Syphilis role in HIV being studied in California

STD and HIV surveillance working together

For the past three years, syphilis outbreaks in men who have sex with men (MSM) have worried health officials because of what they indicate about a resurgence in high-risk behaviors. But are these syphilis outbreaks facilitating HIV transmission or is syphilis contained mostly to MSM who are already HIV-positive?

California’s sexually transmitted disease (STD) and HIV health officials hope to answer that question with assistance from the Centers for Disease Control and Prevention (CDC) and its new detuned testing technology.

"We need to get some better information quickly, and so we are combining our HIV and STD efforts to find the answer," says Gail Bolan, MD, the state’s director of STD control.

In March, the state requested the Centers for Disease Control and Prevention (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. The CDC will be providing two EIS officers, while the state’s existing EIS officer will help coordinate the effort.

Just how much STDs contribute biologically to facilitating HIV transmission is an ongoing debate. Three years after large studies in Africa attempted to quantify the impact, the results have been inconclusive. Most recently, an analysis of a study in Uganda concluded that STD control has a minimal impact in an already mature HIV epidemic. While it’s clear the United State’s syphilis epidemic is starting a new cycle, the HIV epidemic is harder to qualify, Bolan says.

In the United States, CDC behavioral surveillance suggests so far that the syphilis outbreaks haven’t 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 says. "Our data really don’t support that. We talk to a lot of men who claim they are having a lot of sex with partners of unknown status. So we really need to know what is going on here."

Until now, this kind of research hasn’t been easy. First, controlling for behaviors is notoriously difficult. Second, it’s hard to always know which infection came first: syphilis or HIV. With detuned testing of specimens, however, 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 says.

"That would tell you if the infection was more likely related to an ulcer," she explains. "You could then compare the results with people who are not infected with primary syphilis but who have similar behaviors."

California’s collaborative effort could be a model for other areas of the country where syphilis and HIV coexist. "We hope the model we use in California can be a model the South can use to prove to the CDC that syphilis has really contributed to HIV," Bolan notes. "They want hard data, and this can help get some information fairly quickly."

So far, traditional syphilis control efforts have not been able to quell the outbreaks, which continue to spread into other communities.

"Unless there is a collective approach between HIV and STD prevention, it’s going to be hard for STD control to do it alone," she says. "We can use our control, but we really need some new innovative strategies," she says. The state could have preliminary results by this summer, Bolan adds.