The Centers for Disease Control and Prevention attributed the decline to an ongoing national campaign aimed at improving surveillance, screening and coordination of syphilis prevention and treatment programs.
The Atlanta-based CDC said that 5,979 cases of primary and secondary syphilis, or 2.2 cases for every 100,000 people, were reported in the nation in 2000, representing a 9.6 percent drop from the previous year.
Primary and secondary syphilis are the initial stages of the disease, when it can be cured with antibiotics. The rate of tertiary syphilis, the final and most destructive stage of the disease, was not available.
The government wants to cut annual cases to fewer than 1,000 by 2005 and boost the number of syphilis-free counties to 90 percent its definition of eradication from the current level of about 80 percent.
"We're definitely talking about something that is possible and readily achievable," said Dr. Ronald O. Valdiserri, CDC deputy chief of sexually transmitted diseases.
Pockets of the disease remain, mostly in the South and among poor blacks and Hispanics. And infections are on the rise among gay and bisexual men. That concerns experts because they suspect it reflects more risky sexual behavior, which could lead to a rise in HIV infections.
Mother-to-child syphilis transmission is down more than half since 1997, and the rate among blacks has dropped 40 percent.
Syphilis appears first as a sore, usually on the genitals, then develops as a rash. It can be cured with penicillin, but left untreated it can damage the heart, eyes, brain and other parts of the body.
© MMI, CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press and Reuters Limited contributed to this report