Drug resistant tuberculosis can be controlled, says WHO
The World Health Organization (WHO) has for the first time assembled
hard evidence that the emergence of drug resistant tuberculosis
can be held back by properly controlled treatment programmes.
It warns, however, that the "window of opportunity" to prevent
the spread of drug resistant strains will be missed if urgent action
is not taken to persuade more health authorities and doctors to
use its recommended treatment strategy, which still reaches only
1 in 5 patients with tuberculosis worldwide.
Drug resistance is significant
only in countries without good control programmes
The warning comes in a global report released this week on World
Tuberculosis Day at a ministerial summit in Amsterdam. It shows
a disturbingly high prevalence of drug resistant strains of Mycobacterium
tuberculosis in parts of eastern Europe and Asia.
By contrast, countries that have used the recommended treatment
strategy tend to have very low rates of resistance. "We only see
significant drug resistance in countries without good control programmes,"
said Dr Marcos Espinal, an epidemiologist and head of the report's
team of authors.
The WHO has been arguing for directly observed treatment, short
course ("DOTS") for years on the basis of small scale studies that
show it helps to prevent the emergence of resistance.
But this report is the first that allows it to show a clear inverse
relation between the numbers of patients receiving DOTS and the
prevalence of resistant strains in a widespread sample of populations.
"This conclusion is a 'no brainer' to those of us who have been
involved in DOTS, but now we have the evidence," said a WHO spokesman.
The new report has data from 58 countries and other settings (such
as provinces of China) and enough data to detect trends in 28. Its
authors warn, however, that the picture is still incomplete. The
scale of drug resistance is not fully known in the five countries
with the highest incidence of tuberculosis worldwide: India, China,
Indonesia, Bangladesh, and Pakistan.
As before, a high rate of resistance to one or more drugs was found
in new tuberculosis cases in Estonia, with 37% of all strains resistant
to any drug and 14% multidrug resistant. The prevalence of resistance
in Estonia had grown substantially since the last survey, both in
new cases and previously treated cases.
Other countries and settings with worrying rates of drug resistance
included Latvia; two Russian "oblasts" (territories); Iran; the
Henan and Zhejiang provinces of China; and Tamil Nadu state in India.
Germany and Denmark have both seen increases in drug resistance,
but the scale of the problem is small.
In the parts of eastern Europe where rates of resistance are high,
a tradition of treating patients for lengthy periods in hospital
has encouraged resistant strains to flourish.
Phyllida Brown, London,
Anti-tuberculosis Drug Resistance in the World is available from the Publications Department, World Health Organisation 1211 Geneva 27, Switzerland.
studentBMJ 2000;08:131-174 May ISSN 0966-6494
