Viral Loads Among HIV-Infected Persons Diagnosed With Primary and Secondary Syphilis in 4 US Cities: New York City, Philadelphia, PA, Washington, DC, and Phoenix, AZ.

BACKGROUND: Incident syphilis among HIV-infected persons indicates the ongoing behavioral risk for HIV transmission. Detectable viral loads (VLs) among coinfected cases may amplify this risk.
METHODS: Primary and secondary cases reported during 2009-2010 from 4 US sites were crossmatched with local HIV surveillance registries to identify syphilis case-persons infected with HIV before or shortly after the syphilis diagnosis. We examined HIV VL and CD4 results collected within 6 months before or after syphilis diagnosis for the coinfected cases identified. Independent correlates of detectable VLs (≥200 copies/mL) were determined.
RESULTS: We identified 1675 cases of incident primary or secondary syphilis among persons with HIV. Median age was 37 years; 99.5% were men, 41.1% were African American, 24.5% were Hispanics, and 79.9% of the HIV diagnoses were made at least 1 year before syphilis diagnosis. Among those coinfected, there were no VL results reported for 188 (11.2%); of the 1487 (88.8%) with reported VL results, 809 (54.4%) had a detectable VL (median, 25,101 copies/mL; range, 206-3,590,000 copies/mL). Detectable VLs independently correlated with syphilis diagnosed at younger age, at an sexually transmitted disease clinic, and closer in time to HIV diagnosis.
CONCLUSIONS: More than half of syphilis case-persons identified with HIV had a detectable VL collected within 6 months of the syphilis diagnosis. This suggests virologic and active behavioral risk for transmitting HIV.