When HIV patients are diagnosed in the first few weeks after infection, they dramatically change their sexual behavior to reduce the risk of infecting others, researchers said here.
The change included an abrupt shift to partners who were also HIV-positive.
The finding underscores the value of early HIV diagnosis, said Wayne Steward, Ph.D., of the Center for AIDS Prevention Studies at the University of California at San Diego.
The period of so-called “acute HIV” - roughly a month from infection - is also when people are most infectious to others, Dr. Steward said at the 2007 National HIV Prevention Conference.
“It’s a very high-risk time, so it’s good to see people changing,” he said.
Dr. Stewart and colleagues reported on the Multi-Site Acute HIV Infection Study, sponsored by the National Institute for Mental Health, a pilot evaluation of elements of the acute period.
For this aspect of the study, they reported on 27 participants - most of them homosexual men - who completed assessments of their sexual behavior before and after an HIV diagnosis.
They were interviewed about five weeks after diagnosis and again at about 10 weeks.
The participants reported:
* A significant drop (P<0.05) in the number of sexual partners after diagnosis.
* A significantly increasing proportion (P<0.001) of HIV-positive partners.
* No significant change in the number of sex acts, but a significant increase (P<0.001) in sex using condoms.
The shift to partners who were already HIV-positive was striking, Dr. Steward said. After diagnosis, more than 95% of sex acts were with people who were also HIV-positive.
Specifically, he reported, after diagnosis the volunteers reported 209 sex acts, 204 of them were with people infected with HIV, while before diagnosis most sex took place with people who were HIV-negative or whose status was not known.
If people are diagnosed with HIV soon after they are infected, "they are willing to make dramatic changes in their behavior relatively rapidly," Dr. Steward said.
One implication is that more effective testing regimens might detect more people in the highly infectious acute stage and the subsequent change in behavior might help prevent transmission, he said.
The finding is "consistent" with studies in other groups, commented Richard Wolitski, Ph.D., of the CDC's Division of HIV/AIDS Prevention.
"Some people become abstinent for a while, some use condoms consistently, and others make choices about sexual partners based on their HIV status," said Dr. Wolitski, who was not part of the study.
But the research reinforces the need to identify people with HIV as early as possible, he said - one reason the CDC is now recommending that those at high risk for HIV infection get tested regularly.
He noted that "serosorting" as a prevention strategy is most effective when it's a person who is HIV-positive seeking others who are infected, since both partners are likely to be correct about their HIV status.
On the other hand, he said, HIV-negative people seeking HIV-negative partners could run into difficulties. A CDC study in 2005 showed that half of those in the study who thought they did not have the disease actually were HIV-positive.
The study was supported by the National Institute of Mental Health. Dr. Steward reported no conflicts.
Primary source: 2007 National HIV Prevention Conference
Steward WT, et al “A move toward serosorting following acute HIV diagnosis: part 1 of 4 on findings from the NIMH multi-site acute HIV infection study” Abstract C20-1.