Diagnosing the cause of CFS is not as simple as diagnosing diabetes. Finding the responsible infectious
agent(s) has been a true challenge since antibody tests for various infectious agents can only confirm or
exclude prior exposure once the duration of symptoms is beyond 6 months. Antibodies to many of the herpes
viruses (i.e. EBV, CMV and HHV-6) are often elevated due to chronic activation of the immune system initiated
by another virus or different cause, although these viruses could cause similar symptoms of ME/CFS. Early
evaluation (< 3 months) may be more fruitful.
Antibody testing for enteroviruses is meaningful when done by the appropriate method, and correlated to the
initial presentation of infection. Antibody tests for all six Coxsackie viruses type B are available, but
only 5/26 of the Echoviruses can be detected by this type of test. High levels of antibody for enteroviruses
may only mean recent exposure to the virus, although persistent high levels of antibody over 1-2 years are
more supportive of chronic infection.
Repeatedly positive viral DNA or RNA from the blood or tissue biopsies are better, although not absolute
indicators of persistent infection. Most of the patients will not have a clear cause based on above testing,
and the etiology can be assumed on appropriate history and by systematically eliminating other infectious
causes. There are probably many other causes (infectious or non-infections) which are to be discovered and
added to the list of tests to be done as we understand them in the future.
Staining of stomach biopsies from ME/CFS patients clearly demonstrate the presence of viral protein in
the parietal cells (the cells responsible for producing acid), and this observation has been verified by
finding enterovirus RNA and non-destructive viruses in the same biopsies. More information about the
stomach staining test can be found in our diagnostic section. (the immunoperoxidase page).
T lymphocyte count and natural killed cell function (measurements of immune function) may be low but will
not help with determining the type of infectious agent causing the symptoms. This type of testing is still
too crude to help us understand the state of immune dysfunction in our patients. Low gamma globulin level,
including those of subclasses of IgG, are seen a number of ME/CFS patients, which may be a predisposing
factor for persistent infection.