A national blue-ribbon panel warned that child abuse threatens to corrode the nation's social fabric and existing programs appear powerless to stop it. The U.S. Advisory Board on Child Abuse and Neglect proposed that health care workers and others visit new parents in their homes to offer advice, discuss health care and make sure the parents know how to care for a child. The report's release coincided with the start of the Ninth National Conference on Child Abuse and Neglect in Denver. The report was to be discussed at a hearing planned today in Denver by the House Select Committee on Children, Youth and Families.