In descending order of severity: stillborn infants and infants who died up to 12 months after birth (dead); infants with strong evidence of syphilis, based on testing indicative of syphilis, physical signs or symptoms of syphilis, and/or (in mother untreated or inadequately treated for syphilis) elevated cerebrospinal fluid (CSF) white blood cell count or CSF protein concentration absent other causes (see “Materials and Methods”) (morbid); infants lacking evidence of infection present in morbid cases, with normal physical examination reported (nonmorbid); and infants lacking evidence of infection present in morbid cases, without normal physical examination reported (unknown). Overall, rates of dead, morbid, and nonmorbid cases of CS all declined during 1999 through 2013. While rate of dead cases declined slightly and very gradually throughout 1999 through 2013, rates of morbid and nonmorbid cases declined most during 1999 through 2005.