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Introduction ⬇

There are two main strains of HIV: HIV-1 and HIV-2. Infection with HIV-1 is more common worldwide and is more likely to progress and worsen. HIV-2 is found predominately in West Africa with slower progression than HIV-1, with many remaining lifelong nonprogressors. HIV-1 p24 antigen is a viral protein that is present in high amounts in individuals who are newly infected. A combination immunoassay is used to detect HIV-1 and HIV-2 antibodies, as well as HIV-1 p24 antigen (referred to as fourth-generation testing). If a specimen is reactive on the initial immunoassay, then additional testing will take place to differentiate between HIV-1 and HIV-2 antibodies.

If the results of the additional testing are either nonreactive or indeterminate, then HIV-1 nucleic acid testing (NAT) will be done. This test process provides the foundation for identifying acute and established HIV-1 infections, providing more accurate diagnosis of HIV-2 infection and timely reporting of test results to public health entities. After identification and differentiation of HIV-1 and HIV-2 antibodies, additional tests such as HIV-1 viral load, CD4+T-lymphocyte, and antiretroviral resistance assay are necessary to confirm infection, determine the stage of HIV disease, and tailor treatment (Table 8.9). Most cases associated with HIV-2 are reported in West Africa.

Normal Findings ⬆ ⬇

Procedure ⬆ ⬇

Serum Testing

  1. Use a special testing kit such as the Food and Drug Administration–approved commercial Alere Determine HIV-1/2 Ag/Ab Combo. The kit includes a specially treated sample pad, to which a whole blood (from venipuncture or fingerstick), serum or plasma specimen is applied. A chase buffer is applied to whole blood samples, and the test results are read between 20 and 30 minutes after application of the chase buffer.

  2. Interpret the results according to the manufacturer’s guidelines and instructions.

Clinical Implications ⬆ ⬇

  1. An antibody reactive test is associated with the detection of HIV-1 or HIV-2 antibodies in the specimen, and an antigen reactive test is associated with the detection of HIV-1 p24 antigen in the specimen.

  2. The presence of HIV-1/2 antibodies or HIV-1 p24 antigen is presumptive for HIV infection.

  3. A nonreactive test result does not preclude the possibility of an HIV exposure or infection.

  4. Reactive test results should be followed by further confirmatory testing.

  5. An HIV infection is described as a continuum of stages that range from the acute, transient, mononucleosis-like syndrome associated with seroconversion to HIV infection without symptoms to HIV infection with symptoms and, finally, to HIV/AIDS, which is end-stage HIV infection.

  6. Treatments are more effective and less toxic when begun early in the course of HIV infection.

Interventions ⬆ ⬇

Pretest Patient Care

  1. An informed, witnessed consent form must be properly signed by any person being tested for HIV/AIDS. This consent form must accompany the patient and the specimen (see Appendix F for sample form).

  2. It is essential that counseling precedes and follows the HIV test. This test should not be performed without the subject’s informed consent, and persons who need to access results legitimately must be mentioned. Discussion of the clinical and behavioral implications derived from the test results should address the accuracy of the test and should encourage behavioral modifications (e.g., sexual contact, shared needles, blood transfusions).

  3. Assess frequency and intensity of symptoms: elevated temperature, anxiety, fear, diarrhea, neuropathy, nausea and vomiting, depression, and fatigue.

  4. Infection control measures mandate use of standard precautions (see Appendix A).

  5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Clinical Alert

  1. Issues of confidentiality surround HIV testing. Access to test results should be given judiciously on a need-to-know basis unless the patient specifically expresses otherwise. Interventions to block general computer access to this information are necessary; each healthcare facility must determine how best to accomplish this.

  2. Conversely, healthcare workers directly involved with the care of an HIV/AIDS patient have a right to know the diagnosis so that they may protect themselves from exposure.

  3. All results, both positive and negative, must be entered in the patient’s healthcare records while maintaining confidentiality. People are more likely to test voluntarily when they trust that inappropriate disclosure of HIV testing information will not occur.

  4. The healthcare provider must sign a legal form stating that the patient has been informed regarding test risks.

  5. A person who exhibits HIV antibodies is presumed to be HIV infected; appropriate counseling, medical evaluation, and healthcare interventions should be discussed and instituted.

  6. Positive test results must be reported to the state and federal public health authorities according to prescribed state regulations and protocols.

  7. Anonymous testing and reporting is available, such as commercial home tests.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. Explain significance of test results along with CD4+ cell counts. Provide options for immediate counseling if necessary.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. Test kits require the use of specific specimens. Refer to test kit instructions to verify that the proper specimen type is being used; otherwise, the kit may produce inaccurate results. Timing of appearance of viral and serologic markers varies.