Although a number of studies have demonstrated that a substantial proportion of HIV-infected individuals engage in high-risk sexual practices with HIV-negative or unknown-serostatus partners, little information is available on the extent to which these behaviors are prevalent among individuals newly infected with HIV, or how risk behavior after the notification of HIV infection compares with pre-notification behavior. If risk behaviors with uninfected individuals are high at a time when the plasma (and presumably genital tract) viral load is high, a substantial proportion of new infections could result from this limited pool of highly infectious, highly sexually active individuals unaware of their HIV infection. From a prevention perspective, considerable efforts and resources should therefore be directed to the identification, counseling, and possibly the early treatment of individuals with newly acquired HIV.

In the current study, the researchers assessed the potential for early secondary HIV transmission among newly infected individual men who have sex with men (MSM) by determining the prevalence of high-risk behavior reported prospectively by participants before receipt of their initial positive HIV test results. Potential infectiousness was determined by measuring blood and seminal plasma viral loads before participants initiated antiretroviral therapy (ART).

The researchers studied the risk behavior of MSM seroconverters from the HIVNET Vaccine Preparedness study cohort. Researchers used risk assessment questionnaires administered before receipt of the first positive HIV antibody result; plasma and seminal viral load measurements; risk assessments one month and quarterly after receipt of the first HIV-positive test, and generalized estimating equation modeling techniques to analyze behavioral trends. Men who were at high risk of transmitting HIV were defined as those who became HIV-infected and reported insertive or receptive unprotected anal intercourse (UAI) with reported HIV-negative or unknown-serostatus partners during the interval between their last HIV-negative antibody test and their first HIV-positive antibody test. Low-risk transmitters were infected participants who did not report these behaviors with such partners.

"We found that a large proportion of MSM seroconverters reported sexual practices that may have resulted in secondary HIV transmission during the seroconversion period, before receiving knowledge of their recent infection," the researchers wrote. "Self-reported high-risk transmitting behavior declined sharply after the receipt of the HIV-positive test, indicating that the identification of recent seroconverters should be a priority of prevention program."

Of 66 seroconverters, more than half reported UAI with HIV-negative or unknown-serostatus partners during seroconversion, with 27 percent reporting insertive UAI with an HIV-negative partner. Plasma and semen viral loads suggested a high level of infectiousness. Compared with risk behavior during seroconversion, UAI with HIV-negative or unknown-serostatus partners was reduced after the receipt of positive results; however, a substantial proportion of subjects reported high-risk behaviors for transmission during 12 months of follow-up.

"Our results indicated that to reduce the risk of secondary HIV transmission during the early seroconversion period, enhanced efforts are required both to identify newly infected individuals as early as possible, and to provide risk-reduction counseling more effectively throughout at least the first year after infection. We found some evidence that individuals with symptoms consistent with HIV seroconversion may be at higher risk of secondary transmission. If real, this association would suggest that providers should have heightened sensitivity not only to testing high-risk individuals presenting with non-specific viral symptoms, but also providing risk-reduction counseling both for HIV acquisition and transmission during the pre-testing counseling session," the researchers concluded.

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