BOSTON — The diagnosis of syphilis is often delayed in HIV-positive patients, as it is characterized by a wide range of symptoms that may not be recognized as infection with Treponema pallidum, according to Dr. Lawrence A. Siegel of the division of international medicine and infectious diseases, Cornell University, New York.
After declining to an all-time low in 2000, the rate of syphilis in the United States rose from 3 per 100,000 population in 2001 to 5.7 per 100,000 in 2006. Syphilis has increased particularly dramatically in men who have sex with men (MSM), who made up 4% of cases in 2000 but who represented 64% of cases in 2006, Dr. Siegel reported in a poster session at the 15th Conference on Retroviruses and Opportunistic Infections.
Nationwide, approximately 60% of cases of syphilis now are seen in HIV-positive, urban MSM, but in New York City, 97% of syphilis cases are in MSM.
To more fully characterize this coinfected population in New York City, Dr. Siegel and his colleagues undertook a retrospective chart review of all HIV-positive MSM diagnosed with incident syphilis at the Cornell HIV clinic between January 2001 and December 2007.
A total of 118 cases of syphilis were identified. Stage at diagnosis was primary in 8 patients, secondary in 80, early latent in 17, and late latent in 13, Dr. Siegel reported. Three patients had neurosyphilis.
Median age of the patients was 38 years. A total of 33% were white, 30% were black, 34% were Hispanic, and the rest were classified as “other.” The HIV RNA level was less than 400 copies/mL in 56%, and median CD4 count was 399 cells/mm
Clinical presentations were varied, and the diagnosis was delayed in nearly half of the patients overall. (See box.)
A total of 96% of patients had a fourfold decrease in RPR titer at 1 year, but reinfections were common, at a rate of 10% a year.
A multivariate analysis found that higher baseline RPR titer and diagnosis of latent syphilis were associated with a longer time until the RPR titer became negative, Dr. Siegel reported at the meeting, which was sponsored by the Foundation for Retrovirology and Human Health and the Centers for Disease Control and Prevention.
Different treatment regimens (one or three doses of 2.4 million U benzathine penicillin, or doxycycline 100 mg twice daily for 30 days) weren't tied to a longer time until RPR negativity, the researchers said. Cases of early syphilis in this population are often not identified, so a higher index of suspicion is needed. More frequent serologic testing also is warranted.
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