A dangerous form of drug-resistant tuberculosis has reached its highest levels ever, accounting for at least 5 percent of all new TB cases worldwide and 15 percent to 22 percent of new cases in parts of the former Soviet Union and China, the World Health Organization said Tuesday.
The WHO report, the first new survey of TB incidence in four years, estimated that there are nearly 500,000 new cases of multidrug-resistant TB, commonly known as MDR-TB – about 5 percent of the 9 million total cases of TB each year.
The highest rate was recorded in Baku, Azerbaijan, where 22.3 percent of all new cases were MDR. Rates of 14.8 percent or higher were also found in Moldova, the Donetsk province of Ukraine, the Tomsk province of the Russian Federation and in Tashkent in Uzbekistan.
MDR-TB also was found in a high proportion of cases in China’s inner Mongolia and Heilongjiang regions.
In contrast, the highest rate reported in the 2004 survey was 14.2 percent in Kazakhstan.
Experts attributed the high incidence in those regions to poverty, congestion, alcoholism and stress from the dismantling of the Soviet Union.
Surprisingly low rates of drug-resistant strains were found throughout most of southern Africa, which has the highest rates of TB in the world.
Dr. Mario Raviglione, director of the WHO’s Stop TB department, 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.
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.
The MDR variety of the disease is resistant to two first-line antibiotics, isoniazid and rifampicin. Treatment can take as long as two years, compared with six months for conventional TB. The drugs used are more toxic and 100 times more expensive.
An even more serious form, known as extensively drug-resistant TB, commonly called XDR-TB, is resistant to both of those antibiotics and to fluoroquinolones and any of the injectable antibiotics, such as kanamycin or capreomycin. Treatment may require surgical removal of part of the lungs and some strains are virtually untreatable.
The WHO survey found that XDR-TB has now been detected in 45 countries.