Using data on outcomes and impacts of tuberculosis across four countries with some of the highest rates of the disease, researchers from the U.S. Centers for Disease Control and Prevention have found indications that person-to-person transmission will drive rising rates of TB that does not respond to treatments of first and second resort over the next two decades.
Their study, published Tuesday in The Lancet online, produced estimates that almost a third of tuberculosis cases in Russia will be resistant to at least two common treatments by 2040, compared to almost a quarter of cases in 2000. Over that period, researchers found, the percentage of drug resistant tuberculosis cases would climb from nearly 8 percent in 2000 to 12.4 percent in India, from 6 percent to nearly 9 percent in the Philippines, and more than double, from 2.5 percent to 5.7 percent in South Africa. Researchers estimate that nearly one in 10 of those cases will be extensively drug-resistant, not responding to broad spectrum antibiotics and injectable drugs used in second-line treatment regimens.
The four countries together are home to nearly 40 percent of all cases of multidrug-resistant tuberculosis, a disease that kills an estimated 40 percent of diagnosed patients, and about 60 percent of those sick with extensively drug-resistant disease, the researchers note.
The researchers used data on rates of latent tuberculosis infection, active disease, treatment, diagnoses of drug-resistant tuberculosis and successful treatment, as well as data on types of drug resistance, HIV coinfection, and World Health Organization estimates of incidence across the four countries. They projected that while drug-resistance caused by inappropriate or incomplete treatment will drop, transmission of drug-resistant disease will continue to cause rising rates of disease that does not respond to the most effective currently available medicines. Current treatment and control measures will not reverse this trend, they conclude, saying the findings underscore the need for improved interventions to prevent transmission, and new, more effective treatments.