Drug-resistant TB spreading around the world
Pastor Dale Morgan
Drug-resistant TB spreading around the world*
Source: WHO; CDC
By Anita Manning, USA TODAY
A dangerous form of tuberculosis that resists treatment with both
first-line and second-line drugs is spreading around the world, spurring
an urgent search for new ways to stop the ancient scourge.
Extensively drug-resistant TB (XDR-TB) has been found in 28 countries,
including, rarely, the USA, the World Health Organization says.
Multi-drug-resistant TB (MDR-TB), which is immune to the two most
powerful anti-TB drugs, has been reported for years and is now in 90
countries. But it was not until March 2006 that WHO and the Centers for
Disease Control and Prevention recognized XDR-TB, a form of the disease
that has developed further immunity, which makes some of the second-tier
drugs ineffective. It is still sometimes curable, but only with
expensive drugs and intensive treatment.
Last August, an outbreak in South Africa was reported in which 52 of 53
patients with XDR-TB died. Most also had HIV. Now, XDR-TB is in every
province of South Africa. At last week's Conference on Retroviruses and
Opportunistic Infections in Los Angeles, Karin Weyer of the South Africa
Medical Research Council estimated 600 XDR-TB cases in the country with
a fatality rate of 84%. More than 80% of those infected are HIV patients.
WHO says $650 million is needed each year to control drug-resistant TB.
"We were fairly complacent with the sense that we had drugs that work,
and we do," says Maria Freire, CEO of The Global Alliance for TB Drug
Development, a non-profit devoted to finding new TB drugs.
But when those drugs are given inappropriately or stopped too soon, drug
resistance emerges, requiring more expensive and toxic alternatives.
Regular TB can be cured with a combination of drugs taken for six
months. MDR-TB requires a different combination, taken for 18 months to
two years. If that regimen isn't followed carefully, XDR-TB can emerge.
"It doesn't mean you're totally untreatable, it means … they're giving
you everything they have," Freire says. And in some cases, "we've simply
run out of ammunition. We no longer have the drugs we need to fight this."
The TB Alliance is working with pharmaceutical companies, academic
researchers and institutes to find new drugs, Freire says, and there are
promising candidates in the pipeline. She says the goal is to develop
drug combinations that attack different parts of TB bacteria to reduce
resistance; that can be taken along with the anti-retroviral therapy
needed by HIV/AIDS patients; and that are effective when taken for two
months or less.
"That's a huge leap," she says, "but not an impossible goal."
Ultimately, she says, the hope is to be able to "treat TB as you would
any normal infection, with a 10-day treatment," but that may require a
decade or more of biological research.
GLOBAL TUBERCULOSIS (2005 ESTIMATES)
• All forms of TB: 8.8 million (deaths: 1.6 million)
• Multi-drug-resistant TB (MDR-TB): 424,000 (deaths: 116,000)
• Extensively drug-resistant TB (XDR-TB): 27,000 (deaths: 16,000)
• XDR-TB in the U.S.: A 47 cases since 1993