterium bovis (M. bovis) causes bovine tuberculosis, a major economic and animal health concern globally.
• Understanding M. bovis transmission dynamics between cattle and wildlife, such as badgers, is crucial for disease control.

Purpose of the Study:

• To investigate the transmission routes and rates of M. bovis between badgers and cattle using genomic and epidemiological data.
• To identify the primary drivers of M. bovis transmission clusters in cattle populations.

Main Methods:

• Whole genome sequencing of 1,442 M. bovis isolates from badgers and cattle.
• Integration of genomic data with location and cattle movement records.
• Phylogenetic analysis to infer transmission clusters and rates.

Main Results:

• Most M. bovis transmission clusters were established recently, often linked to cattle movement.
• Transmission from badger to cattle was estimated to be twice as high as from cattle to badger.
• Within-species transmission in cattle significantly exceeded cross-species transmission.
• Cattle movement was associated with long-distance transmission events and superspreading.

Conclusions:

• Bovine tuberculosis clusters in Southwest England were likely seeded by long-distance cattle movements.
• Within-species transmission within cattle herds is the main driver of cluster maintenance.
• While spill-over occurs, wildlife reservoirs are less critical for current cluster dynamics than cattle movements.