A Marine Corps captain who has been treated since March 2 for a suspected case of rabies is now listed in satisfactory condition and has been moved out of the intensive care unit.

Officials at Walter Reed Army Medical Center said yesterday that the marine, whose identity they have declined to release, is "thinking and talking clearly again, and is walking with the aid of a walker." He remains paralyzed only in his feet, they said.

However, medical authorities said they still don't know exactly what viral infection caused the encephalitis, or inflammation of the brain, and other rabies-like symptoms he suffered.

"It's unlikely he's had rabies, just as it's unlikely that he's had any number of other viral infections," said Dr. Kenneth Bernard, an epidemiologist with the Centers for Disease Control in Atlanta and the nation's leading expert on rabies, noting that the progress of the man's disease has followed no previously known disease pattern.

"It's not that we don't believe he doesn't have rabies, it's that we believe that we don't know what he has," Bernard said. All tests for rabies and for other viruses have been negative. Bernard said it is "very possible" there will never be an exact diagnosis in the case.

At the same time, he said, rabies cannot be ruled out completely. "It could be a very unusual case of rabies, just as it could be a very unusual case of something else," he said.

The marine's pattern of recovery has been similar to that of the only person known to have recovered completely from rabies, Bernard said. There is no known treatment for the disease, other than supporting the various vital systems. Other victims of rabies have lived an average of 25 to 26 days on life-support systems, he said. Untreated patients usually die in four to six days.

Hospital officials said their efforts now would focus on physical therapy.

Forty-nine hospital employes at Walter Reed, Fort Belvoir and Quantico Marine Base who came into contact with the marine received the last in their five-shot series of antirabies vaccine yesterday.