The basic principle behind an HIV rapid
immuno-chromatographic test is that
HIV-antigens placed on the test-strip will
react with Anti-HIV antibodies (if there
are any) from the blood. That reaction
becomes visible as a colored line next to
the control line. The reaction between
antigens and antibodies (if there are any)
requires 5-15 minutes to become visible
depending upon the concentration of the
antibodies in the blood (if present).
However, if the test does not show a
control line, the result is not valid.
The producers of the IV rapid
immuno-chromatographic test say that the
resulting interpretation after 20 minutes
is also not valid unless the room
temperature is under 15oC. In your case
the test result after 20 min. was negative
but became “positive” after 7 hours.
That “positive” result is not valid.
Your test result was NEGATIVE.
I assume that the reason the test results
are not valid after 20 minutes is that
after time, another factor in the the
blood can precipitate and create a line
that can be similar to the line created by
antibody-antigen reaction. Further, the
line created by an antibody-antigen
reaction can also disappear in time
because links between antigens and
antibodies can get weak. But this
hypothesis has not been confirmed by the
manufacturers.
hiv rapid immunocromatographic test result
- why is there a time limit?
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