XDR-TB patient in U.S. highlights global reach of infectious disease

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While health officials seek fellow passengers, researchers seek a vaccine

If an argument is needed against prioritizing United States medical research dollars simply on the basis of disease burden in the U.S., global health advocates in Washington, DC didn’t have to look any farther this week than the National Institutes of Health campus in Maryland. That’s where a woman who recently flew from India to Chicago and has since been diagnosed with extensively drug-resistant tuberculosis is now being treated.

While the U.S. Centers for Disease Control and Prevention  is notifying passengers on the woman’s international flight, and working with local health officials to find other people who spent time with her in Illinois, Tennessee and Missouri, as the New York Times reported Monday, the agency also has issued a statement saying the woman’s case posed little risk to the public. Why the concern then?

Because even with low risks of transmission and high cure rates, ordinary tuberculosis demands months of difficult and harsh treatment before it is cured and stops posing a threat to individual patients and to public health. The  strain of tuberculosis the woman is sick with — also known as XDR-TB — resistant to at least two first line drugs, and at least one injected second line drug, requires years of harsh and closely supervised treatment with less likelihood of success. While ordinary tuberculosis has about a 90 percent cure rate, the CDC estimates that a cure is possible in about 30- to-50 percent of patients with extensively drug resistant disease. In parts of the world where the disease is more common, the toll (in India, home to the world’s highest TB burden and where the current patient at NIH traveled from, tuberculosis has been estimated to kill one person every two minutes, and 750 people a day) is exacerbated by the resources treating and controlling the disease demands.

“You can treat 25 patients with regular tuberculosis for every one patient with XDR-TB,” Dr. Lewis Schrager said Tuesday. Dr. Schrager is an infectious diseases and vaccine specialist and vice president of Scientific Affairs at Aeras, a nonprofit biotechnology outfit working to develop new tuberculosis vaccines. The challenge of treating extensively drug resistant tuberculosis is difficult in the U.S., he notes, and overwhelming  in developing countries.

On the other hand, what makes tuberculosis bacteria resistant to treatment drugs would not make it resistant to a vaccine.

While distance offers diminishing protection in an increasingly mobile world, “vaccines are the ultimate game-changer,” Dr. Ann Ginsberg, Aeras chief medical officer said.

“Tuberculosis is airborne,” Dr. Ginsberg notes, adding that includes by coughing, sneezing or shouting. “People travel all over the world. There is nothing to prevent us getting tuberculosis either at home or abroad.”

That’s why while one tuberculosis patient has attracted attention in the U.S. this week,  the worldwide nine million people diagnosed with active tuberculosis and 1.5 million who die of the disease each year also should, the way global health advocates and researchers see it.

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