Mycobacterium bovis: Milk Safety & TB Control

Mycobacterium bovis

Before pasteurization was universal, milk was a major route of tuberculosis. Mycobacterium bovis — bovine TB — moved from infected udders into milk bottles and from there into children’s bones and lymph nodes. Pasteurization ended that era where it’s applied.

Taxonomy & characteristics

• Mycobacterium bovis; acid-fast bacillus in the M. tuberculosis complex. Very hardy in the environment; survives in dairy products for extended periods.
• Killed by proper pasteurization — one of the original public-health justifications for it.
• Illness: extrapulmonary TB — cervical lymphadenitis (scrofula), bone and joint TB; clinically similar to human TB, same long treatment.

Sources & high-risk foods

• Reservoir: infected cattle (also badgers, deer, other wildlife in endemic areas).
• High-risk: unpasteurized milk and dairy products — fresh cheeses especially; undercooked meat from infected animals (lower risk).

Control measures

• Pasteurization of all milk for direct consumption — non-negotiable where bovine TB exists.
• Herd testing and culling (the tuberculin test-and-slaughter programs); wildlife reservoirs complicate eradication.
• Meat inspection: detection of TB lesions at slaughter.

Eradication progress

Bovine TB control is one of public health’s long success stories: test-and-slaughter programs plus milk pasteurization drove M. bovis disease in humans to near zero in countries that implemented both. Where it persists — parts of Africa, Asia, and Latin America — unpasteurized milk remains the main exposure route, and human cases still occur. Wildlife reservoirs (badgers in the UK and Ireland, deer elsewhere) complicate final eradication and keep surveillance programs busy. For the food professional, the lesson is institutional: pasteurization plus herd health programs solved a major zoonosis in a century, and dismantling either control would invite it back.

Wildlife reservoirs (badgers in the UK and Ireland, deer elsewhere, possums in New Zealand) complicate final eradication — from controversial culling to promising-but-slow vaccination — and keep surveillance programs busy. For the dairy and beef industries, the ongoing cost of testing and movement controls is the price of keeping a conquered disease conquered.

Sources: WHO; OIE; CDC.