“Could you catch TB from YOUR tabby?” (The headline in the Daily Mail) As a microbiologist and an owner of 5 cats, I had to blog on the news that cats have infected their owners with Tuberculosis!
The outbreak occurred between December 2012 and April 2013. The limited details published by Public Health England are that 9 cats from the same location in Berkshire were diagnosed with Mycobacterium bovis infection and have transferred this infection to their owners.
The outbreak occurred between December 2012 and April 2013. The limited details published by Public Health England are that 9 cats from the same location in Berkshire were diagnosed with Mycobacterium bovis infection and have transferred this infection to their owners.
This unusual occurrence prompted an investigation by human and animal health protection agencies. All of the cats showed evidence of having recently been in fights. Of the 39 household contacts of the 9 cats, 24 were screened for tuberculosis using interferon gamma release assay(IGRA) blood tests. Reactive tests were found in 4 contacts, 2 of whom had active infection with M. bovis and 2 had latent tuberculosis infection (as much as can be concluded from a reactive IGRA test in someone who remains asymptomatic).
Molecular analysis of the organism from the cats and the humans showed the DNA could not be distinguished and therefore it is likely that for the first time ever reported there has been transmission of tuberculosis between the species. The patients received standard TB treatment; the unfortunate 9 infected cats were euthanased.
Molecular analysis of the organism from the cats and the humans showed the DNA could not be distinguished and therefore it is likely that for the first time ever reported there has been transmission of tuberculosis between the species. The patients received standard TB treatment; the unfortunate 9 infected cats were euthanased.
M. bovis is one of a group of related bacteria collectively called the MTB complex.
Click for larger image
Human infection with M. bovis is very unusual (only 35
cases being diagnosed in the UK in 2012) compared to M. tuberculosis which is relatively common (an estimated 90,000 cases per year in the UK) although 90% of patients are asymptomatic. The clinical features and treatment of
M. bovis are no different from other forms of tuberculosis.
Clinical Features
cases being diagnosed in the UK in 2012) compared to M. tuberculosis which is relatively common (an estimated 90,000 cases per year in the UK) although 90% of patients are asymptomatic. The clinical features and treatment of
M. bovis are no different from other forms of tuberculosis.
Clinical Features
Click for larger image
Treatment
Click for larger image
Despite the headlines “More people will catch TB from their cats, top vet warns” (The Telegraph) an outbreak of this type has never happened before and is considered to be a very low risk to public health. The transmission of infectious microorganisms from animals to humans is not new; they are called zoonoses. However, the story does highlight the microbiological link between humans and animals. The cat is not the only species to cause medical conditions where owners acquire microorganisms from their pets. Examples include: Mycobacterium marinum in aquatic pet owners, psittacosis in pet bird owners, Toxocara canis in dog owners, salmonella in reptile pet owners and The Black Death in rat owners...or more likely rat bite fever! Historians have concluded that zoonotic infections are an inevitable consequence of human evolution from hunter gatherers, who moved frequently and had little or no social contact with animals, to settled agriculturalists with close bonds with their animals.
There is a lack of knowledge about the normal flora of pets and their owners. I believe that if a study was conducted into this normal flora we are likely to find that it is a two way street with humans giving as many bacteria to our pets, not just the other way around.
“I talked to my cat about this problem. I told him I might have to cull him. He said I could try but he would still have
eight lives left” (comment left on The Telegraph website).
In truth, the cynic in me thinks that the announcement of the proposed national TB strategy got very little media coverage on the 24th March 2014 so the “My cat gave me TB” story was broken a few days later, even though the outbreak occurred over a year ago. It has done the job though and highlighted TB and zoonotic infections and I don’t think that’s a bad thing.
You'll be glad to know that no cats were harmed in the writing of this blog....
There is a lack of knowledge about the normal flora of pets and their owners. I believe that if a study was conducted into this normal flora we are likely to find that it is a two way street with humans giving as many bacteria to our pets, not just the other way around.
“I talked to my cat about this problem. I told him I might have to cull him. He said I could try but he would still have
eight lives left” (comment left on The Telegraph website).
In truth, the cynic in me thinks that the announcement of the proposed national TB strategy got very little media coverage on the 24th March 2014 so the “My cat gave me TB” story was broken a few days later, even though the outbreak occurred over a year ago. It has done the job though and highlighted TB and zoonotic infections and I don’t think that’s a bad thing.
You'll be glad to know that no cats were harmed in the writing of this blog....
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