Hospital and public health laboratories across the country are now detecting early-stage HIV infections much sooner than previous tests since the launch of Abbott’s ARCHITECT HIV Ag/Ab Combo assay, a combination antigen-antibody test, in 2010. Researchers reported finding early stage infections in places not known for high HIV prevalence like Sioux Falls, SD, where HIV infections are believed to be low. Experts presented their observations this week at an Abbott-sponsored workshop at the American Association for Clinical Chemistry annual meeting.

This year marks 30 years since the first US reports of HIV and AIDS. While there have been significant advances made in the detection and treatment of the virus, each year more than 56,000 people in the US are infected with HIV, according to the US Centres for Disease Control and Prevention (CDC) — and one in five people don’t know they have it. The CDC also has reported that more than half of new HIV infections are transmitted by recently infected, highly contagious individuals unaware of their HIV status.

“Recently infected individuals are responsible for so many new HIV transmissions, mainly because they don’t know they’re infected,” said Peter Leone, MD, professor of medicine, University of North Carolina at Chapel Hill. “Identifying more people earlier offers a significant opportunity for counselling, which can reduce high-risk behaviours and also initiate antiretroviral treatment for early-stage infection, which has now been shown to significantly reduce transmission of HIV.”

Leone noted that fourth-generation HIV testing detects the majority of acute HIV, or newly infected, cases and can help public health officials gauge community rates of HIV infection. He advocates screening for acute HIV in sexually transmitted disease clinics and in HIV testing sites that serve populations of homosexual and bisexual men. “Diagnosis of acute HIV can identify high transmission networks so that HIV prevention activities can be utilized. It is a valuable diagnostic asset that should be universally adopted by public health organizations,” said Leone.

According to an article published in the New England Journal of Medicine on May 19, 2011, fourth-generation HIV testing, like the ARCHITECT HIV Ag/Ab Combination Assay, “can increase the number of patients with acute HIV-1 infection whose condition is diagnosed at a time when they are most infectious to others.” The publication further noted the newly infected are most contagious because of initial high viral loads and the lower transmission risk among those with chronic infections probably results from neutralizing antibodies not found at the acute phase.

The Abbott ARCHITECT HIV Ag/Ab Combo assay is the first test approved in the United States that can simultaneously detect both HIV antigen and antibodies. HIV antigen is a protein produced by the virus immediately after infection, whereas antibodies are developed days later as the body works to fight off the infection. Studies have demonstrated that Abbott’s test may detect HIV up to 20 days earlier than antibody-only tests, which is important in controlling the spread of the virus. This is particularly important because individuals who receive false negative results remain unaware that they have HIV and are not able to take proper precautions.

At Avera McKennan Hospital and University Health Centre in Sioux Falls, SD, three acute HIV infections have been detected according to Leo Serrano, FACHE, DLM (ASCP), director of laboratory services. “Despite a low HIV incidence in the region, we have discovered recent HIV infections before the individuals became antibody positive,” said Serrano.

“Our experience in finding acute infections in Sioux Falls upholds the value of screening using a fourth-generation test even in low prevalence areas where clinicians are unlikely to suspect HIV when seeing someone with an early-stage infection,” he added.

Improved detection of acute HIV infections also can have a favourable impact on US health care costs. According to a study conducted by the HIV Prevention Trials Network, initiation of antiretroviral therapy by HIV-infected individuals substantially protected their HIV-uninfected sexual partners from acquiring HIV infection, with a 96 percent reduction in risk of HIV transmission. Also, it was reported in a 2006 article in Medical Care, a journal of the American Public Health Association, that every case of HIV that is prevented saves an estimated $ 618,000 in lifetime treatment costs.

For in vitro diagnostic use: the ARCHITECT HIV Ag/Ab Combo assay is a Chemiluminescent Microparticle Immunoassay (CMIA) for the simultaneous qualitative detection of Human Immunodeficiency Virus (HIV) p24 antigen and antibodies to HIV type 1 (HIV-1  roup M and group O) and/or type 2 (HIV-2) in human serum and plasma (EDTA and heparin). The ARCHITECT HIV Ag/Ab Combo assay is intended to be used as an aid in the diagnosis of HIV-1/HIV-2 infection, including acute or primary HIV-1 infection. The assay may also be used as an aid in the diagnosis of HIV-1/HIV-2 infection in pediatric subjects (i.e., children as young as two years of age) and in pregnant women. An ARCHITECT HIV Ag/Ab Combo reactive result does not distinguish between the detection of HIV-1 p24 antigen, HIV-1 antibody, or HIV-2 antibody.

The ARCHITECT HIV Ag/Ab Combo is not intended for use in screening blood or plasma donors. The effectiveness of ARCHITECT HIV Ag/Ab Combo for use in screening blood or plasma donors has not been established. However, this assay can be used as a blood donor screening assay in urgent situations where traditional licensed blood donor screening tests are unavailable or their use is impractical.

Assay results should be interpreted in conjunction with the patient's clinical presentation, history, and other laboratory results. If the results are inconsistent with clinical evidence, additional testing is suggested to confirm the result. The performance of this assay has not been established for individuals younger than two years of age.

United States Federal law restricts this device to sale and distribution by or on the order of a physician, or to a clinical laboratory.

The CDC estimates that there are 56,000 new cases of HIV in the United States annually, and that every nine and a half minutes, someone in the country is infected with HIV. UNAIDS estimates that 2.7 million people throughout the world are newly infected with HIV each year. Leading risk factors for HIV infection include high-risk heterosexual contact, intravenous drug use, and male-to-male sexual contact.

Abbott is a global, broad-based health care company devoted to the discovery, development, manufacture and marketing of pharmaceuticals and medical products, including nutritionals, devices and diagnostics. It is a global leader in in vitro diagnostics and offers a broad range of innovative instrument systems and tests for hospitals, reference labs, molecular labs, blood banks, physician offices and clinics.