In March 2014, Mid America Clinical Laboratories adopted the CDC recommended HIV testing algorithm guidelines. Members of the Panel on Antiretroviral Therapy and Medical Management of HIV-Infected Children recently reviewed the guidelines for Pediatric HIV Infection. The panel suggests that HIV infection can be definitively diagnosed through use of virologic assays in most non-breastfed HIV-exposed infants by age 1 month and in virtually all infected infants by age 4 months. Tests for antibodies to HIV, do not establish the presence of HIV infection in infants due to transplacental transfer of maternal antibodies to HIV; therefore a virologic test should be used.1,2 Positive virologic tests (i.e., nucleic acid amplification tests[NAT]) indicate likely HIV infection. The initial positive biologic test results should be confirmed as soon as possible by a repeat virologic test on a second specimen because false-positive results can occur with both RNA and DNA assays.
The new testing algorithm put in place at MACL begins with a “fourth-generation” combination immunoassay that detects both HIV p24 antigen and HIV antibodies. The manufacturer has established performance for individuals younger than 2 years. Nearly all infants born to HIV-infected mothers passively acquire maternal antibody and, in some cases, will test antibody positive until age 18 months regardless of whether they are infected. Definitive diagnosis of HIV infection in early infancy requires other assays including HIV nucleic acid tests or viral culture.3
MACL will test all patient samples regardless of the patient’s age. The test’s limitations expressed by the manufacturer are included with the results.
1. European Collaborative Study. Age-related standards for T lymphocyte subsets based on uninfected children born to human immunodeficiency virus 1-infected women. The European Collaborative Study. Pediatr Infect Dis J. Dec 1992;11(12):1018-1026. Available at http://www.ncbi.nlm.nih.gov/pubmed/1361051.
2. Shearer WT, Rosenblatt HM, Gelman RS, et al. Lymphocyte subsets in healthy children from birth through 18 years of age: the Pediatric AIDS Clinical Trials Group P1009 study. J Allergy Clin Immunol. Nov 2003;112(5):973-980. Available at http://www.ncbi.nlm.nih.gov/pubmed/14610491.
4. Alere Determine™ HIV-1/2 Ag/Ab Combo Package Insert. 2013