This World Tuberculosis (TB) Day, (March 24) brought to us another opportunity to review TB responses. Drug susceptible TB is treatable, curable and, with proper program interventions, it is possible to believe in the theme of World TB Day: ‘I can stop TB’. However, can we say the same for drug-resistant TB?
Drug resistant TB has been recorded in the world at the highest levels ever, according to the World Health Organization (WHO) report – “Anti-Tuberculosis Drug Resistance in the World“, February 2008.
DOTS (Directly Observed Treatment/Therapy Short Course) is the internationally recommended TB control strategy that includes standardized case detection, treatment and patient support. It requires consistent drug supply and effective monitoring systems. According to WHO, drug resistant TB is a symptom of poor program performance. Therefore, if we hope to change the outcome, and decrease the proportion of drug resistant TB, the DOTS program needs to be adapted, as well as implemented. More of the same might only compound the TB drug resistance threat.
The African, South East Asian and Western pacific regions account for 83 per cent of total TB case notifications, according to the Global Tuberculosis Control report of WHO (March 2008). China, India and Indonesia are home to two-in-three of the world’s TB cases. The Africa region has the highest TB incidence rate. These countries are expanding coverage of its TB Program at record-breaking speed. In its shadow, drug resistance is also upping its pace. The proportion of resistance to at least one anti-TB drug (any resistance) was found to be as high as 56.3 per cent in Azerbaijan.
Multidrug-resistant TB (MDR-TB) is defined as TB with resistance to Isoniazid and Rifampicin, the two most powerful first line anti-TB drugs. MDR-TB patients have significantly poor outcomes than patients with drug susceptible TB. Global estimates indicate that 4.8 per cent of TB cases were of MDR-TB (i.e., about half a million were MDR-TB patients). Currently, treatment is available only to one out of ten MDR-TB patients and 90 per cent of MDR-TB patients cannot have access to treatment they need today. About 50 per cent of MDR-TB cases are in India and China because of their large population. In Africa, hard-hit by HIV, the proportion of TB drug-resistance is no less alarming. In former Soviet Union, almost half of all TB cases are resistant to at least one anti-TB drug and every fifth case of TB will be of MDR-TB.
Extensively Drug-Resistant TB (XDR-TB) is virtually untreatable and is likely to emerge where second-line anti-TB drugs are widely and inappropriately used. XDR-TB is more expensive and difficult to treat than MDR-TB and outcomes for patients are much worse with the mortality rates being very high. So far, 46 countries have reported XDR-TB, with UK reporting the first XDR-TB case last week.
Studies suggest that transmission of TB, especially the drug-resistant strains, is more likely to take place where people living with HIV (PLHIV) congregate. Healthcare settings, for example those for Antiretroviral (ARV) delivery, is one such place where improper infection control can put PLHIV at a risk of contracting TB. TB is the most common opportunistic infection and the leading cause of death for PLHIV. Improving infection control in healthcare settings is clearly vital, doable and potentially life saving.
In many countries, insufficient laboratory capacity to test drug-resistance is a serious impediment in scaling up TB Programs. Even the new WHO report on TB drug resistance had data only from six African countries because other countries had no laboratory capacity to provide data on anti-TB drug resistance. Developing laboratories which provide rapid diagnosis of anti-TB drug-resistance, particularly for PLHIV, is of utmost importance to help improve TB responses.
Hence, more and better TB drugs and diagnostics in the public sector are urgently needed. But we also need better strategies to make TB Control Programs work more effectively for the most vulnerable and hard to reach communities. This is essential for improving treatment adherence and, as a consequence, reducing drug resistance.
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