Latent Tuberculosis: Indian TB germ not aggressive, says expert
By Syed Akbar Hyderabad, April 23: If the Lancet's recommendation on latent TB is to be implemented bythe UK and other developed nations like the USA, every Indian, who wants to visit thesecountries, may have to undergo nine-month-long medication for latent TB. According to bacteriologists, since 75 per cent of latent TB cases are difficult to bedetected or likely to be mis-diagnosed, as a precautionary measure every Indian suspectwould be made to consume latent TB medicines. This will put a heavy financial burden onindividuals and create unnecessary resistance to TB, if the person does not carry latentTB germs. Moreover, even active TB germ in India is "shy" in the sense that it does notspread as aggressively as its counterparts in other countries. "Suggesting that a person undergo tests for latent TB and putting him on medication is agross violation of human rights. Unless you find the bacteria in the sputum or the lungdamaged, you cannot ask him or her to take medication, which is highly toxic and causeharm to liver. Moreover, diagnosis and treatment of latent tuberculosis are bothdifficult and uneconomical," warns Dr Niyaz Ahmed, senior pathobiologist and Professor(adjunct), Institute of Life Sciences, University of Hyderabad. Lancet's recommendation is easily said than implemented. A number of ethical and medicalissues are involved in treating people with latent TB. According to Dr Niyaz Ahmed, the Monteux test based on skin reaction to mycobacterialprotein components is seriously cross-reactive and could produce false positive and false negative results in case of 70 per cent of the Indians. Similar difficulties could beencountered with another test called Interferon-gamma test. India has so far not experienced any institutionalised outbreak as against the famousfatal outbreaks of New York and Kwazulu Natal. That means the Indian strains are lessaggressive and controllable. Indians enjoy a distinct natural protection from latent TBdue to the facts that their genetic makeup is different, their strains are different andtheir immune system is already primed due to a saprophytic antigenic background and/or by Helicobacter infection. The UK should therefore, not be worried for Indians. They should in fact be worried aboutthe Pakistanis and Sri Lankans, who do not have the ancestral strains of TB bacteria(TbD1+) in their countries and could proceed to full blown TB more rapidly than Indians,he said. Anti TB drugs are poisonous to liver in long course and low dosage or short course couldselect out drug resistant bacteria. Stating that it has become a fashion in the West toproject India as a source of infection, he said the story is worst in case of countriesthat are dubiously known for their highly virulent multi-drug resistant and extremelydrug resistant strains such as South Africa, Russia and the countries of the former USSR. "In fact, the UK should happily give immigrant status to Indians because it is provedalready that the Indian strains of Mycobacteria are of ancestral type (genotype TbD1+)and the treatment success rates of up to 95 per cent have been recorded under the DOTSprogram. These strains are theorised as ‘shy’ in terms of dissemination as compared tosome of the very aggressive genotypes such as Beijing, Africa and Haarlem," Dr NiyazAhmed said.