Q. A friend of mine had poliomyelitis when he was a kid and now the disease seems to be coming back in his old age. Have you heard of this?

The National Center for Health Statistics estimates that more than 440,000 poliomyelitis survivors in the United States may be at risk for post-polio syndrome (PPS), a condition that strikes poliomyelitis survivors decades after they've recovered from an attack of the poliomyelitis virus.

Various researchers estimate that PPS affects from 40 to 80 percent of poliomyelitis survivors.

Common PPS symptoms include: muscle and joint weakness, fatigue, pain, muscle atrophy, difficulty breathing or swallowing, skeletal deformities, cold intolerance, and temporary interruptions of breathing while sleeping.

PPS usually progresses slowly. It is rarely life-threatening. There is no known cause for PPS. Unlike poliomyelitis, PPS is not contagious.

If a person suffered from a severe case of poliomyelitis, it is likely that the PPS that strikes later will also be severe. Those who had minimal symptoms from the original illness usually will have only mild symptoms when they get PPS.

The risk of developing PPS is greater if you acquired poliomyelitis as an adolescent or adult, rather than as a young child. Women get PPS more often than men.

There is no effective treatment for the syndrome itself. Doctors recommend that poliomyelitis survivors get the pr