Q: Can polio recur in adult hood?

. . . I have heard that there is a chance of a recurrence of polio in those who had it as a child. J.D., Boston

Recurrence isn't a problem, but a different condition, post-polio syndrome, or PPS, is.

Unlike the herpes virus, the polio virus does not hide out in the body and become reactivated years later. But an estimated 25 to 50 percent of people who once had polio come down with post-polio syndrome decades later, according to the website of the National Institute of Neurological Disorders and Stroke. (Warning: This website, www.ninds.nih.gov, has a pretty gloomy take on treatments for PPS. It's true, as the site states, that there is no magic bullet for PPS, but helpful treatments are available.)

What happens after a bout of polio is that nerves that survive the viral attack in essence try extra hard to compensate for nerve function that is lost, growing extra sprouts, or axons, that connect with muscles, telling them to contract, said Dr. Julie Silver, a post-polio specialist who runs the International Rehabilitation Center for Polio, part of the Spaulding Rehabilitation Hospital branch in Framingham (www.polioclinic.org). After many years of normal functioning, the nerves with excessive sprouting may not be able to keep up with the increased metabolic demands and may begin to deteriorate or die.

The hallmark of PPS is new weakness in people who had polio decades earlier, she said. Estimates vary, but there are approximately 1 million polio survivors in the United States; there have been no new cases of polio in the United States since 1979.

With PPS, people don't wind up as paralyzed as they were with polio. But, unlike with polio, there is little hope of recovery because the problem is slowly progressing nerve damage, not getting over an acute infection.

Even in PPS patients who had bulbar polio, which affects the breathing and swallowing muscles, treatment can be quite effective. Silver said: "Even one session with a speech therapist can help."

JUDY FOREMAN