Your letter deserves a more extended reply but I just wanted to
address one of the issues which you raised in your letter and in your
article and that is the concern raised about false positive results to
HIV testing.
I think this is terribly important to clarify. There are 2 tests to identify
HIV antibodies in blood, which is the basis for identifying HIV
infection. For diagnostic testing both tests are always done which
virtually eliminates the risk of false positive tests.
One is the ELISA test, which is very sensitive and may rarely be
falsely positive. The other is the Western Blot test, which is more
specific for HIV antibodies and does not have the problem of false
positives.
The only time the ELISA alone will be used is in seroprevalence
studies when the objective is to determine prevalence in a
population and not diagnosis of an individual, and when therefore
the implications of a rare false positive are not problematic.
In this country any diagnostic testing for HIV (and this includes
testing of women antenatally) both tests will be done (on the same)
sample before a diagnosis is established. If there is any doubt on
the basis of that result, a second sample will be requested before
the diagnosis is established.
In the light of this I think the worry about false positive tests in low
prevalence areas can be allayed. It is important, I think, that the
debate not arouse disquiet when such disquiet is not necessary.
Carolyn Roth
Lecturer in Midwifery
St Bartholomew School of Nursing & Midwifery
City University
Philpot St
London E1 2EA
Tel. 0171 505 5869
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