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Revised
Guidelines for HIV Counseling, Testing and Referral [CDC MMWR
2001;50 RR-19:1] The
CDC's Division of HIV/AIDS Prevention provides this 58 page document
concerning HIV counseling, testing and referral. Highlights include
the following:
- Who should
be tested?
Recommendations for HIV Prevention Counseling, Testing, and
Referral
- Clients
with increased risk and in settings where those risks are
found: MSM, corrections, drug/alcohol programs, shelters,
outreach, STD and TB clinics
- Patients
from populations with >1% HIV prevalence (hospitals with
seroprevalence rates of >1%)
- Patients
from populations with <1% HIV prevalence if: a) symptoms
suggest HIV (FUO, OI without known immunosuppression); b)
other diagnoses suggesting HIV (STD etc.); 3) self reported
high risk, 4) patient requests test
- Selected
populations: 1) all pregnant women; 2) persons with occupational
exposure; 3) persons with known non-occupational exposure
- Characteristics
of the test
This section provides a useful summary of various tests that are
available for detecting HIV, including the routine serology, rapid
test, home collection test, the saliva test and the urine test.
All of these are designed to detect HIV-1 except standard serology,
which detects HIV-1 and 2. All use the enzyme immunoassay (EIA)
for screening and a Western blot (WB) or immunofluorescence assay
(IFA) for confirmation. All are considered definitive except the
urine-based test, the results of which, if positive, should be
confirmed with a blood sample due to reduced specificity of the
Western blot on urine. Most of these tests require 1-2 weeks for
results. The exception is the rapid test, which requires 10-60
minutes. This test is often preferred when determining the need
for post-exposure prophylaxis, for pregnant women who present
in labor, or in settings where the return rate for results is
low. The only rapid test that is currently available and FDA approved
is the SUDS test, which requires an on-site laboratory testing
capacity. However, this report anticipates that the FDA will approve
rapid tests that "could be classified as CLIA waived to avoid
the requirement for on-site laboratory testing" which means
provider-read. These tests show accuracy comparable to standard
HIV serology. Details are provided in the table below:
| Tests
for HIV Detection |
| Test |
Spec |
Time |
Method |
Test Characteristics |
| Standard
serology |
Serum |
1-2
weeks |
EIA
& WB |
Good sensitivity
and specificity. Tests HIV 1&2 |
| Rapid
test |
Serum |
10-60
min. |
EIA
& WB or IFA |
Convenience,
increased receipt of results |
| Home
test |
Dried
blood |
3-7
days |
EIA
& WB or IFA |
Convenience,
privacy, anonymity, community setting |
| Oral
fluid test |
Saliva |
1-2
weeks |
EIA
& WB |
Non-invasive;
outreach settings |
| Urine
test |
Urine |
1-2
weeks |
EIA |
Must confirm
possible non-invasive; outreach settings |
Interpretation
of Tests:
- Positive
tests: False positive tests are rare except in cases of laboratory
error or mislabeling; patients with positive tests and no identifiable
risks should be considered for repeat testing.
- Negative
tests: False negative results can be caused by: 1) Clinical
symptoms of acute HIV infection or late AIDS; 2) Infection with
HIV-2 or HIV-1 group 0 infection; 3) Recent infection.
- Indeterminate
test results: Recommendations are to repeat testing at least
one month later; tests for HIV DNA or RNA are not FDA approved
for diagnostic purposes, but may be used in consultation with
specialists for determining the infection status of persons with
in determinant results.
posted
1/7/2002
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