TB Rates Fall, But Many Hurdles Remain

Oct 26, 2012 | Robyn Correll Carlyle | Research & Policy

The WHO published its annual Global Tuberculosis Report 2012 last week, providing a recap of the latest data and analysis regarding the tuberculosis epidemic.

The nearly 300-page document presents information drawn from 204 countries and territories where 99 percent of tuberculosis (TB) cases occur. In addition to some encouraging statistics, the report highlighted the many challenges that still plague the global public health community in its fight against TB.

The good news is that trends are reversing. The Millennium Development Goal (MDG) to reel back the TB epidemic has already been achieved short of its 2015 deadline. New cases fell 2.2 percent between 2010 and 2011, the mortality rate has dropped by 41 percent since 1990, and overall, the world looks like it will reach its goal of a 50 percent drop in the TB mortality rate by 2015.

For those with TB, access to treatment has expanded since the 1990s, and for the first time the WHO has been able to estimate the number of lives saved – 20 million between 1995 and 2011. Overall, treatment rates have remained high. Nearly nine out of 10 cases of pulmonary TB (the most infectious kind) were successfully treated.

Progress has been made for those with HIV and TB co-infection. Collaborative TB/HIV activities saved an estimated 1.3 million lives between 2005 and 2011. Sixty-nine percent of patients with both HIV and TB living in Africa were started on anti-retroviral therapy – a vast improvement from the mere 3 percent in 2004 when it was first recommended.

The numbers are encouraging. But then comes the bad news.

Treatment remains a difficult hurdle. Current standards require six months of treatment for non-drug-resistant TB and more than 20 months for multi-drug resistant tuberculosis (MDR-TB). With the length of time and adherence needed, it’s no surprise that successful treatment rates among those with MDR-TB remain low. Of the 107 countries that reported treatment outcomes, only 30 said they were able to treat 75 percent or higher of patients with MDR-TB. 

Drug resistance occurs when TB patients do not get their full course of treatment. If they miss doses, skip medicines or stop treatment early, the bacteria can morph to be more resistant to antibiotics, and drugs lose effectiveness. When this happens, infected patients with the now-resistant TB can pass the resistant bacteria on to other people, introducing strains into the population that are much harder to treat.

To try and prevent this from happening, many countries are implementing a WHO-recommended strategy known as DOTS, or directly observed treatment, short-course. The key component of this strategy involves health care providers supervising anti-TB treatment to ensure that the right drugs are taken at the right time and for the entire length of the treatment course.

Despite the successful implementation of the DOTS strategy around the world, drug resistance is becoming more common. The WHO estimates that 3.7 percent of new cases – and 20 percent of previously treated cases – are MDR. Eighty-four countries have reported cases of extensively drug-resistant TB (XDR-TB).

XDR-TB is a rare type of MDR-TB that is resistant not only to the two most potent anti-TB drugs (isoniazid and rifampin), but also to any antibiotic belonging to the fluoroquinolone subgroup and one or more of the available second-line drugs.

Because of the long duration and complexity of the treatment of MDR and XDR-TB, it can be more than 200 times costlier than standard treatment. Programs in countries with the highest burden, like Russia, India and China, are underfunded and cannot scale up to meet the demands necessary to diagnose and treat MDR-TB.

Indeed, funding gaps appear to be a crucial obstacle in addressing TB. According to the report, about $1 billion of international donor funds are needed each year to control and treat TB. An additional $1 billion is needed for TB/HIV interventions to provide testing and anti-retroviral therapy to those who are co-infected. And $2 billion per year is required to research and develop new, shorter treatment regimens and vaccines. Current funding is roughly half of what is needed.

“It is time to reexamine the current tuberculosis control approach,” The Lancet published in an editorial regarding the report. “The status quo is unacceptable.”

Current strategies use a control-based approach is too short-term, relying too heavily on treatment and cure, The Lancet published. Despite advances in reducing the number of new cases each year, the report noted that the decline is too small to see elimination during this century. More effort should be placed on developing new innovations, like a safe, affordable and effective vaccine.

Some relief may be on the horizon. A new treatment regimen that could be used to treat MDR-TB in a simpler way and shorter time frame has seen some success in clinical trials. And while there still is not an effective vaccine, the report stated that developments over the past decade could mean at least one new vaccine be licensed by 2020. 

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