Syphilis Role in HIV Being Studied in California: STD and HIV Surveillance Working Together

Are syphilis outbreaks facilitating HIV transmission among men who have sex with men, or is syphilis contained mostly to MSM who are already HIV-positive? California's STD and HIV health officials hope to answer that question with assistance from CDC and its new detuned testing technology.

In March, the state requested CDC to conduct an Epidemic Intelligence Service (EIS) investigation -- also known as an Epi Aid -- which can quickly mobilize resources for a health problem that needs immediate attention. CDC is providing two EIS officers, and California's own EIS officers will help coordinate the effort.

While it is clear the US syphilis epidemic is starting a new cycle, the HIV epidemic is harder to qualify, said Gail Bolan, MD, the state's director of STD control. CDC behavioral surveillance suggests so far that the US syphilis outbreaks have not facilitated HIV transmission in MSM because many men appear to be engaging in "sexual positioning" (HIV-positive men having sex with other positive men). But information from syphilis partner notification interviews suggests differently, Bolan said. "We talk to a lot of men who claim they are having a lot of sex with partners of unknown status," she said.

Previously, this research has not been easy. Controlling for behaviors is difficult, and it is hard to know which infection came first: syphilis or HIV. With detuned testing of specimens, the time of HIV infection can be pinpointed more precisely. The easiest way to measure the syphilis impact on HIV transmission is to conduct HIV testing in a cohort of MSM recently infected with primary syphilis, Bolan said. "That would tell you if the infection was more likely related to an ulcer," she explained. "You could then compare the results with people who are not infected with primary syphilis but who have similar behaviors."

So far, traditional syphilis control efforts have not been able to quell the outbreaks. "Unless there is a collective approach between HIV and STD prevention, it's going to be hard for STD control to do it alone," Bolan said. "We can use our control, but we really need some new innovative strategies," she said. The state could have preliminary results by this summer, Bolan added.

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