Today is World TB Day. Although there is much to celebrate, with 49 million lives being saved through the diagnosis and treatment of tuberculosis (TB) between 2000 and 2015, the rise in TB-causing bacteria that are resistant to key treatments now threatens to derail decades of progress in controlling TB.
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AFB stain showing Micro bacterium tuberculosis (TB).
TB characteristically affects the lung causing persistent coughing and breathing difficulties. It is caused by the bacteria Mycobacterium tuberculosis and is easily transmitted from person to person through the air. TB kills more people each year than any other infectious disease; it was responsible for the deaths of around 1.8 million people in 2015. The majority of cases occur in Asia, which had 61% of the new TB cases reported in 2015. High levels of worldwide travel, however, make this a global threat.
The disease is curable and preventable. Indeed, improved diagnosis and treatment of TB has reduced its incidence by an average of 1.5% per year since 2000. It was hoped that the disease could be eradicated by 2030, but a report published today in Lancet Respiratory Medicine warns that efforts could be severely hindered by the rise in multidrug-resistant and extensively drug-resistant TB bacteria.
Resistance to at least one major anti-TB drug is now found in one in five TB cases, and resistance to two or more essential first-line TB drugs occurs in one in every twenty cases. It was estimated that in 2015, 480,000 TB cases were multidrug-resistant. Mortality rates are high with drug-resistant TB (40‑60%) and health workers caring for infected patients are themselves at risk. Resistant TB also represents a huge financial burden. In 2014, a third of the budget allocated to fighting the global TB epidemic was used in the treatment of drug resistant TB (despite these cases representing only 5% of the total caseload).
New antibiotics that are effective against TB resistant to standard therapies have been developed. It is important that these treatments are used carefully and effectively to avoid TB bacteria acquiring resistance to these too.
Lead author of the report, Professor Keertan Dheda of the University of Cape Town explained “Resistance to anti-tuberculosis drugs is a global problem that threatens to derail efforts to eradicate the disease. Even when the drugs work, TB is difficult to cure and requires months of treatment with a cocktail of drugs. When resistance occurs, the treatment can take years and the drugs used have unpleasant and sometimes serious side effects".
The urgent priority is to ensure rapid and accurate diagnosis of TB and adherence to clear treatment guidelines. Once this is achieved, the risk of drug resistance developing is reduced and the effectiveness of new treatments will be maintained. This is essential for the success of global efforts to control TB.
Sources
The Lancet Respiratory Medicine Commission. The epidemiology, pathogenesis, transmission, diagnosis, and management of multidrug-resistant, extensively drug-resistant, and incurable tuberculosis. Lancet Respir Med 2017. Epub ahead of print 24 March 2017. Available at http://www.thelancet.com/journals/lanres/article/PIIS2213-2600(17)30079-6/fulltext?elsca1=tlpr
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