KHOPOTSO: According to an MRC survey on a sample of MDR-TB patients in 2002, it emerged that 55% of the participants who had the drug resistant TB were also infected with HIV. The result from that sample has led to the Department of Health concluding that half of all South Africans infected with TB also have the HI virus. Current projections by the Medical Research Council put the figure at 66.4%. In an effort aimed at dealing with the dual epidemics of HIV and TB, the Department of Health has since set up a TB-HIV collaboration unit. As HIV is one of the predisposing factors to TB infection, the guiding principle of this unit is that every person who tests positive for tuberculosis should be encouraged to take the HIV test as well. The national AIDS treatment guidelines recommend that if one is found to be HIV-positive, at some stage during infection, they should take prophylactic medication to prevent TB. Dr Lindiwe Mvusi is the manager of the national Tuberculosis Control Programme in the Department of Health.

Dr LINDIWE MVUSI: Being on antiretrovirals just simply is not preventive of the person getting TB. The main thing is that if you’€™re still exposed to a person who is infectious you will get it. But there is TB preventive therapy that is available for HIV-positive individuals, which they can then take for a period of six months. It’€™s mainly one drug that is used to treat TB ‘€“ Isoniazid ‘€“ taken daily for a period of six months.

KHOPOTSO: This is a precautionary measure and it’€™s still unclear as to whether the six months of TB prophylaxis is enough to prevent one from ever catching TB.

Dr LINDIWE MVUSI: There hasn’€™t been much work in terms of research to prove whether now is six months sufficient or should we be giving it for a longer period, 12 months or even for life’€¦? We’€™re still waiting for more evidence in terms of benefits of TB preventive therapy.

KHOPOTSO: In the meantime, there is debate on the safety of putting people on the TB drug, Isoniazid simply to prevent them from getting tuberculosis. Anna-Marie Daniel is the matron of the South African National Tuberculosis Association (SANTA) hospital in Springs, east of Johannesburg.

ANNA-MARIE DANIEL: My question will then be: If a patient after the six months does get TB, what medication are we going to use to cure his TB? What if a patient builds up resistance towards your TB medication? Then we won’€™t have anything to treat him with if we start making people resistant to the only few drugs that we’€™ve got to cure TB.

KHOPOTSO: Dr Desmond Martin, President of the South African HIV Clinicians’€™ Society has experience in using the TB prophylactic therapy.

Dr DESMOND MARTIN: I dare say that certainly the risk does exist. We always face, in medicine, resistance by organisms to mono-therapies. We saw it with HIV and seen it with the other conditions as well. So, INH, because it’€™s a mono-therapy, I would argue that this could occur. But I’€™m not sure whether data has borne this out. And certainly, international organisations haven’€™t warned against the use of INH in this context, which I’€™m sure would be the case should it have proved to be problematical in the resistance arena.

KHOPOTSO: The risk profile of using Isoniazid as a single intervention in TB prevention may have not been determined. But what of the mechanism’€™s efficacy profile?    

Dr DESMOND MARTIN:  I think that the meta-analysis of studies where INH prophylaxis has been carried out show that there is benefit in using this. But the benefit would appear to not last longer than about a two-year period. It should be used at that critical phase where you’€™re tidying people over before they go on to the antiretrovirals. And that in itself has been shown to be a very important prevention of tuberculosis ‘€“ by treating HIV itself and reconstituting the immune system and then, preventing the breakthrough of these dormant organisms.

KHOPOTSO: But it’€™s not every HIV-infected individual who is eligible for Isoniazid.

Dr DESMOND MARTIN:  We believe it should be given at a particular time. Now this time is when the immune system is measured by what we call a CD 4 count, decreases to a level below 350. We know that’€™s when tuberculosis usually starts to appear. Now, as most of our antiretroviral rollout programmes in South Africa start, when the CD 4 count is 200 or less, it means that our patients are going to be vulnerable’€¦ those certainly with CD 4 counts between 200 ‘€“ 350 to develop tuberculosis.

KHOPOTSO: Dr Martin believes that to prevent a dual infection of HIV and TB the eligibility criteria based on an individual’€™s CD 4 count level should be increased from 200 to 350. This, he says, is also necessary because the Isoniazid intervention on its own is not full-proof in preventing TB infection.      

E-mail: Khopotso Bodibe