TB increasingly resistant to some drugs

WASHINGTON — 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 (WHO) reported Tuesday.

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 in 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.

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

Experts attributed the high incidence in the former Soviet Union to poverty, congestion and alcoholism.

Surprisingly low rates of drug-resistant strains were found throughout most of southern Africa, which has the highest rates of TB in the world — although many countries were unable to report data because of the lack of sophisticated testing.

Raviglione attributed the low incidence to the overall lack of treatment in the region. If the majority of people are not getting antibiotics, he said, the TB bacteria will not develop resistance to them.

"But with the more widespread use of rifampicin and other drugs (in recent years), the situation is going to go more quickly out of control because of the presence of HIV," which leaves victims much more susceptible to TB, he said.

Tuberculosis is an infection of the lungs characterized by fever, weight loss, night sweats and coughing up of blood. The disease is spread primarily through microscopic droplets released when an infected person coughs, sneezes or speaks.

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