Global alert over deadly new TB strains
Pastor Dale Morgan
Global alert over deadly new TB strains*
· Disease untreatable with currently available drugs
· South African cases raise fears for Aids programme
Sarah Boseley, health editor
Wednesday September 6, 2006
The Guardian
World health officials last night put out an unprecedented warning that
deadly new strains of tuberculosis, virtually untreatable using the
drugs currently available, appear to be spreading across the globe.
The new strains are known as extreme drug-resistant TB, or XDR-TB. They
have been identified and have killed people in several countries,
including the United States and eastern Europe, and they have recently
been found in Africa, where they could swiftly put an end to all hope of
containing the Aids pandemic through treatment.
Yesterday Paul Nunn, who heads the World Health Organisation's TB
resistance team, said the situation was very serious. There are 9m cases
of TB in the world and the WHO estimates that 2% of them - or 180,000 -
could be XDR-TB.
"This is raising the spectre of something that we have been worried
might happen for a decade - the possibility of virtually untreatable
TB," said Dr Nunn.
Even in the United States, which has the best medicines available, a
third of those who have been diagnosed with XDR-TB have died. In March,
the Centres for Disease Control in the US registered that there had been
64 cases of XDR-TB; 21 of those ended in death.
Significant numbers of cases have been confirmed in Latvia and Russia,
but in many parts of the world, XDR-TB could be rife but unrecognised.
One of the reasons the WHO is concerned is that tuberculosis spreads
easily in confined places, such as aircraft. Multi-drug resistant TB
strains - those that are resistant to the two basic, first-line drugs
used to treat the disease - have spread everywhere, including to the UK.
Multi-drug resistant TB is increasingly common and is difficult and
expensive to treat. The patient must be given four out of the six
existing second-line drugs.
But the XDR-TB strains now appearing are a medical nightmare because at
least three out of those six second-line drugs have no effect. There are
no third-line drugs.
The spectre of a new untreatable plague has concentrated minds because
of the identification of a cluster of cases in KwaZulu Natal, in South
Africa. Scientists ran tests on people with tuberculosis in a rural part
of the region. They studied 544 patients and found that 221 had TB
strains against which the two common drugs, rifampicin and isoniazid,
had no effect.
Finding such a high rate of multi-drug resistant TB was serious enough.
But they also discovered that 53 of the patients had XDR-TB - and 52 of
them died within an average of 25 days.
All the XDR-TB patients who could be tested were found to be HIV
positive. Anybody with the virus becomes very susceptible to all types
of infection. Tuberculosis is a major killer of people with Aids.
But the swift deaths of all but one of the study group in KwaZulu Natal
has huge implications for the antiretroviral (ARV) drug treatment
programme being rolled out across Africa in the hope of keeping millions
of people with HIV alive and well, pending a cure.
"There is no point in investing hugely in ARV programmes if patients are
going to die a few weeks later from extreme drug-resistant
tuberculosis," said Dr Nunn.
The XDR-TB cases in South Africa were discovered only because Harvard
scientists embarked on a study to gauge the extent of drug resistance.
In other parts of Africa, there are no researchers or facilities to make
the diagnosis, let alone monitor the numbers. "In most of the countries
to the north of South Africa, they wouldn't be able to tell you what is
going on," said Dr Nunn.
Most African countries either do not have a national reference
laboratory for TB or they do not have enough. Kenya has one, he said; it
should have four or five.
Tomorrow, WHO officials and international TB experts will take part in
an emergency two-day meeting in Johannesburg, South Africa, to decide
what action must be taken to address the crisis. They are expected to
make recommendations that will include the importance of ensuring all TB
patients take their full six-month course of drugs, to try to prevent
resistance developing. In much of the world, that has proved difficult.
Tuberculosis drugs are old drugs. The white death or consumption, as TB
used to be known, was thought to have been conquered more than 50 years
ago. Drug companies have not invested in tuberculosis because it has
been considered a disease of impoverished developing countries.
More recently, as the Aids pandemic has alerted the world to the
inadequacies of medical treatment for a number of diseases in Africa,
public-private partnerships have been been set up to attempt to find and
develop new drugs, but there are none on the horizon yet.
Explainer: Tuberculosis
TB's origins can be traced back to antiquity, from the spinal cord
fragments of Egyptian mummies to the writings of Hippocrates who
identified phthisis, the Greek term for consumption, as the most
widespread disease of the period.
Its symptoms - red swollen eyes, pale skin, coughing blood - led to it
being labelled as vampirism during the Industrial Revolution. It was
identified as a disease in the 1820s but was not named tuberculosis
until 1839. Robert Koch's discovery of the microbe responsible,
Mycobacterium tuberculosis, in 1882, earned him the Nobel prize in medicine.
In the early 19th century TB was rampant, responsible for up to one in
four of all deaths in England. It spread through tiny particles released
when an infected patient coughed or sneezed. Public health improvements
cut the number of cases in the early 20th century, but not until the
discovery of the antibiotic streptomycin in 1946 was the disease treatable.
Hopes of eradicating TB faded when drug-resistant strains emerged in the
1980s, followed by strains resistant to multiple drugs.