WHO CALLS FOR ACTION ON DRUG-RESISTANT TB STRAINS

The World Health Organization (WHO) has expressed concern over the emergence of virulent drug-resistant strains of tuberculosis (TB) in Africa and is calling for measures to be strengthened to prevent the global spread of the strains. This follows research showing the extent of the spread XDR-TB, a newly identified strain that leaves patients virtually untreatable with current anti-TB drugs.

The WHO plans to meet with TB experts in South Africa to assess the response required to address TB drug resistance.

Multidrug-resistant TB (MDR-TB) describes strains of tuberculosis that are resistant to two main first-line TB drugs -- isoniazid and rifampicin. Extensive drug-resistant TB (XDR-TB) is MDR-TB that is also resistant to three or more of the six classes of second-line drugs. This strain was first described earlier this year following a joint survey by the WHO and the U.S. Centers for Disease Control and Prevention.

Resistance to anti-TB drugs occurs primarily due to poorly managed TB care. Problems include incorrect drug prescribing practices, poor quality drugs or erratic drug supply, in addition to patient noncompliance.