Tuberculosis – An Under-appreciated Disease

Abstract

Tuberculosis Worldwide Tuberculosis (TB, as usually abbreviated) is a major cause of morbidity and mortality in many countries, and a signifi cant public health problem worldwide. The World Health Organization (WHO) estimates that there are about 8.8 million new cases of TB and 1.6 million deaths from TB every year.1 Non-compliance with anti-TB drug treatment, or inappropriate treatment, or both, has led to one of the greatest challenge facing TB control programmes worldwide, i.e. drug-resistant tuberculosis. Drug-resistant TB is much more diffi cult and costly to treat than fully drug-susceptible TB. An estimated 490,000 cases of multi-drug resistant TB (MDR-TB), causing about 110,000 deaths, occur each year among both new and previously treated cases. These cases are resistant to rifampicin and isoniazid, the 2 most effective fi rst-line anti-TB drugs. The 2008 WHO Report on Anti-TB Drug Resistance stated that the world was experiencing the highest ever recorded rates of MDR-TB, with an average proportion among all TB cases of 5.3%. There were 14 geographic areas showing MDR-TB rates greater than 6% among new TB cases. These areas were mainly in countries of the former Soviet Union and in China. The highest rate of MDR-TB was reported in Baku City, the capital of Azerbaijan, where nearly a quarter of new TB cases were reported to be MDR-TB.2 The same 2008 WHO Report also indicated that cases of extensively drug-resistant TB (XDR-TB) have been reported in 45 countries, and emphasised that this phenomenon threatens to derail 10 years of progress in TB control. XDR-TB is TB that is resistant not just to rifampicin and isoniazid, but also to a fl uoroquinolone and to 1 of 3 injectable second-line anti-TB drugs (kanamycin, amikacin or capreomycin). XDR-TB is thus very diffi cult to treat, and the success rate of treatment is only 30% at best, in contrast to 50% to 70% for MDR-TB and over 95% success for pan-sensitive tuberculosis. Another major challenge has been the impact of the pandemic of human immunodefi ciency virus (HIV). HIV