What with Pasteurisation and vaccination you could be forgiven for thinking TB was a thing of the past. But you’d be wrong. And it’s the fluffy vermin to blame yet again. Bastards. I’ve already written about how they make you wreck your car. Now they give you TB as well as a host of other zoonoses (diseases we catch from critters).
There are a bunch of different mycobacteria; yer classic TB is caused by Mycobacterium tuberculosis (Mtb) but the FVATB (Fluffy Vermin-Associated TB) in this case was caused by its cousin, M. bovis. The data suggest it’s a rare event to get this from animals in developed countries but it’s rife elsewhere; a study in Mexico looked at the incidence of latent and pulmonary TB in dairy and abattoir workers and their families and found incidences of 60-80% depending on how you measured it. Either way that’s a big number.
There’s also been a big rise in non-TB wound infections on the other side of the pond. BFLATB (Bat Fastard Liposuction-Associated TB) has been linked to medical tourism to the Dominican Republic – go and get your tits / arse / whatever done, catch some rays and bring back an unexpected souvenir…
Back to M. bovis, our pussy-borne scrofula du jour.
Most M. bovis infections in humans are attributed to people who voluntarily drink sewage or feed it to their unsuspecting offspring. And yes, people do feed sewage to their kids. I can only imagine they do this because they think disease or deformity is character building; I’ve dealt with ‘raw’ milk elsewhere but forgot that historically extrapulmonary TB via the oral route often caused bone infections resulting in hunched backs.
But what about TB? It still lurks in the UK predominantly in those from countries with high TB burdens and those with social risk factors, but what are the risks of catching TB from pussy? Well, provided you avoid cheap Latin-American liposuction, put the Fluffy Vermin in the nearest autoclave and try to avoid carnal relations with farmyard animals you should be OK. And avoid raw milk, obviously (but there’s stuff in that which’ll kill you faster than TB).
The mycobacteria are an oddball group – they don’t Gram stain properly which pisses microbiologists right off and many species can cause disease in animals, generally of three basic flavours:
- Tuberculosis: the term used to describe disease where granulomas (inflammatory lumps) form in the body, usually the lungs
- Leprosy: infection leads to formation of granulomas in the skin
- Opportunistic infections: these are infections that usually involve subcutaneous tissue (just below the skin) – these can be due to accidental trauma, tattooing or Utter Utter Bollocks (µ²B) like mesotherapy or acupuncture.
Let’s take a closer look…
Mycobacterium tuberculosis (Mtb)
Causes most cases of tuberculosis in humans and we are the only reservoir for it; Mtb rarely infects other mammals and cats are naturally resistant (bastards!). Other mycobacteria can cause pulmonary TB and Mtb can turn up elsewhere, though. This was the ‘White Plague’ of the 17th and 18th centuries where pretty much all of Europe was infected (and probably most other places too). A quarter of all adult deaths were caused by Mtb and it went under many names: pthisis, scrofula, lupus vulgaris, consumption and the Captain of the Men of Death.
Geek note: don’t forget the Black Plague was very different disease, caused by Yersinia pestis and about 300 years earlier.
We gave Mtb to cows about 40,000 years ago and it came back as M. bovis. It causes TB in cows and was considered to be rare in humans – but not as rare as we thought, obviously. Cows and humans are known reservoirs but others including deer, badgers, ferrets, dogs and cats get it too.
If you culture M. bovis repeatedly in a glycerin – bile – potato medium for about a decade you end up with BCG: the attenuated strain used to vaccinate against TB. (This is how you make attenuated strains of a vaccine: grow them up repeatedly in something else, usually another animal, it then becomes less infective in humans but still looks enough like the human strain to get your immune system going without getting the human disease).
This causes leprosy. Mtb and leprosy diverged about 40 million years ago – long before we were about.
M. avium complex (MAC) is a group of related mycobacteria widespread in animals and in the environment that cause a TB-like illness especially in AIDS patients. M. avium intracellulari (MAI) is found in water everywhere. Associated with HIV and hairy cell leukemia. Has been associated with puncture wounds and non-AIDS lung disease.
There are too many other mycobacteria to list; they are ubiquitous and found in soil or water and can infect by trauma (inc tattooing) or by inhalation. There are different mycobacteria that infect most mammals and many can switch hosts. Other tuberculosis-causing mycobacteria found in cats include M. microti – cats catch it from voles and other rodents if they hunt actively but you also see M. avium complex (MAC) causing disseminated granulomas.
But have you heard of M. jacuzzii? I’m not making this up, honest. This novel strain was identified in 15 women with post-op infections after having breast implants.
It was traced back to the surgeon’s Jacuzzi. And no, he didn’t do the surgery in the hot tub. Might have got a better result of he had, though. And although this happened in America I can’t resist pointing out that the British Association of Prosthetic Plastic Surgeons could have come up with a better acronym than BAPPS.
Or perhaps not…