Some people consider tuberculosis to be a disease of historical interest, but TB is alive and well, and spreading. TB is caused by Mycobacterium tuberculosis, a microorganism that can cause severe lung disease. TB rates are climbing rapidly in some countries and the emergence of highly drug resistant strains is a major concern. Anytime infectious diseases become more common in people in the general population, there is the potential for exposure of household pets. Recently, transmission of TB from humans to different animal species, including a dog, was reported. This follows earlier sporadic reports of TB in dogs. Finding TB in pets, albeit a small number, raises concerns about the potential role of pets in transmission of TB back to people.
Diagnosis of TB in pets is not particularly surprising, since it has been clearly shown by a few other infectious diseases that disease trends in people can sometime be reflected in their pets. It’s hard to say if this is an under-recognized problem, an emerging problem or a very rare event that gets a lot of publicity. Really, the only way to tell will be to see what happens over time. Currently, TB is very rare in pets so it is important to keep possible risks and concerns in perspective. There is no reason for pet owners with TB to give up their pets. People with active TB should consider their pets as part of the family, and interact with them as they have been instructed to with people (i.e. if they are supposed to avoid close contact with people they should do the same with their pets).
There is currently no indication that infected pets can transmit TB back to people, and the risks are probably very low. TB is most easily spread through coughing, and pets with TB rarely develop respiratory disease with coughing. That, combined with the rarity of TB in pets, means that the risk of acquiring TB is much, much higher from other people than from pets.
This is just one more example of the “one medicine” concept, whereby we need to break down the barriers between ‘animal diseases’ and ‘human diseases’ (because the bugs are clearly doing so).