Joel E. Gallant, M.D., M.P.H.
Provider Initiated Counselling and Testing (PICT): HIV testing should be routinely offered to all pts attending sexually transmitted infection (STI) services, attending antenatal clinics (ANC) and other reproductive health services, and attending TB clinic services, i.e to all pts suspected or diagnosed with TB infection.
- Diagnostic Counselling and Testing: Involves counselling and testing in a clinical setting and should be considered standard of care in following situations: Diagnosing HIV for appropriate TB and HIV management and for pts who present with Sx or signs that could be attributed to HIV.
- HIV Testing within outpatient and inpatient wards may improve uptake and better integrate HIV testing as part of clinical Dx and pt management.
- Voluntary Counselling and Testing (VCT): Client-initiated HIV testing to determine HIV status provided through voluntary counselling and testing and remains critical to effectiveness of HIV prevention.
- Pre-test counselling may be provided either on individual basis or in group settings with individual follow-up.
- However, clients always have the right to "opt out" (decline the test).
- Difference between 'Opt-in' and 'Opt-out':
- Opt-in: HIV test routinely recommended and offered to each pt, and pt explicitly consents to be tested.
- Opt-out: HIV test routinely recommended and provided to each pt and pt informed of his/her right to refuse testing.
- Mandatory HIV Screening: National blood transfusion policy supports mandatory screening for HIV and other blood-borne viruses of all blood that is destined for transfusion or for manufacture of blood products. Mandatory screening of donors required prior to all procedures involving transfer of bodily fluids or body parts, such as but not limited to artificial insemination, corneal grafts and organ transplant. National HIV policy does not support mandatory testing of individuals on public health grounds.
- Confidentiality in HIV Testing: Confidentiality is key concern for clients. It is essential that confidentiality be maintained when conducting HIV testing of any type. All information about the individual should be kept strictly confidential. Careful record management is prerequisite for confidentiality.
- Zambia National Testing Algorithm: Following testing kits recommended: Abbot Determine HIV ½ Test, Uni-Gold HIV Test, and Bioline HIV ½ Test.
- National algorithm is based on serial testing: First test, use Abbot Determine. If Abbot Determine test negative, report as negative. If Abbot Determine test positive, perform second test using Uni-Gold. If Uni-Gold test positive, report as positive. If Uni-Gold test negative, perform 3rd test with Bioline or request client to test 6 weeks later.
- National HIV Counselling and Testing guidelines encourage use of rapid tests so that results provided in timely fashion and can be followed up immediately with first post-test counselling session for both HIV-negative and HIV-positive individuals/couples.
- Quality Assurance: Quality assurance is important consideration in providing HIV testing services.
- Medical Referrals: All HIV+ pts should be referred to ART clinic for care.
- Social Referrals: Consider referral of pts that test positive to other special organisations for psychological, social and spiritual support.These may include PLHA support groups, religious circles, etc.
- PICT in integrated TB and HIV programs has been successfully implemented in Zambia and resulted in increased proportions of HIV-TB co-infected patients being identified and accessing HIV care.
- Community-based programs to promote couples VCT using leaders from health, religious, non-governmental, and private sectors have been successfully implemented in Zambia.
Zambia Information Author: Larry William Chang, MD, MPH
- Diagnosis of acute or chronic HIV infection
- CDC now recommends routine, voluntary testing of all adolescents and adults without written informed consent. Annual testing recommended for those at high risk. "Opt-out" approach recommended: pt told that HIV testing will be performed, and given opportunity to refuse. Not all state laws allow implementation of these recommendations.
- When routine testing not performed, consider testing for patient request, pts at risk, conditions suggesting impaired cellular immunity (OIs, thrush, recurrent or refractory vaginal candidiasis, recurrent pneumonia, etc.), TB, shingles (especially in young adults), sexually transmitted diseases, pregnant women, hospitalized adults in areas of high seroprevalence
- Enzyme-linked immunoassay (EIA) plus confirmatory Western blot (WB) if EIA repeatedly reactive
- Sensitivity 99.5% after 3 mos of infection; specificity >99.994%
- EIA alone: 2% false positive
- WB: negative = "no" bands; positive = "gp120/160" + either gp41 or p24; indeterminate: any other band pattern
- WB false-positives: Rare. Causes include autoantibodies, HIV vaccines, technical/clerical error.
- WB indeterminate: Causes include seroconversion (especially with p24), cross-reacting antibodies, infection with type O or HIV-2, HIV vaccines
- False negative serology: usually due to testing window period before seroconversion. Rate = 0.3% in high-prevalence population; <0.001% in low-prevalence population. Other rare causes of false-negatives: seroreversion, atypical host response, agammaglobulinemia, infection with type N, O or HIV-2, technical or clerical error.
- False positive serology: frequency 0.0004-0.0007%. Causes: HIV vaccine, factitious HIV infection, influenza vaccination, technical or clerical error
- Indeterminate serology: causes include testing in window period during seroconversion, late-stage HIV infection, cross-reacting non-specific antibodies, infection with type O or HIV-2, HIV vaccination, technical or clerical error. Perform risk assessment and measure VL. If seroconverting, VL usually high and WB positive within 1 month.
Acute HIV infection: Expect negative or indeterminate serology with high VL.
Home Access Express Test: blood test, with results by phone in 3-7 days. Double EIA with confirmatory IFA. Sensitivity & specificity >99% (800-448-8378 or http://www.homeaccess.com/)
OraQuick (OraSure Technologies): HIV-1 & -2 antibody test (blood, plasma, oral fluid). Results read by provider in 20 mins. Sensitivity 100% (blood), 99.6% (oral fluid); specificity >99.5%. CLIA waived.
Reveal G2 (MedMira Inc.): HIV-1 antibody test (serum or plasma, centrifuge required). Sensitivity 99.8%, specificity 98.6%. Not CLIA waived.
Uni-Gold Recombigen (Trinity Biotech): HIV-1 antibody test (blood, plasma, serum). Sensitivity 100%, specificity 99.7%.CLIA waived.
Multispot (Bio-Rad Labs): HIV-1 & -2 antibody test (serum, centrifuge required). Sensitivity 100%, specificity 99.9%. Not CLIA waived.
Clearview (Inverness Medical): HIV-1 & -2 antibody test (blood). Sensitivity 99.7%, specificity 99.9%. CLIA waived.
VITROS (Ortho Clinical Diagnostics): HIV-1 & -2 antibody test (serum, centrifuge required). Sensitivity 100%, specificity 99.5%. Not CLIA waived.
OraSure (OraSure Technologies): Ab screen by ELISA with WB confirmation using oral mucosal collection device. Results in 3 days. Sensitivity >99.2%, specificity >99.8%.
OraQuick (OraSure Technologies): See "Rapid Tests" above.
Calypte HIV-1 Urine EIA (Calypte Biomedical Corp). EIA only: positive results must be confirmed by serology. Sensitivity 99%, specificity 94%.
- Preferred for Dx of acute retroviral syndrome (ARS). Serology preferred in asymptomatic patients, as some HIV+ pts have undetectable virus. May be helpful with indeterminate serology.
- Quantitative HIV RNA (viral load): high levels of viremia with ARS. Low-levels (<10,000) may be false-positive. Rare false-negatives in chronic infection.
- HIV DNA PCR: Qualitative assay to detect cell-associated proviral DNA. May be useful for detection of HIV infection in neonates. Sensitivity >99%. Not FDA approved, and requires confirmation.
- p24 antigen: Less expensive but less sensitive (90%) than HIV RNA for Dx of ARS.
- PBMC Cx: Expensive and labor-intensive. Can be quantitative or qualitative. Sensitivity 95-100%
Aptima (GenProbeInc.): Qualitative HIV-1 RNA: Approved for Dx of HIV infection, including acute or primary infection, and to confirm Dx in pt with repeatedly positive serology. Advantages over viral load testing unclear.