- The major World Health Organization programme to curb
tuberculosis globally is failing to bring the disease under control, warns
a new review.
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- The WHO's strategy to combat the widespread infectious
disease involves stopping the spread of TB by treating people who have
tested positive for it. Because patients can fail to follow the long
courses
of treatment needed for TB, WHO launched its "directly observed
therapy,
short course" (DOTS) where patients receive treatment under
supervision.
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- This means they are more likely to complete treatment,
which prevents further spread of the disease, as well as the development
of antibiotic resistance.
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- But global TB rates continue to rise ñ and even
soar in countries riven with HIV/AIDS ñ warn Timothy Brewer and
Jody Heymann of Harvard University in Massachusetts, US. "After almost
10 years of a control strategy that has done little to reduce or to
eliminate
TB, global TB control needs to be reassessed," they say.
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- DOTS was launched after WHO declared TB a global
emergency
in 1993. At that time, one third of the world's population was believed
to be infected by the bug ñ although many people do not show
symptoms.
And 7.5 million new cases and 2.5 million deaths were caused by TB every
year.
-
- But Chris Dye, co-ordinator of the tuberculosis
monitoring
and evaluation team at the WHO, stresses that DOTS has produced drastic
cuts in TB rates in some regions. "In a very real sense DOTS is
working.
What these authors are saying, and we are agreeing, is that it's not
working
fast enough."
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- Latent TB
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- He says the paper does not acknowledge the improvements
seen with DOTS. "The bottom line is although DOTS has its defects,
it has to remain the foundation of TB control," he told New
Scientist.
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- "The point of the commentary is not to say 'we think
DOTS is bad' but we need to think about TB control in general ways,"
Brewer told New Scientist. He points out that HIV has been a
"tremendous
factor" in TB control over the last decade, as HIV patients are more
susceptible to TB, and that control strategies need to address this.
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- Dye says more than 10 million people worldwide have been
successfully treated over the last 10 years using DOTS. And in a recent
paper in The Lancet, DOTS was shown to cut TB prevalence by a third in
half of China ñ 500 million people ñ over a decade.
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- But the situation is complicated because many people
infected with Mycobacterium tuberculosis do not develop the disease
ñ
two billion people globally have "latent" TB. And over half the
people with TB do not test positive for the disease using a sputum smear
test.
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- The DOTS strategy relies upon identifying TB patients
using this test, and actively treating them. By concentrating on these
smear positive patients, DOTS and its sister strategy for drug-resistant
TB, called DOTS-Plus, are likely to have "only a modest impact"
on global TB control, say Brewer and Heymann. An estimated 9.1 million
people with TB worldwide test negative, note the pair, and they may be
responsible for 1.4 million new infections every year.
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- Large backlog
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- Brewer and Heymann also point out that the WHO strategy
is based on preventing people with the disease from spreading it, rather
than overall prevention. "The lack of historical precedents for this
approach is worrisome for the successful control and ultimate elimination
of TB with this strategy," they write.
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- They suggest treating people with latent TB with an
antibiotic,
called isoniazid, as one strategy. However, Dye points out that this
recommendation
is "theoretical, not practical" as it would involve persuading
people with no symptoms to take the antibiotic every day for nine months.
And with a third of the world infected there would be a "very large
backlog" to tackle.
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- But this could be attempted in the case of patients with
both HIV and latent TB, who are extremely vulnerable, he says.
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- Dye is realistic: "Nobody is thinking about
eradication
at the moment ñ that won't happen for another century. What will
happen is that TB is locally eliminated as a public health
problem."
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- Journal reference: Journal of Epidemiology and Community
Health (DOI: 10.1136/jech.2003.008664)
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- © Copyright Reed Business Information Ltd.
- http://www.newscientist.com/news/news.jsp?id=ns99996392
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