1. b. All positive results of the HIV rapid test require a confirmatory Western blot or immunofluorescent assay (IFA). An HIV EIA is not required, but if it is performed and the results are negative, a confirmatory test is still required. For persons with a negative or indeterminate confirmatory test result, follow-up HIV testing should be repeated 4 weeks after the initial positive rapid HIV test result.

Before a rapid test is performed, patients should be counseled that they will receive the results at the same visit and, if positive, the meaning of a preliminary positive result. In the event of a positive rapid HIV test result, the provider should emphasize the importance of confirmatory testing. Providers should collect blood or saliva for the confirmatory test at the same visit and schedule an appointment for results of the confirmatory test. In 2006, the Food and Drug Administration (FDA) approved a new test, Aptima, for the diagnosis of primary HIV-1 infection as well as for confirmation of HIV-1 infection when tests for antibodies to HIV-1 are positive. Aptima is a qualitative nucleic acid test that detects the RNA of HIV-1 and may be used as an alternative to the Western blot for confirmation. Aptima may be helpful for diagnosis of early HIV-1 infections before antibodies have developed as well as in cases in which the Western blot is indeterminate. Consideration may be given as well for assessment of HIV proviral DNA.

The patient in Clinical Case Problem 1 should be counseled about the chance that her positive HIV rapid test result could be a false positive as well as about risk reduction behaviors while awaiting the results of the Western blot. The patient and her husband had confirmatory HIV tests performed, and the results of both were negative, including a repeated HIV test performed 4   weeks later.

2. b. Rapid HIV tests are an important tool to assess for early HIV infection in high-prevalence areas for high-risk individuals and for women in labor and delivery as well as in other nontraditional or high-risk settings. Rapid HIV tests have also been employed in emergency departments, inpatient hospital settings, and correctional facilities and for occupational exposures. In 2000, the CDC estimated that 31% of individuals who tested at a public sector testing site did not return for HIV test results.

Four rapid HIV tests have been approved by the FDA and share many common features. In all of these tests, HIV antigens are affixed to the test membrane or test strip. If the patient has HIV antibodies present, the antibodies will bind to the affixed HIV antigens. No instrumentation is required for these tests, and the tests are interpreted by visual inspection. When used according to the manufacturer’s guidelines, these tests range in sensitivity from 99.3% to 100% and in specificity from 98.6% to 99.9% and are similar to HIV EIA. False-positive results are known to occur (testing is designed to have greater sensitivity than specificity) and are measured by the positive predictive value (PPV), which is the probability that the patient has the disease if the test result is positive. PPV will decrease if the prevalence of HIV infection is low (less than 0.1% population prevalence) and increase if the prevalence of HIV infection is high (0.2% to 0.3% population prevalence). All positive rapid HIV tests require confirmatory Western blot or IFA. However, a negative rapid HIV test result does not require confirmation. False-negative rapid HIV test results occur rarely and may be seen during evolution of acute HIV infection and before HIV antibodies have developed. Individuals with HIV exposure within 3   months prior should be instructed to retest at 6, 12, and 24   weeks after HIV exposure.

3. c. According to the CDC guidelines, all persons between the ages of 13 and 64   years should be screened for HIV infection as part of routine clinical care unless HIV prevalence has been documented to be less than 0.1%. Patients seeking care for treatment of sexually transmitted diseases as well as patients initiating TB treatment should also receive an HIV test without consideration for prevalence. Annual HIV testing should be performed for all individuals with high-risk behavior for HIV infection; these include injection drug users and their partners, persons who exchange sex for drugs or money, men who have sex with men, and heterosexuals who have had more than one partner since their last HIV test.

4. e. In 2006, the CDC published new guidelines for HIV testing. The reasons for the new guidelines were to increase screening and early detection of HIV infection, to link HIV-infected patients to earlier care and prevention, and to reduce perinatal transmission. One rationale for implementing these new guidelines is the changing demographics of HIV-positive individuals. The rate of HIV infection is increasing in adolescents (15- to 24-year-olds), adults (50- to 64-year-olds), heterosexual men and women, members of racial and ethnic minorities, and individuals who live outside of metropolitan areas. Other reasons for the new HIV testing guidelines include prior success with universal testing of the blood supply and routine HIV testing in perinatal clinics. However, reduction in sexual transmission of HIV infection has been disappointing throughout the years, and it is in fact increasing in recent years. HIV-unknown individuals account for a disproportionate rate of sexual transmission compared with HIV-positive individuals who are aware of their diagnosis. Transmission has various mechanisms that are different by locale and region of the country. According to a meta-analysis of eight studies, HIV-positive individuals have been shown to reduce unprotected vaginal or anal intercourse by an average of 68%.

The CDC guidelines (2006) recommended HIV opt-out testing. Patients must be counseled in writing or verbally that an HIV test is planned and agree to the test. Oral and written material should be provided regarding the meaning of a positive and a negative HIV test result, and the patient should have an opportunity to ask questions. A signed HIV consent is no longer encouraged or recommended by the CDC. For patients declining the HIV test, documentation of the refusal should be recorded. Informed consent for an HIV test is no longer a recommendation by the CDC, but many states have legislation that requires informed consent. Some states are working on legislation to reconcile the differences between the CDC recommendations and current legislation. These issues are changing annually, dependent on regional legislative activity.

5. e. Initial laboratory evaluation of a new HIV-positive patient should include an HIV antibody test (if one is not available), CD4 T-lymphocyte cell count, plasma HIV RNA, complete blood count, chemistry profile, transaminase levels, blood urea nitrogen and creatinine concentrations, urinalysis, rapid plasma reagin or VDRL test, TST (unless there is a history of prior tuberculosis or positive skin test response), T. gondii IgG, hepatitis serologies (A, B, and C), and cervical Pap smear in women and anal Pap smear for men as well as other STD assessment. A genotype is preferred to evaluate the treatment-naive patient as presented here (or patients with early virologic failure or patients no longer receiving therapy). The CD4 T-lymphocyte cell count is part of the HIV staging system and identifies those patients at higher risk for life-threatening opportunistic infections (less than 200). Prophylaxis for opportunistic infections is based on results of the CD4 T-lymphocyte cell count. HIV RNA and T-cell counts have been shown to be prognostic indicators of HIV disease progression and are used to monitor response to ARV (HAART) medications. Fasting blood glucose and lipid levels are recommended for those at risk for cardiovascular disease and for baseline evaluation before initiation of ARV medications (especially protease inhibitors).

The HIV genotype test has become part of the initial HIV evaluation since transmission of HIV-resistant virus has been documented, occurs more frequently, and is associated with suboptimal response to initial ARV medication selection for presumed “wild type.” The genotype assays detect mutations in the reverse transcriptase and protease portions of the genome. These mutations predict resistance to specific antiretroviral drugs and can guide selection of initial HAART. HIV genotype tests should be performed for those with HIV RNA of more than 1000 copies/mL, even if ARV therapy will be deferred. (For severe cases of acute seroconversion reaction, empirical therapy may be considered and revised appropriately if necessary on receipt of laboratory results.) HIV genotyping should not be performed for those individuals with HIV RNA of less than 1000 copies/mL because amplification of the virus is unreliable. The International AIDS Society–USA maintains a list of significant resistance-associated mutations that can be reviewed at www.iasusa.org. The cryptococcal antigen test is a latex agglutination test that measures cryptococcal polysaccharide antigen and should be reserved for symptomatic patients.

6. c. ARV medications should be initiated for any HIV-positive person with any AIDS-defining illness or severe symptoms of HIV infection regardless of CD4 T-lymphocyte cell count or for any asymptomatic HIV-positive person with a CD4 T-lymphocyte cell count of less than 200 cells/mL. Current evidence suggests initiation of HAART independent of consideration of T-cell count (i.e., HIV virus = initiation of treatment). There is strong evidence of improved survival and reduced disease progression in this group of individuals. ARV medication should be offered to asymptomatic HIV-positive persons with a CD4 T-lymphocyte cell count of 201 to 350 cells/mL. The optimal time to begin ARV medications is as yet not fully known, but most specialists recommend beginning ARV therapy in HIV-positive persons with a CD4 T-lymphocyte cell count of 201 to 350 cells/mL at the least on the basis of criteria for the risk of disease progression as determined by observational cohorts. For asymptomatic HIV-positive persons with a CD4 T-lymphocyte cell count higher than 350 cells/mL and HIV RNA of more than 100,000 copies/mL, most clinicians have in the past deferred therapy; however, it is important to understand that this issue is in rapid and current flux, and it is necessary to individualize the decision to start ARV therapy because each situation is different. (Clinical tolerance to HIV infection is highly variable, from patients with exquisite and severe early conversion reactions to prompt AIDS to those who are “elite nonprogressors” who have been well for years or decades without treatment.)

Recurrent bacterial pneumonia is one of the AIDS-defining opportunistic infections and would be a hard indication to begin HAART regardless of T-cell criteria. In addition, the patient under consideration in the question has a CD4 T-lymphocyte cell count of 30, which strongly meets criteria to begin HAART as soon as realistically possible.

7. e. Oral thrush, aseptic meningitis, and thrombocytopenia may be examples of symptomatic HIV infection but are not AIDS-defining diagnoses. Other examples of symptomatic HIV infection include vulvovaginal candidiasis, cervical dysplasia, and constitutional symptoms such as fever or diarrhea for more than 1   month and the findings of oral leukoplakia. The AIDS-defining opportunistic infections are as follows:

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