WHO's TB strategy comes under fire
[NEW DELHI] The World Health Organisation's strategy against tuberculosis (TB) is out of date and seriously flawed, according to the president of one of the world's leading health campaigning organisations, Médecins Sans Frontières International (MSF).
Speaking at a meeting in New Delhi last week, Rowan Gillies said that the DOTS (Directly Observed Treatment, Short Course) strategy recommended by the WHO is hindered by a decades-old diagnostic tool of limited use, a vaccine of uncertain efficacy, a long treatment regimen, and the reluctance of pharmaceutical companies to invest in new drugs.
He also said that the strategy excludes a large number of patients as it is not designed to address the specific context of HIV and TB. Greater investment in research and development (R&D) on new diagnostic tools, drugs and vaccines should be the cornerstone of future control of the disease, which kills about two million people every year, he added.
The DOTS strategy against TB was introduced on a global scale in 1995. It is based on five principles: government commitment for TB control; case detection by microscopic examination of mucous from patients' lungs; a standardised six-to-eight-month treatment using a combination of drugs; regular and uninterrupted supply of drugs; and standardised monitoring and assessment of the treatment results.
Both the diagnostic tools and drugs used in the strategy are out of date, according to Gillies, who was addressing the WHO's Stop TB Partners Forum.
Microscopic examination of lung mucous to detect TB was developed in 1882, he said. The technique can detect only lung TB, and not the 20 per cent of cases that infect the spine, bones, brain or lymph glands. Furthermore, many HIV-positive people with TB show increasingly negative results as AIDS progresses. Studies in Africa suggest that the test works in only 35-38 per cent of HIV-positive patients.
Furthermore, Gillies said, most of the TB drugs used today were developed half a century ago. Drug companies are carrying out some TB-related R&D, but their commitment to this field is limited, as the market mainly consists of people with very little purchasing power.
DOTS can work in stable countries with low HIV prevalence, he said. But it is not effective in nations with high HIV prevalence or in conflict-prone countries with migrating people, such as Afghanistan, Angola and Sudan.
The two-day meeting that opened on World TB Day on 24 March highlighted the need to accelerate DOTS implementation in 22 high-burden countries, and tackle the growing problems of multi-drug resistance and co-infection with HIV.
Other speakers at the meeting echoed Gillies' concerns about the strategy. Douglas Young from Imperial College, London, for example, said that the current TB vaccine works only in children and offers limited protection in adults.
Laura Hakokongas, one of Gillies' colleagues, warned that several DOTS protocols and recommendations had not been substantiated in large-scale clinical trials and had little empirical basis. For example, she said, the dosage of the drugs ethambutol and isoniazid recommended in children is based on research on adults, and has never been studied in children.
Leopold Blanc, WHO's coordinator of TB strategy and operation, admitted that DOTS has flaws, such as excluding diagnosis based on X-rays or other methods, and relying on hospitals or government clinics for treatment.
Data from clinical trials in Africa and Pakistan indicate only a 70 per cent cure rate. "This is not acceptable," Blanc said. However he added that these trials were conducted in hospitals with no patient follow-up – an essential component of DOTS.
Blanc pointed out that field-based observations are reporting a higher success rate of between 80 and 90 per cent, adding "It is the best that we have so far."
Delegates at the meeting urged the medical and scientific community to harness science for faster and easier detection and cure for TB. They also expressed hope that two new candidate vaccines currently undergoing clinical trials, and drugs being tested for shortening the treatment duration, will help advance the fight against the disease.