By Liisa Randall, Consultant, NASTAD
Each year on June 27th, we mark National HIV Testing Day (NHTD) as an opportunity to further promote HIV testing as an important HIV prevention tool and as the critical first step to linking individuals living with HIV with medical care and support services that can help them stay healthy and improve their quality of life.
Missing an opportunity to diagnose acute HIV infection has important public health implications. Health departments play an important role in HIV testing in that health department HIV prevention programs conduct more than three million tests each year. During the acute phase of HIV infection, individuals are highly infectious and research has demonstrated that acute infection contributes disproportionately to HIV transmission. Research also suggests that treatment of early HIV infection with antiretroviral therapy (ART) may delay disease progression and may also decrease the severity of acute disease.
The diagnostic algorithm currently used in the United States in many cases consists of a repeatedly reactive immunoassay (IA), followed by a supplemental test, typically the Western blot (WB). However, the third- and fourth-generation IA tests used by many commercial and public health laboratories today detect HIV infection earlier than the Western blot. This means that early or acute infections are often missed. Specimens associated with acute infection may be reactive by third- or fourth-generation IAs, but they are often misclassified as negative by Western blot.
Newer testing technologies and strategies can help us to identify acute infections. To that end, the Centers for Disease Control and Prevention (CDC) has proposed a new diagnostic algorithm which was presented at the 2012 HIV Diagnostics Conference. In conjunction with NHTD, the CDC has published in the Morbidity and Mortality Weekly Report (MMWR) findings from two studies evaluating the proposed new HIV testing algorithm: Detection of Acute HIV Infection in Two Evaluations of a New HIV Diagnostic Testing Algorithm — United States, 2011–2013. The first study involved screening of adult emergency department (ED) patients and was conducted as a collaboration between the Arizona Department of Health Services and the Maricopa Integrated Health Systems. The other study, Screening Targeted Populations to Interrupt On-going Chains of HIV Transmission with Enhanced Partner Notification (STOP) was implemented in three jurisdictions: New York, North Carolina and San Francisco.
The evaluation findings indicated that implementation of the proposed new HIV diagnostic algorithm averted missed diagnoses in 32% of the HIV-infected patients in a Phoenix ED and 9% of those in the STOP study. As a result, the MMWR concludes that “With FDA’s approval of the Multispot HIV-1/HIV-2 rapid test for use as the second test in this algorithm in March 2013, laboratories can adopt this algorithm. The fast turnaround time for test results from most third- and fourth-generation IAs (<1 hour) and the Multispot rapid test (15 minutes) affords the opportunity to deliver same-day definitive test results to the majority of HIV-infected persons who are antibody-positive.”
Adoption of the new HIV testing algorithm could significantly enhance the effectiveness of health department-supported HIV testing programs. Infections that are missed by the current HIV testing algorithm would be identified, and identified at an earlier phase of infection. This would permit a more effective public health response and contribute to improved health outcomes through earlier engagement in care.
Has your health department or community-bases organization already implemented testing for acute HIV infection? Tell us about your successes and challenges by leaving a comment below.