Marion County Public Health Department, Epidemiology Request DR2370
Prepared by: Tammie L. Nelson, MPH, CPH and Bonny Lewis Van, Ph.D., FACB, HCLD (ABB)

The Marion County Public Health Department’s Ryan White Services Program (RWSP) oversees Ryan White Part A, C, and Minority AIDS Initiative grants in the Indianapolis-Carmel Metropolitan Statistical Area (MSA). These programs serve the needs of persons newly infected or living with HIV and out of care and/or uninsured or medically underserved.

Revised HIV Case Definition: The Centers for Disease Control and Prevention (CDC) and the Council of State and Territorial Epidemiologists (CSTE) revised HIV surveillance case definitions in 2014.¹ Several changes were made, the most important of which were based on an improved HIV test algorithm that allows for earlier detection of HIV during the acute phase of infection; differentiation of HIV-1 and HIV-2; and, creation of a single case definition for individuals of any age.

Updated HIV Test Algorithm Recommendation: Because a span of approximately three months is necessary to develop a detectable HIV antibody response, the recommended algorithm (Figure 1) calls for test one – the Determine – to be an HIV-1/2 antigen/antibody combination immunoassay (HIV-1/2 ag/ab). This test is able to detect an HIV infection within approximately two weeks post-infection. Test two – the Differentiation – is able to confirm an HIV infection within approximately four weeks post-infection. If an individual has HIV but has not yet developed antibodies (seroconverted), then the Differentiation would be reported as indeterminate. In this instance, a third test is performed. Test three in the new algorithm, if necessary, is a nucleic acid test (NAT). The detection window for this test is only one week post-infection. This test is performed only when the Differentiation is indeterminate due to its cost.

Importance of Early Diagnosis: Delayed linkage and poor engagement in care among people living with HIV has been associated with increased transmission, drug resistance, quicker progression to AIDS, decreased quality of life, and increased mortality.^1,2,3 Use of this testing algorithm moves the window of detection back to only two-weeks allowing for earlier diagnosis, earlier linkage to care, improved health outcomes, and reduced secondary transmission.

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¹ Centers for Disease Control and Prevention & Council of State and Territorial Epidemiologists (2014). Revised surveillance case definition for HIV infection – United States, 2014. MMWR, 63(RR03): 1-10. Retrieved from http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6303a1.htm?s_cid=rr6303a1_e

² Branson, B. M., Handsfield, H. H., Lampe, M. A., Janssen, R. S., Taylor, A. W., Lyss, S. B., and Clark, J. E. (2006). Revised recommendations for HIV testing of adults, adolescents, and pregnant women in health-care settings. MMWR, 55(RR14): 1-17.

³ Gardner, E. M., McLees, M. P., Steiner, J. F., del Rio, C., and Burman, W. J. (2011). The spectrum of engagement in HIV care and its relevance to test-and-treat strategies for prevention of HIV infection. Clin Infect Dis., 52(6): 793-800.

⁴ Centers for Disease Control and Prevention. (2011). Vital signs: HIV prevention through care and treatment – United States. MMWR, 60(47):1621.

⁵ Centers for Disease Control and Prevention & Association of Public Health Laboratories. (2014). Laboratory testing for the diagnosis of HIV infection: Updated recommendations. Retrieved from http://stacks.cdc.gov/view/cdc/23447