This article originally appeared in Positive Nation, issue 100
Dr Anton Pozniak, a consultant at London's Chelsea and Westminster Hospital and TB/HIV expert, talks to Susan Cole about TB and HIV co-infection
Tuberculosis or TB is sometimes regarded as a romantic 19th century disease. Famous victims include all three Brontë sisters, Keats and Chopin.
However more people are dying of TB in the world today than at any other time in history: over two million each year. HIV has increased TB rates in some countries fivefold. Left untreated HIV/TB is a deadly combination. The Director General of the World Health Organisation (WHO), Jong Wook Lee, has compared the effect of HIV on TB as "Like putting a match to petrol".
The WHO has announced a plan to expand collaboration between HIV and TB programmes to curb the growing pandemic of TB/HIV co-infection. "With effective treatment TB can be cured, HIV managed, and the health of millions of people preserved," Dr Lee said.
One third of the world has got TB infection. That means they have breathed in the TB bug and it has lodged in their body somewhere. Once it gets in there it might have caused a bit of disease in childhood, such as a respiratory illness. They usually get over this, but the bug remains resident in the body. In TB disease the bugs start multiplying again and causing illness.
Most of TB is transmitted through the air you breathe and comes out of people's lungs. When TB does cause disease it causes holes in the lungs that fill up with bugs. When people cough the bugs come out, spread through the air and are breathed in by someone else. There are other ways that TB can be transmitted but these are quite rare: it can be transmitted via wounds and even be transmitted sexually, but that's incredibly rare.
Most people who get TB suffer from fevers, sweats and weight loss. Otherwise it depends on what part of the body it has affected. If it's affected the lungs you'll have a cough, produce phlegm and sometimes cough up blood. If it's affected the lymph glands they enlarge. If it affects other parts of the body like the brain you may slowly become unconscious or have fits.
Yes, it's increasing slowly in the UK even though it should really be disappearing. There are many reasons for that: poverty, an ageing population and HIV, have all played a role in the UK. Worldwide it's the most common infection affecting people with HIV and it's increasing quite rapidly in some parts of the world, almost always because of HIV disease.
There's no difference in the amount of TB someone with HIV is breathing in, but once TB gets into their body, instead of the body warding it off, the immune system doesn't work as well in HIV positive patients, and therefore the TB bug starts to grow and grow and cause disease. If someone had TB when they were a child and maybe didn't even know about it, they still have some bugs in the body that occasionally wake up and are dealt with by the immune system. If they wake up and the patient is HIV positive and the immune system isn't working properly, the bugs aren't dealt with and cause disease. It's said that if you breathe in a TB bug, the risk of developing TB disease is about 10 per cent. If you're HIV positive, that risk becomes a near certainty - it's almost inevitable that you'll develop TB disease if you have a very weakened immune system. Probably the risk to an HIV positive person is 60-80 per cent.
This is a very contentious issue. WHO used to have this as one of its big thrusts forward. It doesn't anymore. What I can say is that the data shows that if you have a skin test and the skin test comes up as positive, preventative therapy works. However it doesn't work for very long. Once you stop the preventative therapy your risk goes up of breathing in some TB from the outside and becoming unwell.
Obviously tackling poverty and overcrowding is important. The other thing to do is to go on antiviral therapy if you have a low CD4 count.
Commonly we see people who have lived, worked or were born in developing countries where TB is endemic and then got HIV. But we do have a group of patients from southern Europe, some of them injecting drug users, and we do have people who you wouldn't think have a high risk factor of contracting TB, like people born in the English home counties who come in with TB. This is probably because they've travelled or worked somewhere and have been exposed. Occasionally it does occur in hospitals and you can get transmission in healthcare settings.
Well the best thing is to look at the spit and if you see the bugs in the spit, you culture the bugs and see if they grow as TB. In HIV negative patients it works in 50-60 per cent of patients. In HIV positive patients they don't tend to form holes in the lungs and it's more difficult to see the bugs in the spit. The TB bugs may be trapped inside the lungs, so it's less easy to diagnose. However if positive patients present with big glands you can easily get the bugs out of the glands and if you're very immuno-suppressed, you can even see them in the bloodstream, so it's a case of looking hard.
Yes. Either by one doctor who knows about both, or two doctors who know about each of their sections. TB is much better treated by people with experience of TB, and of course we know that HIV is a very complex disease needing specialist care. If you put the two diseases together you have lots of issues, not just the social and psychological issues, but also things like contact tracing for TB.
Then there are drug interactions between many of the HIV drugs and TB drugs, side effects and curious things like TB symptoms reappearing when the immune system recovers - so-called Immune Reconstitution Inflammatory Syndrome - so you really need a multi-disciplinary team. You need two teams to work together unless, as in my case, you have someone with experience in both, and their team covers both.
There are standard guidelines and if you have a drug-sensitive TB you should have a cure rate of about 98 per cent. The standard drug regime is usually rifampicin, isoniazid, ethambutol and pyrazinamide for two months, then isoniazid and rifampicin for four months.
The guidelines are being developed, but at present it's an unknown question. What we would say is that if your CD4 count is above 200, treat the TB first because there's no rush to start the HIV therapy. If your CD4 count is very low there is some data that suggests you treat both TB and HIV together. You've always got to treat the TB because it's a public health issue. So it's a question of when to give the HIV drugs. I would say, if you've got a very low CD4 count, the risk of developing Aids is high, so you would probably need to start HIV therapy as well as TB therapy. If your CD4 count is between 100-200, you could easily wait a couple of months before starting HIV therapy and be given medication to prevent PCP.
Rifampicin is an essential drug in TB therapy. It induces the liver enzymes, which means it makes the liver break down other drugs more effectively. So if you give rifampicin with a drug that is broken down by the liver enzymes, such as nevirapine or some of the protease inhibitors, these drugs won't work effectively. You would therefore run the risk of virological failure.
It's unusual in the UK to find multi-drug-resistant (MDR) TB. It's less than half to one per cent of TB cases, depending on where you are in the UK. MDR-TB is defined as TB resistant to both rifampicin and isoniazid. About 10 per cent of TB in this country is resistant to isoniazid alone, so that's more common. The way you get resistance is if the drugs aren't given to you in the right doses, you don't take your drugs properly or you pass this strain on to somebody else and they get it (a bit like HIV).
Yes, there are. You can use the familiar BCG vaccine - it depends on which country you are in as to whether or not it works. There are a number of reasons for this. In the UK, the long-term prevention of TB by BCG is about 70 per cent. However you can't give BCG to people who are HIV positive. There are other vaccines being developed at the moment to try to prevent tuberculosis.
Well I don't think it's practicable. There is screening for new migrants to this country, but even that is done under a lot of difficult circumstances. Someone may not get screened at Heathrow because they're being screened somewhere else, then give an address and when they're contacted they may have moved on from there. It's very, very difficult. It's a big public health issue.
Susan Cole reports back on the Stop TB Partners Forum in New Delhi in March 2004. The UKC's Knowledge is Power Project also launched awareness campaigns on Hepatitis C and HIV co-infection and TB/HIV co-infection.
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