Most ME/CFS specialists seem to use antibody tests (which measure the immune response to a virus) rather than blood PCR tests (which tries to directly detect the virus in the blood).
This is because you often do not find viruses in the blood in ME/CFS; they are instead found in the tissues. Dr Dantini for example thinks that blood PCR tests are of no use for herpesvirus testing in the case of ME/CFS.
Dr John Chia found that in ME/CFS patients with chronic enterovirus infections, even the most sensitive blood PCR tests would only detect these infections in around 1 in 3 patients, and so 2 in 3 patients would get a false negative result from this blood PCR test.
Whereas the enterovirus (coxsackievirus B and echovirus) antibody tests performed at ARUP Lab using the neutralization method proved reliable (other methods of enterovirus antibody testing like ELISA, IFA and CFT are not that reliable). The Hellenic Pasteur Institute in Greece also offer coxsackievirus B antibody tests by neutralization at a very good price.
I wrote to the lab director of RedLabs explaining this issue about blood PCR testing in ME/CFS, and asking why RedLabs offered PCR tests when most ME/CFS doctors use antibody tests. But he did not seem to want to engage in much discussion.
Some ME/CFS doctors like Dr Peterson will use PCR on cerebrospinal fluid from a lumbar puncture; I am not sure of how reliable this is. So generally ME/CFS doctors use antibody tests.
But you need an ME/CFS doctor to interpret your antibody test results. If your antibody titers are high enough, you will be diagnosed with a chronic active infection. But that diagnosis requires an ME/CFS doctor's expertise.
Dr Daniel Dantini diagnoses a chronic active infection in ME/CFS patients when IgG antibody titers are at least
4 times higher than the average IgG titers that a group of healthy people would get on the same test. Ref:
here. Having higher than average titers is the way most ME/CFS doctors diagnose chronic active infection.
So unless you know what the average titers are for a particular test, it is hard to know whether you have a chronic active infection or not. You will not find this information on your test results.
Regular infectious disease specialists will often ignore the high IgG titers frequently found in ME/CFS patients, interpreting such high titers as just a past infection (which is why going to see an infectious disease doctor is usually of little help in the case of ME/CFS).
Whereas ME/CFS specialist doctors interpret these high titers as evidence of a chronic active infection, and will then treat with appropriate antivirals or immunomodulators (which
published studies have shown can make major improvements).