International researchers say they have
made a "significant step" towards a predictive blood test for
tuberculosis.
A DNA fingerprint in the blood shows
promise in identifying which carriers of TB will go on to get symptoms and
spread the infection.
Such a test would allow earlier
diagnosis and treatment of the lung disease, potentially saving many lives.
Experts say the research, published in
Nature, is "remarkable" but needs to be proven by further work.
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| X-ray of the chest of a patient with TB |
Tuberculosis, or TB, is an infectious
bacterial disease of the lungs, causing symptoms such as coughing, chest pains
and weight loss.
Someone in the world is newly
infected with TB every second, with nearly 2 million deaths each year.
Only around one in 10 people infected
with TB go on to develop the active form of disease.
Currently, although a skin or blood
test can show if someone is harbouring TB, but not showing symptoms, it is
impossible to predict who will get the full-blown disease.
Researchers from the UK , US and South Africa
The same genetic markers were found in
about 10% of patients with latent infections, suggesting they are candidates
for the full-blown form of the disease.
These patients will now be followed up
in the future, to see if they do go on to get symptoms.
Promise
Lead researcher Dr Anne O'Garra of the
MRC's National Institute for Medical Research in London
She told the BBC: "If you could
predict which so-called carriers of TB will progress to the full-blown disease,
this would have major ramifications for stopping the global epidemic.
"We just have to prove it now, but
it's very promising."
Mike Mandelbaum, chief executive of the
charity TB Alert, said good progress had been made in the diagnosis of latent
TB infection in recent years, but there was a need for a specific test for the
active disease.
The diagnosis of TB is often difficult
to make until the disease has become infectious to others, he said,
particularly in the developing world which has fewer resources.
"A new diagnostic technique based
on a blood test would be extremely valuable to save lives and prevent the
spread of this disease," he said, "and may be particularly important
in HIV positive patients with TB where the usual technique of diagnosis from
sputum is often unhelpful."
Dr Marc Lipman, chairman of the TB
special advisory group at the British Thoracic Society, said it was "a
remarkable piece of research".
He explained: "This for the first
time perhaps enables us to start to design tests which can predict who is at
highest risk of progressing to active disease and also how we might stop that
occurring in the first place.
"Any such advance is 20-30 years
away," he added.
Tuberculosis: (Source - World Health Organization/HPA)
- Tuberculosis is an infectious disease, which usually affects the
lungs
- It is transmitted via droplets from the lungs of people with the
active form of the disease
- In healthy people, infection often causes no symptoms
- Symptoms of active TB include coughing, chest pains, weakness,
weight loss, fever and night sweats
- Tuberculosis is treatable with a course of antibiotics
- In the
Source: BBC. By Helen Briggs. 18 August 2010
