New TB strains increasingly impervious to some or all available drugs

Marlowe Hood

Marlowe Hood

PARIS - In the time it takes you to read this sentence out loud, someone somewhere in the world will have died of an illness that has been readily curable for half a century.

That relentless tally will rise to 1,6million people over the course of a year, making tuberculosis the deadliest infectious disease on the planet after Aids and ahead of malaria, according to the World Health Organisation (WHO).

Today the WHO will release a major report on TB, two days ahead of World TB Day, with a special focus on 22 "high burden countries", eight of which are in Africa.

There will be some good news.

The worldwide epidemic of TB seems to have peaked; new, more effective drugs are in the pipeline; and many countries have met 10-year targets for detection and treatment.

India and China in particular, experts say, have made measurable strides in curbing infection and reducing mortality.

But progress in checking the disease's spread is severely threatened, health officials add, by new strains impervious to some or all of the arsenal of drugs currently available.

Another peril is the HIV-Aids epidemic, which weakens the human immune system, creating a hospitable environment for what was once aptly called the "wasting disease" or "consumption".

The number of countries in which so-called extensively drug-resistant TB - XDR-TB for short - has surfaced nearly doubled from 19 to 35 in only a year, including newly reported outbreaks in South Africa and 10 nations in Europe.

"The level of resistance in XDR-TB seriously reduces treatment options, resulting in high rates of treatment failure and consequent mortality," Paul Nunn of the WHO's TB and HIV and drug-resistance programme said recently.

If the problem is not tackled now, he warned, the world will witness "the replacement of the current global epidemic of mostly drug-susceptible TB with multidrug-resistant or XDR disease, and the need to solve a human catastrophe at vastly greater expense".

Though the numbers remain paltry compared with the incidence of TB as a whole, of the 27000 confirmed cases of XDR-TB reported in 2005, 16000 - 60percent - proved fatal.

Of the 420000 cases of the somewhat less virulent multidrug-resistant TB (MDR-TB), almost one in four died.

Overall, there are eight million to nine million new cases of TB, all types combined, every year.

Current treatment for TB, developed more than 40 years ago, is difficult to administer and requires six to nine months of therapy.

When patients fail to complete a treatment, the germ Mycobacterium TB, which causes the disease, develops a resistance to the drugs to which it has been exposed.

With an estimated two billion people carrying a latent form of the infection - one out of every three people on the planet - the risk of exposing vulnerable populations to highly pathogenic forms of a disease that spreads through the air, as with the common cold, has sounded the alarm among health professionals.

"The fact that there are essentially untreatable forms of TB in the community is very worrisome," said Richard Chaisson, a professor at John Hopkins University in Baltimore and a leading authority on XDR-TB.

"Urgent measures are needed."

Posing an additional challenge is the overlay of TB and HIV-Aids, especially in sub-Saharan Africa.

"Africa has the highest rates in the world of HIV-Aids infection, and those rates have fuelled the TB resurgence. People who have compromised immune systems are much more vulnerable," said Melvin Spigelman, head of research and development at the New York-based TB Alliance, which leads the world in developing new drugs to fight the disease.

Nearly 200000 people living with HIV died of TB in 2005 alone, he said.

Curing patients who have both diseases is hampered by the incompatibility of drugs considered essential for each illness, giving rise to a highly dangerous condition known as IRIS - immune-reconstitution inflammatory syndrome. - Sapa-AFP