The World Health Organisation has warned that a form of tuberculosis resistant to antibiotics has emerged which it says is 'virtually untreatable'.
The WHO has called for reinforced measures to avoid the spread of deadly strains of the disease.
A recent study focused on an ultra-resistant form of TB which leaves patients, particularly those with HIV, untreatable using currently available anti-TB drugs.
TB has the potential to spread very rapidly in HIV-positive individuals and there is a very high mortality rate among patients.
A WHO statement warned that given the underlying HIV epidemic in Africa, drug-resistant TB could have a severe impact on that continent.
The new strain is resistant to at least three of the categories of medicine prescribed when a patient fails to react to initial tuberculosis antibiotics.
A meeting of experts this week in Johannesburg, South Africa, is due to evaluate possible measures to deal with the problem.
Such ultra-resistant strains of TB occur most frequently in former Soviet countries and Asia and are on the rise elsewhere, particularly in Africa.
