Two people from England have developed tuberculosis after contact with an infected domestic cat - Public Health England, (Phe) and the Animal Health and Veterinary Laboratories Agency, (Ahvla), have announced.
It is the first time cat-to-human transmission of the disease, Mycobacterium bovis (M.bovis), normally found in cattle, has been reported in this country.
The two victims from Berkshire and Hampshire were responding to treatment, Phe said.
It is believed they could have caught the disease through either inhaling bacteria from the animal or through contamination via unprotected cuts in the skin while handling the infected animals.
Two other people were identified as having latent TB – meaning they have been exposed to the disease - but it had not developed.
Nine cases of 'M. bovis' infection in domestic cats in Berkshire and Hampshire were investigated by Ahvla and Phe in 2013.
Phe offered TB screening to 39 people in total as a precautionary measure.
There have been no further cases of TB in cats reported in Berkshire or Hampshire since March 2013.
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."
Professor Noel Smith, Head of the Bovine TB Genotyping Group at Ahvla, said: "Testing of nearby herds revealed a small number of infected cattle with the same strain of 'M. bovis' as the cats. However, direct contact of the cats with these cattle was unlikely considering their roaming ranges. The most likely source of infection is infected wildlife, but cat-to-cat transmission cannot be ruled out.
"Cattle herds with confirmed cases of bovine TB in the area have all been placed under movement restrictions to prevent the spread of disease.
"Local human and animal health professionals are remaining vigilant for the occurrence of any further cases of disease caused by 'M. bovis' in humans, cats or any other pet and livestock animal species."