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Friday, March 30, 2007

Studying the prevalence of HIV in TB patients

EVEN AS "Difficulties in working alongside the better-funded efforts to tackle AIDS permeate many aspects of TB prevention, treatment and research ... " as the Editorial in the latest issue of Nature points out, the scenario in India is changing for the better.
With their immunity compromised, TB is one of the most common opportunistic infections in those with HIV/AIDS. And such coinfection often proves fatal.
Greater possibility
And with a total TB burden of 8.5 million as per 2000 estimates, and almost 1.8 million new cases occurring every year, the chances of over 5 million HIV positive people getting TB are quite high.
It is to address this problem that the prevalence of TB in HIV infected people, and HIV in those with TB are being studied in India.
Earlier, TB patients were provided with information to get tested for HIV. But there was no way of ensuring that patients indeed went for the HIV test.
"We lost many patients in the process," noted Supriya Sahu, Project Director, Tamil Nadu State AIDS Control Society (TANSACS).
The National Surveillance Survey conducted by the Central TB Division is under way to address this problem. The surveillance survey has been expanded to cover 20 districts in the country, with two being in Tamil Nadu, and has been designed to test for HIV in all the newly diagnosed TB patients.
This would help understand the prevalence of HIV in newly diagnosed TB patients.
The study in two districts in Tamil Nadu — Thiruvannamalai and Villupuram — started in December last year.
Automatically tested
This is a pilot study where every newly diagnosed TB patient is automatically tested for HIV at the designated microscopy centres and is unlike the earlier scenario when healthcare providers used their discretion to decide who should be asked to go for HIV testing.
The two districts in Tamil Nadu where the surveillance will be carried out will be operational till 400 samples are collected from each centre. "All newly diagnosed TB patients and who are already on DOTS (Directly Observed Treatment, Short-course) for two months will be tested for HIV," said Ms. Sahu.
Unlike the conventional practice, the newly diagnosed TB patients will neither be informed nor their consent taken before they are tested for HIV.
But is testing for HIV without the patients' knowledge ethical?
"It is an unlinked and anonymous HIV testing," she explained. "The samples will be coded and nobody will ever know the patients' HIV status. So there is no need to take the patients' consent. We are following the WHO protocol." The only parameters that will be known are the age and sex of the patients and their TB status.
But will zeroing in on newly diagnosed TB patients alone be a truly representative sample? "Nearly 80 per cent of those who come for testing to designated microscopy centres are new cases," said Dr. Soumya Swaminathan, Deputy Director, Tuberculosis Research Centre, Chennai.
Another study
A similar study to understand the prevalence of HIV in newly diagnosed TB patients was undertaken in 2005-2006 by Dr. Swaminathan. The study funded by TANSACS looked at four districts — Kancheepuram, Villupuram, Chennai and Vellore — in Tamil Nadu. Unlike the surveillance study undertaken by TANSACS, Dr. Swaminathan's study did not collect blood samples for HIV testing from the newly diagnosed TB patients. Instead, they were provided with information and counselled to get tested for HIV.
"One of the objectives of our study was to see the level of acceptance by TB patients to getting tested for HIV," Dr. Swaminathan explained. "And we found that about 70 per cent of TB patients were convinced of the virtue of getting tested for HIV."
People who did not go in for HIV testing were those who considered themselves as too old to get infected with HIV or were not at risk of getting infected. "Women generally considered themselves not at risk," she noted.
Studying co-infection
Another study that TANSACS intends to undertake in Tiruchi district, Tamil Nadu, is to see the level of co-infection with HIV and TB. Patients diagnosed with TB will be sent to voluntary counselling and testing centres (VCTC) and all who test positive for HIV will be sent to designated microscopy centres to check for their TB status.
The study on co-infection will be the first of its kind in the country. "This will not be a surveillance study," Ms. Sahu said. The protocol for the study is yet to be drawn up.
Under the joint TB-HIV action plan started in 2005 by NACO in six high prevalence HIV States, including Tamil Nadu, those coming to VCTC for HIV testing and suspected of having TB are referred for TB testing.
The second, third and fourth quarter results of the 2005 joint TB-HIV action plan found that of the 6,055 persons from the six states who tested positive for HIV, 1,601 were also infected with TB.
This highlights the seriousness of coinfection with HIV/AIDS and TB in people living in India. And it is only to be expected as the prevalence of HIV/AIDS and TB is high in the country.
Showing the way
India, South Africa and a few other countries are indeed showing the world and international bodies, including the WHO, on the ways of tackling the problem and working in a more coordinated manner.
Researchers in India working on TB, much like their counterparts in other countries, still do not get generous funding unlike those working on HIV/AIDS, and unlike HIV/AIDS, TB has failed to attract the kind of attention it deserves.
But these conditions have not stopped the researchers from starting to work in a more coordinated manner. That is good for India and those suffering from HIV/AIDS and TB.

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