Richard L. Bruno is chairperson of the International Post-Polio Task Force and director of The Post-Polio Institute at Englewood Hospital and Medical Center. Please e-mail questions directly to him at ppseng@aol.com.

Note: This column is for information purposes only and is not intended as a substitute for professional medical advice.

Q: My mother had polio when she was pregnant with me. At age 35 I began suffering symptoms that match PPS very well. I am wondering if I caught polio in the womb from my mother.

The simple answer is no; kids inside the womb did not catch polio from their mothers. During the epidemic years, nearly a thousand women in Los Angeles and Illinois were studied who developed polio during pregnancy. Not one baby was born with symptoms even vaguely similar to those of polio. It is thought that a mother's own antibodies against poliovirus passed to the fetus and protect against developing polio in the womb.

However, between 1897 and 1956 there were 150 cases of polio reported in children who were less than six months old. Among these were four instances of babies delivered with an arm or leg that had obviously been paralyzed by polio many weeks before birth. It is likely that something very unusual happened in these four cases. Perhaps the mother was not able to make enough poliovirus antibodies to protect herself and the baby, her antibodies were not passed to the baby, or an abnormality of the placenta allowed poliovirus to infect the fetus.

Still, pregnancy and polio was a dangerous combination. The L.A. and Illinois studies found that pregnant women who developed polio were about five times more likely to die. The fetus was also at risk. Any severe illness in a mother that causes a high fever increases the possibility of miscarriage, and polio was no exception. In the L.A. study, 22 percent of pregnant women with polio miscarried. This percentage is not higher than in the general population. And autopsies on miscarried fetuses showed no evidence of polio infection. However, the doctors who studied the mothers believed the babies would have lived had it not been for the mothers' polio. So, the chances of your having caught polio from your mother are "infinitesimal." If you had, you would have been born with paralysis.

Q: I have attended three of your post-polio conferences in the South and am a member of a large Southern post-polio support group. I was the only African American at those conferences and am the only black person in my support group. In fact, I've never met another African-American who had polio. Could it be that few black people got polio?

It has always been amazing to me that I have met only a handful of African-American polio survivors during the past 18 years as I've spoken to post-polio conferences across America. It is also remarkable that only about two percent of the patients treated at the The Post-Polio Institute are African-American. This poses the fascinating possibility that there is something about race, something in the genes, that makes some people less likely to get polio.

In 1935 the U.S. Public Health Service canvassed 200,000 households asking about polio. The survey found that 265 percent more white than African-American children had contracted polio. This striking difference could not be explained by greater poverty among African-Americans. In Hawaii between 1938 and 1947, whites had almost three times more polio than Japanese, about four times more polio than Chinese and nearly six times more polio than Filipino residents. And there's another decidedly genetic factor associated with polio: The 1935 survey found that 40 percent more males than females got polio.

There are many ways your genes could have made you more susceptible to polio. If the immune system were less active or responded less quickly when the poliovirus entered the bloodstream, you might not as quickly have made the number of poliovirus antibodies needed to stop neurons from being infected. An even more intriguing genetic factor is the fact that a poliovirus receptor (PVR) must exist on a neuron in order for poliovirus to get inside that neuron and do damage. It may be that the PVR gene, which is on chromosome 19, is more active in white males and least active in African-American females. Of course there are a host of non-genetic factors that determine who will get polio: the strength of the poliovirus, how much virus gets inside of you, as well as both physical and emotional stress. And, as evidenced by your own experience and the fact that polio is still epidemic in Africa, neither African-Americans nor Africans are immune from polio. One of the promises of genetic engineering is the possibility of turning off the PVR gene. Without poliovirus receptors there could be no poliovirus infection of neurons and no need for a polio vaccine.