Tuberculosis (TB) strikes more than 2 billion people across the planet, and US scientists have made a breakthrough they say could save hundreds of thousands of lives.

Effective drugs have been around for 50 years, but TB is far from eradicated.

US scientists have now found that tuberculosis can lurk in human bone marrow cells and then re-emerge as an active disease.

Of the 2.2 billion people infected with tuberculosis, most have the latent version; they don't have symptoms and don't know they have it.

The disease, which most commonly affects the lungs, is transmitted via the air and caused by strains of mycobacteria.

The active version surfaces when the immune system is affected - by old age, diabetes or HIV - and every year it is thought to kill the equivalent of Perth's population - 1.7 million people.

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It has long been thought the reason so many people have the disease is the because of bacteria surviving somewhere in infected people who'd had the virus, but had been treated.

Now a study in the Science Translational Medicine journal has proven the bacteria can lurk in bone marrow stem cells.

Dr Steve Hambleton, the president of the Australian Medical Association, says the find is "significant" because it is the first time living TB has been found in a patient who has been treated for six months.

"It may actually help us in working out why recurrences occur. We may actually be able to find out how to stop them from recurring. It is a huge global health problem," he said.

Dr Hambleton says there could be broader implications beyond tuberculosis.

"When we look at immune competent cells, they have a great role to play in cancer and infections and it could be that spin-offs from this bone marrow research help us with cancers that are actually huge problems in our world as well."

Doctor Iven Young has treated about 800 people with tuberculosis over 35 years working in clinics in Australia.

Dr Young says TB will cause people to become weaker and weaker, with continuous and often bloody coughing as the lungs become more infected.

Australia has one of the world's lowest rates of tuberculosis. Dr Young says most of those he's treated have migrated from India, China, South-East Asia or the Pacific Islands.

"The patient becomes more and more fatigued, continual coughing, and weight loss," he said.

"Weight loss which is extraordinarily dramatic in the later stages, and hence the disease was given the term consumption a century ago, because it seemed the body was literally being consumed from the inside out.

"Patients dying of tuberculosis were invariably extraordinarily thin."