Reasons you may not be able to
have the test or why the results may not be helpful include taking antiviral
What To Think About
Sometimes positive antibody or antigen
detection test results are made by organisms other than the virus. This is
called cross-reactivity, which leads to a
false-positive test result. A test that shows a viral
infection may need to be confirmed by additional tests.
an unborn baby (fetus) or newborn baby is tested for several viral
infections all at the same time. This is called a TORCH test (for
toxoplasmosis, other infections,
herpes). The TORCH test shows whether a fetus or
newborn is likely to have any of these infections.
Depending on the
virus, it can take weeks for antibodies to develop after exposure to the virus.
In these cases, test results may be negative early in the course of the
infection. This is called a false-negative test result. Another blood sample
may need to be drawn later to check again for the viral infection. Antibody
titers that get higher over 3 weeks from the first sample to the second usually mean
the infection occurred recently.
Tests are available that can
identify many viruses from one sample of body fluid. For example, one test can
identify 12 different viruses that may be causing a lung
Spinal fluid is collected during a spinal tap (lumbar
puncture). For more information, see the topic
For more information on
specific tests, see the following topics: