LOS ANGELES — Matthew Kennedy spent his 39th birthday at the hospital learning to walk again.

Three months ago, the Venice Beach resident started having trouble moving his legs. When a chest X-ray at a Santa Monica health center revealed a shadow in his lungs, he was quickly transferred to a highly specialized tuberculosis ward 25 miles across the county at Olive View-UCLA Medical Center in Sylmar.

Doctors think the bacterial disease attacked his nerves — unusual for TB, which typically infects the lungs. But rare is normal for the Olive View unit, one of only four such centers in the nation specialized in tuberculosis.

“Something that the average physician would only see maybe once in a lifetime, we see kind of routinely here,” said Dr. Glenn Mathisen, director of the infectious diseases department at Olive View.

The high-tech isolation unit opened last August as part of a $53 million federally funded renovation of the public hospital’s emergency room to equip it for a bioterrorism attack. For now, it serves highly infectious or difficult-to-treat tuberculosis patients, reflecting positive and negative crosscurrents in TB medicine: Infections are down dramatically but getting more complicated.

“You’re getting to those that are much more challenging to treat medically, that require longer hospitalization,” said Dr. Frank Alvarez, who directs the county’s tuberculosis control program.

For Olive View, which opened 90 years ago as the largest TB sanitarium west of the Mississippi, the new ward represents a bit of deja vu with a cutting edge. “We’ve come sort of full circle,” Mathisen said.

The facility, which can handle up to 30 patients, has a state-of-the-art, pressure-controlled air circulation system designed to keep the airborne disease from spreading. An alarm system sounds if anything is amiss, and air leaving the ward gets zapped with UV light to kill any tuberculosis germs.

Once known as consumption, the killer disease that claimed Emily Bronte and Frederic Chopin, tuberculosis is now viewed as a bygone threat by many in developed countries.

But the illness remains widespread in poorer countries and still surfaces in the United States in places like Los Angeles, with large and diverse immigrant communities.

“It’s still a fatal disease,” Alvarez said. “It needs to be taken still very seriously in terms of public health and safety.”

TB cases in Los Angeles County have dropped nearly 70 percent over the last two decades. Still, 680 infections were confirmed last year and nearly 80 percent of those involved people born in other countries, primarily Mexico, the Philippines, Vietnam and China.

Olive View’s ward is designed to accommodate the most demanding cases, thereby freeing up beds in infectious disease wards at other county hospitals. Mathisen said the severity of the 68 tuberculosis cases that have come through the unit in the past year caught the staff by surprise. “They’re sicker than we thought they would be,” he said.

Many of the center’s patients are homeless or low income and have a host of other conditions that complicate tuberculosis treatment, including diabetes, HIV, heart disease, substance abuse or mental illness.

By keeping the patients for a few months, “we have time to counsel and educate them on their different illnesses” and medications, said Leona Mason, a nurse practitioner in the ward. “It’s a lot for some of these people to take on.”