A common virus best known for blinding AIDS patients may cause some cases of crib death, which claims the lives of more babies than any other problem, researchers said Saturday.

A German university study, presented at an American Society for Microbiology conference in San Diego, found a link between crib death, also known as sudden infant death syndrome (SIDS) and the common cytomegalovirus (CMV).SIDS in the United States claims the lives of about one in 1,000 infants during the first year of life, with many cases occurring after just three months. It is the leading cause of death among infants before their first birthday.

Doctors have searched for years to find the definitive cause of SIDS with no real success.

It is known that babies exposed to cigarette smoke, both in the womb and after birth, are more likely to die of SIDS. Babies put to sleep on their stomachs are also more likely to die, and campaigns to get parents to put babies down on their backs have resulted in a dramatic decrease in the number of SIDS deaths.

Earlier studies have also found a link between respiratory infections and SIDS.

Following on this, researchers at the University of Erlangen study looked for traces of CMV in babies that had died of SIDS, also sometimes known as crib death. They found the DNA of the virus in just under 18 percent of SIDS victims, compared to 7.1 percent of infants that had not died.

CMV, which causes serious lung and brain disorders in premature babies, is transmitted from mother to baby during pregnancy in about 1 percent of births. Every year about 1 percent of children and young adults acquire the virus, which remains with them for life.

The CMV virus can be transmitted easily through blood transfusions and sexual contact and is most problematic in people with weak immune systems such as infants, organ transplant patients and those with AIDS.

While the researchers said CMV may cause some cases of SIDS there was no way of determining if the infants were infected during pregnancy or after birth and if that had any relation to the incidence of SIDS.