Some facts about extensively drug resistant tuberculosis, more commonly known as XDR-TB:
What is it? — Strains of tuberculosis bacteria that have developed resistance to most of the drugs used to treat the disease.
How does it arise? — Most cases are the result of failed treatment for regular or multi-drug resistant TB. If patients don't take the full course of antibiotics, the bacterium can evolve to evade the power of those drugs. But people can also be infected directly with an XDR-TB strain.
Is it curable? — Yes, but only in some cases. The CDC estimates that 30 per cent of people infected with XDR-TB are cured. In people with HIV-AIDS, however, the infection is generally fatal; 90 per cent of these cases die.
How is it spread? Like regular TB. Infected people spew out the TB germs when they cough, sneeze or even speak or sing. Persons who breathe in the air containing these TB germs can become infected, though it is believed people who have fleeting contact with a case aren't at much risk.
Does everyone who contracts TB get sick? Only between five and 10 per cent of people who are infected come down with active disease. The rest have what is called latent infection and they are not infectious to others. The World Health Organization estimates a third of the world's population is infected with TB.
