Catherine Sasman
23 September 2008
interview
The Novartis Institute for Tropical Diseases (NITD) held a global symposium in Mozambique last week, bringing together world-renowned tuberculosis experts to focus on critical issues facing TB treatment today, such as tackling resistant strains and treatment shortenings.
New Era spoke to NITD chairperson and Head of Corporate Research, Paul Herrling, about the discussion at the meeting.
TUBERCULOSIS (TB) particularly multi-drug resistant (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) - is becoming a global health issue.
In Namibia, the current case notification rate of TB is 15771 (from 2006 figures), which means that there are 765 cases per 100000 people. That also means that Namibia has the second highest TB case notification rate in the world after Swaziland.
There is a strong link between TB and HIV/AIDS. According to statistics of the Ministry of Health and Social Services, 60 to 70 percent of the 30 percent TB patients in the country have tested HIV/AIDS positive.
Worldwide, about one-third of the world's population is infected with the TB bacillus, and one person is being infected every second.
According to NITD, the MDR-TB problem is more widespread than previously thought, and is worsening.
"In some TB hot spots, at least 20 percent of all registered TB cases were due to MDR-TB, and often a high percentage of those meet the criteria for XDR-TB," the NITD said.
The organisation said the over 400000 cases of MDR-TB occurring yearly are as a result of under investment in basic TB control, poor management of anti-TB drugs and transmission of drug-resistant strains.
And 79 percent of those cases are 'super-strains' that are resistant to three of the four current treatments.
To combat this growing public health concern, researchers at NITD are applying new genomics and bioinformatics technologies to develop novel treatments for multi-drug resistant TB.
Indications are that the prevalence of tuberculosis (TB) is on the increase worldwide. What would you ascribe this to?
The spread of TB has been linked to urban crowding, inadequate diagnostic and treatment infrastructure, globalisation and world travel. Left untreated, each person with active TB will affect on average about 10 to 15 people annually.
What countries are most affected and what are the contributing factors?
TB is endemic to South-east Asia, sub-Saharan Africa and Eastern Europe, but is spreading. MDR-TB is also on the rise in Eastern Europe and Central Asia, where patients are 10 times more likely to develop a drug-resistant strain of TB, often due to inadequate treatment.
Because TB treatments are sometimes unsupervised, patients often discontinue their own treatment cycles due to the high cost of medication and the discomfort it causes.
Other factors contributing to patients' difficulty adhering to treatment regimes include the length of time each treatment takes and a lack of adequate drug supply to the poorest, most vulnerable populations.
Can you briefly describe the difficulties experienced with the treatment of TB?
TB therapy may be effective but is also problematic. Not only does the treatment last between six months and two years, but the drugs also cause nasty side effects such as sickness and vomiting, rashes and flu-like symptoms.
Because many patients feel better in the first weeks after starting therapy, they stop taking their medicines. This is a big issue in TB control.
By stopping treatment, patients are unknowingly putting their lives at risk as TB bacilli are still living in their lungs, potentially causing resistance to further doses of anti-TB drugs.
The result is a particularly dangerous form of bacterium, the multi-drug resistant TB (MDR-TB). Already, strains have been found which resist the two most powerful anti-TB drugs.
MDR-TB can be cured but it is difficult to treat. The drugs are also 100 times more expensive than drug-susceptible TB and more toxic.
Can you explain the 'super-strains' of TB and how they impact on the treatment of TB?
Two particularly dangerous forms of the disease are known as multi-drug resistant TB and extensively drug-resistant TB.
MDR-TB is defined as the disease caused by TB bacilli resistant to at least isoniazid and rifampicin, two antibiotics that are key components of the commonly used treatment regimen.
According to a WHO [World Health Organisation] estimate, about 50 million people worldwide are infected with MDR-TB, and at least 300000 new cases of MDR-TB occur annually worldwide. And estimated 500000 cases of MDR-TB occurred in 2007 alone. Some 79 percent of those cases are 'super-strains' that are resistant to three of the four current treatments.
Extensively drug-resistant tuberculosis is a relatively rare type of multi-drug resistant TB. It is resistant to almost all drugs used to treat TB, including the two best first-line drugs: isoniazid and rifampicin.
XDR-TB is also resistant to the best second-line medications:
fluoroquinolones and at least one of three injectable drugs (that is amikacin, kanamycin, or capreomycin).
XDR-TB is most frequent in the countries of the former Soviet Union and in Asia, but has been identified in all regions of the world.
For example, four percent of MDR-TB cases in the United States met the criteria of XDR-TB.
What is Novartis' commitment to fighting TB and what constitutes the TB Alliance?
A long-term commitment to helping reduce the global disease burden is part of Novartis' corporate citizen efforts to improve the access to medicines in the developing world.
Since the NITD's establishment in 2002, its core strategy has been to collaborate with other organisations to develop and deliver life-saving treatments for those who need them. In an effort to halt the rise and spread of tuberculosis, the NITD and the Global Alliance for TB Drug Development (TB Alliance) recently announced a five-year research collaboration designed to yield new medicines for TB, including drug-resistant strains.
Under the collaboration, the NITD and the TB Alliance will share information on new and ongoing TB drug discovery projects with the goal of developing novel anti-biotic compounds to treat the disease.
Has the symposium reached any conclusions on the fight against TB?
Health leaders at the conference agreed upon the need to combat multi-drug resistant strains and extensively-drug resistant strains of TB, the need for new therapies and target acceleration, and the need for shorter, more effective treatments.
Scientists convened at the conference to discuss findings on drug-resistant TB in an effort to gather new knowledge, better understand the disease, and formulate new ideas for fighting drug resistant strains.
Ways to reduce treatment time were also discussed as the longevity of treatment poses great challenges to local African patients who already face infrastructural and healthcare hurdles.
Treatments are generally six months, and even reducing them by half would be a great achievement.
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