A better way to diagnose HIV

July 15, 2015

The most dangerous phase of HIV infection is the “acute phase” – the first two months after infection. During this initial period, the virus is at its peak and eagerly awaits the chance to spread to another person. In fact, it is estimated that over half of new infections occur during this initial period.

To make matters worse, traditional HIV testing can be inaccurate during this acute phase. Traditional tests look for antibodies – a protein produced by the body's immune system. But those antibodies take several weeks to develop, so a person carrying HIV can sometimes receive a false negative test result, and remain unaware of their infection. They feel fine, they suspect nothing, and the virus spreads.

Researchers in British Columbia, led by Dr. Michael Rekart and Dr. Mark Gilbert, have implemented and studied a new way to diagnose HIV during this acute phase.

The new test is called NAAT, which stands for “nucleic acid amplification test.” Rather than testing for antibodies, NAAT tests for viral DNA, which is present the very instant that a person is infected.

The study focused on gay men in downtown Vancouver, the population with the greatest number of new HIV infections each year in British Columbia.

The results were remarkable. During the course of the study, 25 men were diagnosed with HIV using NAAT – men that would have otherwise received a false negative result. The researchers estimate that this averted 25 additional HIV infections, resulting in provincial savings of approximately $14 million.

In conjunction with the new test, the researchers collaborated on a public awareness campaign with local community groups, focused primarily on gay men living in Vancouver’s Downtown Eastside. The campaign was called HIV: Hottest at the Start – a reference to the fact that a relationship is “hottest” when a couple first meets, and that HIV is “hottest” when a person is first infected.

The response from the gay community has been very positive. “People are much more aware now that you’re most infectious when you’re first infected. And they’re also aware that there is a test available through our clinics that can diagnose you early on,” said Dr. Rekart. “The other thing we confirmed was that when people know they are HIV-infected, they change their behaviour on their own. In other words, people don’t want to infect other people. So just telling them that they’re HIV-positive actually changes their behaviour in many cases. When you make a diagnosis, it reduces high-risk behaviour by 50%.”

As a result of this research, plans are to expand the test to more clinics, and they are optimistic that it will one day become the standard diagnostic test. “A test like this is most cost-effective when you use it in clinics where you’re most likely to find acute infection,” added Dr. Rekart. “That’s basically in clinics that serve populations with high rates of HIV, such as clinics for gay men.”

The researchers calculated that one additional HIV infection is prevented for every person diagnosed as HIV-positive with this test (a conservative estimate – the number may actually be higher). Each diagnosis also saves the health care system about half a million dollars per person, although that figure can vary depending on the jurisdiction and the age of the patient.

Most importantly, these diagnoses prevent human suffering and improve the patient’s chances of survival.

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