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IAS 2013: Strategies to Detect and Treat Gay Men with Acute HIV Infection

The detection and control of acute (very recent) HIV infection may be a powerful HIV prevention measure for epidemics in men who have sex with men (MSM), Eugène Kroon of the Thai Red Cross AIDS Research Center reported at a late-breaker session at the recent 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention in Kuala Lumpur. Immediate HIV treatment was associated with rapid falls in viral load and sustained behavior change.

[Produced in collaboration with Aidsmap.com]

An HIV testing program in Bangkok was able to identify a considerable number of men who have sex with men who had only been infected with HIV for a few weeks, Kroon reported. Moreover, most of those identified accepted the offer of immediate antiretroviral therapy (ART), resulting in dramatic drops in viral load in blood and semen.

The HIV epidemic in young Thai men who have sex with men continues to grow at an alarming speed. One of the key Bangkok HIV testing centers recently reported that, in 2011, 28.3% of new patients were already infected with HIV. Among existing patients, 8 in 100 newly acquire HIV each year.

As in many other situations where there are high rates of partner change, it is likely that individuals who have themselves been very recently infected with HIV but are unaware of the fact make a disproportionate contribution to the number of new infections which occur.

Researchers in Bangkok have been working to identify, treat, and follow a cohort of people with acute HIV infection, primarily for basic science purposes. They aim to describe the clinical, immunological, and virological characteristics of acute infection, to inform the development of vaccines. Furthermore, a better understanding of the effect of HIV treatment during acute infection may help the development of a functional cure. But the project also aims to describe the demographics and behavioral risk factors of those identified with acute HIV infection.

Blood samples of people attending HIV testing clinics in Bangkok were screened for acute HIV infection using nucleic acid testing (as is used in screening blood donors), a p24 assay, antibody testing, and Western Blot testing. As each of these has a different "window period" during which it cannot detect a recent infection, the contrasting test results can suggest the likely duration of a person’s infection.

Over 4 years, starting in 2009, a total of 69,911 samples were tested and 136 were found to be cases of recent infection. Almost all were samples from men who have sex with men.

Kroon presented data on 90 of these MSM. Most were in their twenties or early thirties and were thought to have been infected for between 10 and 23 days. The laboratory facilities in place meant that their acute infection was usually identified within 3 days of samples being taken. The individuals were immediately contacted, counseled, and invited to go on ART -- 88 of the 90 did so.

As a result, viral load levels dropped dramatically. Whereas the average blood plasma viral load was around 5 log copies/ml for the first 2 weeks, 22% of the men were undetectable by week 4, rising to 55% at week 8, 80% at week 16, 91% at week 24, and 97% at week 48.

Similarly, 59% of seminal plasma samples were undetectable by week 2, 73% by week 4, 95% by week 12, and 100% by week 24.

Kroon noted that, among men not taking antiretroviral treatment, seminal viral load usually peaks a month after infection, whereas there was a sharp and rapid decline in this cohort. This will have a substantial impact on the risk of onward transmission.

What’s more, although the researchers did not describe in detail the risk reduction counseling which was provided, it appears to have been effective.

At baseline, 55% of the men had reported having between 2 and 4 sexual partners in the previous month, and 30% reported having more than 5. By week 24, these figures had dropped to 32% and 7%, respectively.

Moreover, at baseline 84% of men reported having had unprotected anal intercourse in the previous 4 months, including 57% reporting it with a casual partner. By week 24, the figures had dropped to 25% and 8%.

Kroon said that, whereas he was not particularly surprised to see these reductions in the first few months after diagnosis, he was very surprised that the behavior change was maintained up to week 48 (11 months). For each of the behavioral indicators just reported, there were no statistically significant differences between the figures at weeks 24 and 48.

In the Bangkok program, there appears to be a synergy between the effects of immediate antiretroviral therapy and the impact of behavior change. Kroon said that the preliminary results of modeling work conducted by David Wilson suggested that when an individual with acute infection receives the intervention, it may avert 78% of onward transmissions during the first 6 months after infection.

8/13/13

Reference

F van Griensven, N Phanuphak, EDMB Kroon, et al. Acute HIV infection detection and control reduces HIV infectiousness and transmission risk behavior among men who have sex with men in Bangkok, Thailand. 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2013). Kuala Lumpur, June 30-July 3, 2013.Abstract WELBC03.