From washingtonpost.com

About one in every 20 new cases of tuberculosis worldwide is now resistant to two or more drugs, and in some regions of the former Soviet Union the proportion is closer to one in every five cases, the World Health Organization reported yesterday.

In addition, “extensively drug-resistant” tuberculosis (XDR-TB), a relatively new subtype of the disease that takes $15,000 in drugs and two years to treat, has now been found in 45 countries. TB epidemiologists estimate 40,000 new cases emerge each year, and the death rate in untreated or poorly treated cases is close to 100 percent.

“Multi-drug-resistant” tuberculosis (MDR-TB) could account for 22 percent of all cases in Baku, Azerbaijan, and 19 percent of Moldova’s, a rate that “was not thought to be possible” in the 1990s, said Mario Raviglione, the head of WHO’s tuberculosis department, who will discuss the data today at a congressional hearing.

“The speculation was that it wouldn’t go over 10 percent,” he said. The assumption was that the drug-resistant strains would be seen almost exclusively in AIDS patients and other people with weakened immune systems, but it is now clear that once MDR bacteria emerge — almost always because of inadequate or improper treatment — they can circulate easily in the general population.

“The Azerbaijan data just blew me away,” said Richard E. Chaisson, director of the Johns Hopkins Center for Tuberculosis Research.

Normally, tuberculosis is treated with four drugs for at least six months. MDR strains are resistant to the two most commonly used medications, rifampin and isoniazid. XDR-TB is resistant to those two and at least two others.

The new data were compiled from national, regional and city surveys. Because the list of countries surveyed differs that in from previous reports, it is impossible to say whether the estimate that 4.8 percent of all TB cases are MDR or XDR is an increase or decrease from a few years ago.

“What is fair to say is that what we are seeing globally now is different from what we were seeing a decade, or a decade and a half, ago,” Chaisson said.

Around the world, there are about 9 million new tuberculosis cases each year and about 1.6 million deaths from it (out of 62 million deaths from all causes). The disease, which usually attacks the lungs, is second only to AIDS in deaths caused by infectious illness.

MDR strains accounted for more than 6 percent of new TB cases in 14 regions. The areas included the former Soviet republic of Georgia and two regions of China (7 percent); Armenia (9 percent); Latvia (11 percent); Tashkent, Uzbekistan (15 percent); and the Donetsk region of Ukraine (16 percent).

In both Latvia and Ukraine, many people with MDR tuberculosis were also infected with HIV, usually contracted through intravenous drug use. Some experts believe drug-resistant strains are more likely to attack people who have AIDS, although the more probable cause is that HIV-infected people share the same close environment and are passing the dominant TB strain there to each other.

Mortality rates from treated XDR-TB are not known, because places where treatment is available do not have large numbers of cases. In Latvia, however, where many people have been treated, the cure rate is about 30 percent.

While the percentage of drug-resistant tuberculosis cases in Baltic countries is stable, the total number of TB cases is now half of what it was in the mid-1990s. In Russia, however, both the amount of TB and the percentage that is drug resistant is climbing.

Tuberculosis that responds to drug treatment can be cured for about $20, while the medications needed for MDR and XDR infections can cost $1,500 to $15,000 on the world market. Countries can buy the drugs through WHO for as little as $1,000 if they can demonstrate the need and ensure proper usage.

WHO estimates that about $4.8 billion will be needed for overall TB control in low- and middle-income countries this year — about $2.5 billion more than is available now.

“My frustration is to see this thing growing and to call for emergency relief for these countries and yet to see no special response to this tragedy of TB,” WHO’s Raviglione said.

This entry was posted on Monday, March 24th, 2008 at 3:21 am and is filed under Drugs & Prescriptions. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.