Naked Science Forum

Life Sciences => Cells, Microbes & Viruses => Topic started by: GAURAV on 07/12/2009 11:30:02

Title: Why is tuberculosis (TB) so hard to treat?
Post by: GAURAV on 07/12/2009 11:30:02
GAURAV asked the Naked Scientists:
Hello, my question is why is it so difficult to treat TB currently and are there any new antibiotics/ vaccines emerging? Also, does it affect other animals?

Thanks for the great show (

What do you think?
Title: Re: Why is tuberculosis (TB) so hard to treat?
Post by: litespeed on 04/01/2010 20:11:57
Tuberculosis is not difficult to treat, but individual with the disease can in and of themselves be quite difficult.

1) First, the number of individuals with anti-biotic resistent tuberculosis is small. In addition, it is not clear to me these individuals, if properly quaranteened, and supervised, and force fed with anti-biotics if need be, can not be treated anyway.

2) The only reason we probably have anit-biotic resistent strains is individuals with standard strains got to feeling better and stopped their anti-biotics before all the microbes were dead. Guess which ones survived.

3) Standard procedure in the US is to enforce full treatment through actual observation of the individual completing their course of treatment. Either through home visits or other methods.

Luckily, it is not an easily transmitted disease. But those that have it need to be physically restrained and forced to take their meds, if so required. Lock them up in jail if needed.....
Title: Re: Why is tuberculosis (TB) so hard to treat?
Post by: Bored chemist on 04/01/2010 21:14:54
Perhaps it's just me, but that looks like blaming the victim.
TB isn't easy to treat.
It takes a long time because the bacteria involved grow slowly. Since they don't do anything in a hurry you can't kill them in a hurry. Also they are coated with a waxy outer layer which makes it difficult to get antibiotics into the cell to kill it.
So the "short" form of treatment takes months.
(From Wiki)
"The standard "short" course treatment for tuberculosis (TB), is isoniazid, rifampicin, pyrazinamide, and ethambutol for two months, then isoniazid and rifampicin alone for a further four months. The patient is considered cured at six months (although there is still a relapse rate of 2 to 3%). For latent tuberculosis, the standard treatment is six to nine months of isoniazid alone"
Because it takes so long there is ample time for the bugs to mutate so the the doctors generally use several antibiotics at the same time- that way it doesn't matter if the bugs develop immunity to one of the dugs.
This combination of drugs will, of course, lead to a combination of side effects.

Most victims of TB are no more inclined to stay ill than the sufferers of other diseased but, like the rest of us they want to get on with their lives. Returning for repeated treatment for a disease that isn't causing them significant problems isn't convenient. You can hardly blame them for not doing so, particularly when they are faced with the side effects of a group of drugs..
Added to this is the fact that many TB patients are poor- they need to spend their time trying to make ends meet rather than gooing back to the doctor for what they see as pointless treatment.
Not only that, but many of them are HIV positive- they consider themselves to be living under a death sentence anyway so the TB doesn't really matter to them.
Locking them up seems to be at best a bit heavy handed; doing so because "Tuberculosis is not difficult to treat" is plain wrong.
If we spent as much on vaccination as it would cost to lock people up I suspect we would see better results.

Oh, BTW, according to the world health organisation "TB is contagious and spreads through the air. If not
treated, each person with active TB infects on average 10 to 15 people every year
Title: Re: Why is tuberculosis (TB) so hard to treat?
Post by: Geezer on 04/01/2010 22:44:03
BC, what's the current situation with vaccination. I seem to remember getting a BCG (or do I have it wrong!) when I was about 11 years old.

Are children no longer being vaccinated?
Title: Re: Why is tuberculosis (TB) so hard to treat?
Post by: Bored chemist on 05/01/2010 10:03:53
I'm not sure, but I think that children in the UK are no longer routinely vaccinated against TB.
It would hardly make sense given the incidence of TB here. On the other hand, the reason the incidence is so low is because so many of us were vaccinated. It might have made sense to continue the vaccinations.
In other areas where TB is common it certainly makes sense and the WHO are doing this with a view to reducing the overall death toll.
Curiously, they seem to think this is a better idea (and cheaper) than locking people up for a few months.
Title: Why is tuberculosis (TB) so hard ro treat?
Post by: Variola on 05/01/2010 10:19:31
BCG is not effective against all strains of TB, and for those strains it is effective against, it is not totally effective, I think the rate about 70% effective.
Most people with TB have latent TB, which although it isn't infectious when latent there is a good chance that they will later go on to develop full blown TB. When that happens the infection is spread. It is also worth noting that latent TB treatment is not curing the TB, it is just controlling it so it doesn't become full blown TB.
HIV infection has also contributed to the rise of TB infections overall, particularly in developing countries. Due to poor medical health care, restricted or zero access to drugs and lack of education, the incidence of XDR TB is on the increase too.
Title: Why is tuberculosis (TB) so hard to treat?
Post by: Geezer on 05/01/2010 20:23:13
Blimey! I'm beginning to wish I had kept my head firmly in the sand (or somewhere)  and not asked the question.