One in 10 cases of tuberculosis in China cannot be treated by the most commonly-used drugs, driven by a lack of testing and misuse of medicine, according to a national survey that showed for the first time the size of the drug-resistant epidemic.
Researchers say the findings from the 2007 survey on drug-resistant TB, published Thursday in the New England Journal of Medicine, show that the government must invest more in public health services to better diagnose drug-resistant strains of the killer lung disease. Hospitals must also be prevented from routinely misusing drugs that worsen the problem, they say.
"For the first time, we have a representative, national survey of this problem in China. It shows that this is pretty serious," said Dr. Daniel Chin, a TB expert at the Bill & Melinda Gates Foundation in Beijing who is one of the study's authors. "One in 10, by any standard globally, would be pretty high."
The proportion of drug-resistant TB found in the survey was in line with previous estimates that were based on provincial studies, the researchers said. While the survey was done in 2007, the researchers said it took time to culture and test samples from each patient.
The ancient and treatable lung disease is caused by germs that spread when a person with active TB coughs, sneezes or speaks. It has in recent years evolved into stronger forms: drug-resistant TB, which does not respond to two top drugs, and extensively drug-resistant TB, which is virtually untreatable. A handful of what's been unofficially dubbed `totally drug-resistant' cases have also been identified, most recently in India.
TB is usually cured in six to nine months with a mixture of four antibiotics, but if that treatment is interrupted or the dose reduced, the bacteria mutate into a tougher strain that can no longer be killed by standard drugs. The drug-resistant form takes up to two years and thousands of dollars to treat.
The survey conducted by the Chinese Center for Disease Control and Prevention, or China CDC, also showed that 8 percent of patients with drug-resistant TB were actually extensively drug-resistant cases. The survey's researchers tested 4,000 TB patients recruited through local TB clinics over nine months.
In 2007, an estimated 110,000 cases of drug-resistant TB and 8,200 extensively drug-resistant cases developed, making it the largest annual number of new drug-resistant cases in the world, the study said.
"This is a very grave situation because we don't have any new drugs to treat the patients with," said Dr. Wang Yu, director of the China CDC and another author of the study. "It is a problem that the whole world is facing... and over time, it will only increase."
The urgent need for new TB treatments has prompted drugmakers to open their research vaults and labs to scientists, and a number of new candidates are being developed.
In the past decade, China made marked progress in fighting tuberculosis, which until recent years was the most fatal infectious disease. But many state-run TB facilities still don't have the resources to test patients for drug-resistant strains in order to give them the right drugs, and many are also unable to track every patient to ensure that drug regimens are closely followed.
The survey also showed that patients who were last treated in a tuberculosis hospital were 13 times as likely to have drug-resistant TB as those who had been treated elsewhere. They likely became infected in the hospitals or were given the wrong drugs. The overuse and misuse of antibiotics is very common in China because it is a way for underfunded hospitals to boost revenue through drug sales.
"The hospital is clearly a major culprit in this, even what we call tuberculosis hospitals which are supposed to be specialized in the treatment of drug-resistant TB, they are actually perhaps, as this study has implicated, contributing to drug-resistant TB," said Chin, who is also deputy director of programs at the Gates Foundation in China.
China's rate of drug-resistant TB cases is lower than in some Eastern European countries, but the absolute number of cases, given the country's large population, is high - similar to that of India, said Dr. Fabio Scano, World Health Organization's Stop TB officer in Beijing, who was not involved in the study.