Two people have developed tuberculosis (TB) after contact with a cat in the first ever recorded cases of cat-to-human transmission, officials have said.
Public Health England (PHE) said two people developed tuberculosis after contact with a domestic cat infected with bacteria Mycobacterium bovis.
The bacteria causes TB in cattle (known as bovine TB) and in other animals.
Nine cases of Mycobacterium bovis infection in domestic cats in Berkshire and Hampshire were investigated by the Animal Health and Veterinary Laboratories Agency (AHVLA) and PHE last year.
PHE said it had offered TB screening to 39 people identified as having had contact with the nine infected cats.
Of these, 24 people accepted screening. Two were found to have active TB and there were two cases of latent TB, which means they had been exposed to TB at some point but did not have an active infection.
Both people with active TB disease have confirmed infection with Mycobacterium bovis (M. bovis) and are responding to treatment.
PHE said there there have been no further cases of TB in cats reported in Berkshire or Hampshire since March 2013 and said it believed the risk of transmission from cats to humans was "very low".
Analysis of the samples of active TB from the humans and the infected cats by the AHVLA showed the M. bovis was "indistinguishable".
This "indicates transmission of the bacterium from an infected cat", PHE said.
In the cases of latent TB infection, it was not possible to confirm if they were caused by M. bovis.
According to PHE, transmission of the bacteria 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".
Dr Dilys Morgan, head of gastrointestinal, emerging and zoonotic diseases department at PHE, said: "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.
TB is a serious condition but can be cured with proper treatment, namely antibiotics taken for at least six months.