When the chest pain and racking cough of tuberculosis patient Asha (31) refused to subside even after six months of treatment, the doctor got her sputum tested again - only to find that she had developed a worrying form of the disease known as Extensively Drug Resistant TB, which is nearly impossible to treat as of now.

India is already grappling with the disease burden of Multi-Drug Resistant (MDR) tuberculosis, which manifests when a patient fails to take all the TB medicines exactly as prescribed and misses out some doses. The TB bacterium, which remains in the patient, mutates and cannot be treated with the first and second line of treatment.

The bacterium has mutated even more as Extensively Drug Resistant TB (XDR-TB) that is resistant to normal drugs. Doctors are now trying combination drugs to treat it.

According to the World Health Organization (WHO), India is home to 73,000 patients with MDR-TB. The figure for XDR-TB is not yet known.

"XDR-TB is a reality," Vivek Nangia, director (Pulmonology and Infectious Diseases) at Fortis Hospital in Vasant Kunj, told IANS.

"XDR-TB develops a couple of years after MDR-TB if it is not treated properly," he added.

According to Chand Wattal, chairman (Microbiology Department) of Sir Gangaram hospital, "unless XDR-TB is realised as a danger, the situation cannot be controlled".

The prevalence ratio of TB in India is about 1:32, according to the Tuberculosis Association of India.

India's Directly Observed Treatment Shortcourse (DOTS) strategy, which is implemented through the Revised National Tuberculosis Control Programme (RNTCP), is aimed at achieving an at least 85 percent cure rate amongst new patients.

Rajiv Chawla, senior consultant (Respiratory Critical Care) at Indraprastha Apollo Hospital, said that though the threat of XDR-TB is not absolute as of now, it can very soon assume dangerous proportions if preventive measures are not taken quickly.

Doctors also said that XDR-TB raises concerns of a future TB epidemic with restricted treatment options, jeopardizing the major gains made in TB control and progress on reducing TB deaths among people living with HIV/AIDS.

It is, therefore, vital that TB control is managed properly and new tools are developed to prevent, treat and diagnose the disease, they said.

The true scale of XDR-TB is not known as many countries lack the necessary equipment and capacity to accurately diagnose it. It is, however, estimated that there are around 40,000 cases per year globally.

As of June 2008, 49 countries have confirmed XDR-TB cases. By 2010, that number had risen to 58.

Like other forms of TB, XDR-TB is spread through the air. When a person with infectious TB coughs, sneezes, talks or spits, TB germs, known as bacilli, are propelled into the air. Inhaling even a small number of these leads to an infection.

According to Nangia: "The Indian TB treatment is not working as our population is larger...over population is adding to the problem."

Wattal said in India, "the population needs to be tracked. Family members and contacts of patients need to be tracked. In India there is no accountability, no surveillance. Patients need to be put on a data base," he said, adding, MDR-TB doesn't need long to turn into the extreme form.

One in three people in the world is infected with the TB bacteria. Only when the bacteria becomes active do people contract the disease. Bacteria becomes active as a result of anything that can reduce the person's immunity, such as HIV, advancing age or medical conditions.

Significantly, fewer people are dying of tuberculosis in Southeast Asia today compared to 1990, according to the World Health Organization. The death rate due to the disease has decreased by more than 40 percent in the past 13 years.

As access to TB care has expanded substantially, the number of people with TB, or the TB prevalence rate, has also declined by a fourth in the region compared with 1990.

All the 11 member-countries of the WHO in South Asia have adopted the WHO Stop TB Strategy. More than 88 percent known TB patients have been successfully treated.