Questions About Drug- and multidrug-resistant tuberculosis (MDR-TB)

Drug- and multidrug-resistant tuberculosis (MDR-TB) - Frequently asked questions

(Source: http://www.who.int/tb/challenges/mdr/faqs/en/index.html)

How does drug-susceptible TB become drug-resistant TB?
Drug resistance arises due to the improper use of antibiotics in chemotherapy of drug-susceptible TB patients. This improper use is a result of a number of actions, including administration of improper treatment regimens by health care workers and failure to ensure that patients complete the whole course of treatment. Essentially, drug-resistance arises in areas with poor TB control programmes.

What is multidrug-resistant tuberculosis (MDR-TB)?
MDR-TB is a specific form of drug-resistant TB due to a bacillus resistant to at least isoniazid and rifampicin, the two most powerful anti-TB drugs.

What is the difference between the management of drug-resistant TB and drug-susceptible TB?
In areas of minimal or no MDR-TB, DOTS achieves cure rates of up to 95%; rates high enough to dramatically reduce the TB burden while preventing the emergence of drug-resistant TB. However, an effective strategy, the management of drug-resistant TB is still in pilot stage. While drug-susceptible TB can be cured within six months, forms of drug-resistant TB (such as MDR-TB) require extensive chemotherapy (with drugs which have more side effects) for up to two years.

How do we measure drug-resistant TB globally?
In 1994, WHO, the International Union Against TB and Lung Disease, and other partners began the Global Project on Drug Resistance Surveillance in order to standardize the sampling and laboratory methodologies used to measure drug resistant tuberculosis. Today, areas representing almost half of global TB cases have been surveyed.

Are TB and drug-resistant TB real threats to everyone?
Presently, TB is the second greatest contributor among infectious diseases to adult mortality causing approximately 1.7 million deaths a year worldwide. WHO estimates that one-third of the world's population is infected with Mycobacterium tuberculosis. The WHO/IUATLD Global Project on Drug Resistance Surveillance has found MDR-TB (prevalence > 4% among new TB cases) in Eastern Europe, Latin America, Africa, and Asia.

Given the increasing trend toward globalisation, trans-national migration, and tourism, all countries are potential targets for outbreaks of MDR-TB.

How is WHO addressing the problem of drug resistance?

In 1998 WHO and several partners around the world conceived a strategy for the management of MDR-TB. The approach to the management of MDR-TB is under continuous development and testing. The latest recommendations on the management of drug-resistant TB are published in the Emergency Update of the WHO Guidelines for the programmatic management of drug-resistant TB. A working group on MDR-TB of the STOP TB Partnership was established in 1999 to assist in producing policy recommendations for Member States on the management of MDR-TB, based on the assessment of the feasibility, effectiveness and cost-effectiveness data generated by pilot projects implemented by the agencies/institutions participating in the Working Group, or by the World Health Organization (WHO); to coordinate and monitor the implementation of internationally comparable pilot projects for the management of MDR-TB; to establish a system that allows WHO Member States to have access to high-quality second-line drugs at reduced prices and, at the same time, prevents misuse of such drugs; to review progress achieved in countries managing MDR-TB through the Green Light Committee (GLC); and to identify resources to fund and implement MDR-TB control and to assist with global coordination of the initiative.

What is Extensively drug-resistant tuberculosis (XDR-TB)

What is Extensively drug-resistant tuberculosis (XDR-TB)

(Source: http://www.who.int/tb/challenges/xdr/en/index.html)

XDR-TB is the abbreviation for extensively drug-resistant tuberculosis (TB). One in three people in the world is infected with dormant TB germs (i.e. TB bacteria). Only when the bacteria become active do people become ill with TB. Bacteria become active as a result of anything that can reduce the person’s immunity, such as HIV, advancing age, or some medical conditions. TB can usually be treated with a course of four standard, or first-line, anti-TB drugs. If these drugs are misused or mismanaged, multidrug-resistant TB (MDR-TB) can develop. MDR-TB takes longer to treat with second-line drugs, which are more expensive and have more side-effects. XDR-TB can develop when these second-line drugs are also misused or mismanaged and therefore also become ineffective. Because XDR-TB is resistant to first- and second-line drugs, treatment options are seriously limited. It is therefore vital that TB control is managed properly.

Adv