There are fears of a bovine tuberculosis outbreak after the disease spread from pets to humans.
Public Health England now report there are two people in England who have developed tuberculosis after contact with a domestic cat infected with Mycobacterium bovis, also known as bovine TB. M. bovis is the bacterium that causes tuberculosis (TB) in cattle and bovine TB in other species.
Nine cases of ‘M. bovis’ infection in domestic cats in Berkshire and Hampshire were investigated and 39 people identified as having had contact with the infected cats as a precautionary measure.
Following further investigations, a total of 2 cases of active TB and 2 cases of latent TB were identified. Latent TB means they had been exposed to TB at some point but they did not have active disease.
Both cases of active TB disease have confirmed infection with ‘M. bovis’ and are responding to treatment.
There have been no further cases of TB in cats reported in Berkshire or Hampshire since March 2013. PHE has assessed the risk of transmission of ‘M. bovis’ from cats to humans as being very low.
Dr Dilys Morgan, head of gastrointestinal, emerging and zoonotic diseases department at PHE, said:
It’s important to remember that this was a very unusual cluster of TB in domestic cats. ‘M. bovis’ is still uncommon in cats – it mainly affects livestock animals. These are the first documented cases of cat-to-human transmission, and so although PHE has assessed the risk of people catching this infection from infected cats as being very low, we are recommending that household and close contacts of cats with confirmed ‘M. bovis’ infection should be assessed and receive public health advice.
Molecular analysis at AHVLA showed that ‘M. bovis’ isolated from the infected cats and the human cases with active TB infection were indistinguishable, which indicates transmission of the bacterium from an infected cat.
In the other cases of latent TB infection, it is not possible to confirm whether these were caused by ‘M. bovis’ or the source of their exposure.
Transmission of ‘M. bovis’ from infected animals to humans can occur by inhaling or ingesting bacteria shed by the animal or through contamination of unprotected cuts in the skin while handling infected animals or their carcasses.
Those working closely with livestock, or regularly drinking unpasteurised (raw) milk have a greater risk of exposure.