Rare disease proves tough to diagnose

Drug-resistant pediatric tuberculosis a growing global health threat affecting young children

When a 2-year-old returned sick from a visit to India, US doctors suspected tuberculosis even though standard tests said this was not so.

It would take three months to confirm she had an extreme form of the disease - a saga that highlights the desperate need for better ways to fight TB in youngsters in countries that can't afford such creative care.

Drug-resistant tuberculosis is a global health threat, and it's particularly challenging for young children who are even harder to diagnose, much less treat.

Doctors at Johns Hopkins Children's Center in Baltimore, Maryland, are reporting how they successfully treated one of the few tots ever diagnosed in the United States with the worst kind - extensively drug-resistant TB, or XDR-TB - that's impervious to a list of medicines.

"This was so difficult, even when we had all these resources," said Johns Hopkins pediatric TB specialist Sanjay Jain, who co-authored the report being published on Monday in The Lancet Infectious Diseases. The child now is 5 and healthy, but Jain calls the case "a wake-up call to the realities of TB".

Tuberculosis is a bacterial infection that usually strikes the lungs, spreading through coughs and sneezes. A recent World Health Organization report says TB affected nearly 10 million people worldwide last year, including 1 million children.

This is double earlier child estimates, reflecting some countries' better counts. Many experts suspect the toll is still higher because children in hard-hit countries can die undiagnosed.

Anna Mandalakas, director of the global tuberculosis program at Texas Children's Hospital and Baylor College of Medicine, said that in much of the world, doctors "don't have anything like a CT scan to use to help them with this. They just have to use a stethoscope and a scale and their clinical judgment."

The Johns Hopkins patient, who wasn't identified, returned from a three-month family trip to India with a high fever. A series of tests yielded no diagnosis, and no relatives were sick. But X-rays and CT scans found clues - a spot on her lung and some enlarged lymph nodes.

To diagnose adults, doctors check their sputum for TB germs. Children, especially those younger than 5, don't harbor nearly as much bacteria - and tots tend to swallow rather than cough out the mucus, Jain said.

Suspicious doctors threaded a tube into the girl's stomach for samples, so a laboratory could try to grow and identify any bacteria lurking in them.

Meanwhile, the child was prescribed four standard TB drugs. Her fever broke, and she gained weight - changes that in many TB-stricken countries would signal successful treatment.

But X-rays showed persistent lung inflammation. After a month, workers finally detected slow-growing TB germs in one of the laboratory samples, something to use for more complex testing.

Confirmation that she had the scary XDR-TB came 12 weeks after the girl's initial examination, Jain said. Three of the four drugs she was taking didn't work. Her fever returned and lung tissue began dying. Doctors switched her to five different, riskier, medications, but had no quick way to monitor if they were working.

So Jain tried something experimental, stemming from his research on using special low-radiation CT scans to track infections. A scan showed her lungs were starting to clear weeks into the new therapy. She was declared in remission after 18 months of treatment.

Drug-resistant strains of TB are on the rise, especially in India, China and Africa. The hardest-to-treat XDR form is very rare in the US, where patients are isolated from the public while being treated to prevent the strain spreading. The Centers for Disease Control and Prevention has counted 74 XDR-TB cases since 1993, two in children under 5.

(China Daily 11/17/2015 page10)