Some people with chronic fatigue syndrome do, in fact, have high levels of antibodies to the Epstein-Barr virus, indicating they had experienced a previous infection with it and perhaps recurrent infections as well. But other people with the syndrome have normal or no antibodies to the virus, so that Epstein-Barr virus may not be that important after all. Other evidence that the Epstein-Barr virus is not directly linked to chronic fatigue syndrome comes from studies with a drug called acyclovir, which blocks the virus' multiplication. Patients with chronic fatigue syndrome treated with the drug did not show significant improvement compared to those given a placebo. Another common factor in chronic fatigue syndrome is allergy.
Patients have twice the number of allergic skin reactions as people without the illness.
We don't know why this is so, but this information may indicate that the patients may be overly sensitive to certain agents. Such extra sensitivity may predispose the patients to infections or other types of abnormal reactions to foreign substances and might account for the syndrome. Several studies have revealed that certain components of the immune system behave abnormally. For example, chemicals called interleukin-2 and gamma interferon, which the body produces during its battle against cancer and infectious agents, may not be made in normal amounts. Even though these chemicals do not seem to be made normally, there is evidence that a low-grade battle is being waged by the immune system of CFS patients.