Can Tuberculosis Be Contracted from Family Pets?

All members of the tuberculosis (TB) complex pose potential zoonotic risks.¹ Until recently, there were few published reports of humans infected by cats. In a historic case, a 3-year-old boy died from generalized infection after being bitten on the arm by a cat in the advanced clinical stages of Mycobacterium bovis TB.² In another case, a man in Australia with a colony of 5 cats and 2 possums—all of which had clinically confirmed M bovis infection—became Mantoux-test positive, although he was never clinically ill.³

More recently, a cluster of 9 cats in Great Britain was reported to have M bovis infections.⁴ Anecdotally, the author is aware of a household of 3 dogs with M bovis infections and a young son with subclinical TB.

Although these cases are rare, the TB risk should not be understated, and humans exposed to M bovis-infected cats—especially those with open, exudative lesions—should be assessed by their physicians and local health authorities.

• Potential sources of infection include domestic animals, wildlife (eg, rabbits, rodents), and soil.
• Cats can also develop TB from Mycobacterium microti infection (from voles, mice).
  • M microti is far less zoonotic than is M bovis, and no cat-to-human spread has been reported.
• Mycobacterium tuberculosis and M bovis can both be anthroponosic (ie, reverse zoonotic), and there have been a small number of unpublished cases in which humans have infected cats with M bovis.