Q & A on tuberculosis
Tuesday 18th March
TB Alert's Professor Peter Davies is a consultant chest physician at the Liverpool Heart and Chest Hospital. Ahead of World TB Day in March, he shares his expertise on tuberculosis and the multidrug-resistant strain of the disease.
How did you come to specialise in tuberculosis (TB)?
I've had an interest in TB from the time I was a junior doctor. I was a member of the Medical Research Council's TB unit from 1978 to 1980 and that's given me a life-long interest in it. Within chest medicine it's an important specialty. There are relatively few of us with any ongoing expertise, because it appeared to die out. It never did – but people had the perception that it had by the mid 1980s.
Is TB generally treatable?
Yes, it is, and except for drug resistance we get 95 per cent success. The standard length of treatment is six months; with multidrug-resistant (MDR) tuberculosis it's two years.
What are the main complications with MDR?
Failure of treatment, leading to death. The failure rate with fully sensitive TB is five per cent max; with multidrug-resistant it's more like 20 per cent.
Is resistance caused by overuse of antibiotics?
It's due to misuse of antibiotics. The overriding problem is that TB has to be treated with several drugs over several months, and the temptation for the patient is just to take one or two that they don't mind taking, and leave the ones that have side-effects. And so we've built up resistance, particularly in the Soviet Union and Eastern Europe and parts of India where there's been huge mismanagement, but also Africa as well, for reasons we don't really understand.
If you are treated with one drug you develop resistance to that. And if you were then to be treated with two drugs – one you are resistant to and a new one – you become resistant to the second and so you can build up resistance in this way. And that's why we have extreme drug resistance in some parts of the world, where there isn't really a drug available for proper treatment. Which is terribly sad.
Is medical research making any headway?
I think it's highly likely that this year, for the first time in 40 or 50 years, we will have a new drug and a new drug regimen for TB. The modern regimen which we use for TB is rifamycin, isoniazid, ethambutol and pyrazinamide. That regimen has really been used since 1980 and these drugs, rifamycin being the last, have been available since 1970. We stopped developing new drugs completely in the 1970s and 80s, when it was thought that it was defeated, at least in the West. But it certainly wasn't.
Now, after 44 years of waiting, we're likely to get a new regimen for TB. I hope that we'll have two regimens actually. One will be shorter than six months, maybe a four-drug regimen and, secondly, a regimen that will improve the prognosis for drug-resistant cases (to 95 per cent). I think these two things could happen soon, because of the developments that have taken place over the last 20 years.
TB Alert, the UK’s national TB charity, is raising awareness of tuberculosis to mark World TB Day in March. Visit the website to learn about the important work the charity is doing in the UK, India and Africa.
Find out more about the symptoms of TB.