Chronic fatigue syndrome responds to antiviral therapy

According to an article published in the Journal of Medical Virology, herpesvirus-6 could be a possible cause of chronic fatigue syndrome. Herpesvirus-6 is a common virus as most children come into contact with it by the age of 3 ( the infection is transmitted through saliva). The immune system inactivates it, but during childhood herpesvirus-6 infection may as well cause fever and rash. If infection occurs in a immnucompromised patient, then herpesvirus-6 can lead to more serious conditions such as encephalitis, neurological dysfunction, pneumonia, organ failure, etc..

Maria Medveczky, professor of molecular medicine at USF Health and the study’s principal investigator, said that the good thing is that their study showed that the neurological symptoms (chronic pain or long-term fatigue) can be improved with antiviral medication. She added that between 15,000 to 20,000 patients diagnosed with chronic fatigue syndrome may benefit from antiviral therapy.

So far there have been discovered 9 types of herpesvirus (herpes simplex viruses 1 and 2, varicella-zoster virus, Epstein-Barr virus, human cytomegalovirus, human herpesvirus 6, human herpesvirus 7, etc.) that cause a number of signs and symptoms . What is interesting is that after the first contact with the virus, it remains dormant or inactive, which means that at some point it may become active (usually in immunosuppression). HHV-6 however is different from other herpesviruses because it integrates its DNA in telomeres (structures at the end of chromosomes).

In addition, unlike other herpesviruses, it seems that latent HHV-6 genome can be passed on to children, a phenomenon called “chromosomally integrated HHV-6” (CIHHV-6). According to previous studies, approximately 0.8% of the population of the United States of America and the UK is CIHHV-6. It should be noted that most of these individuals are healthy but some of them may be less able to defend themselves against other strains of HHV-6; in addition it seems that some of them have chronic fatigue syndrome.

Studies have shown that the prevalence of CIHHV-6 among CFS patients with significant neurological symptoms is over 2%, which is twice more than in the general population. Therefore, researchers have thought to name this  CFS subtype “inherited Human Herpesvirus 6 Syndrome” (IHS). What is interesting is that the study led by Dr. Medveczky showed that in CIHHV-6 patients with CFS, the virus is active, but responds to valganciclovir, an antiviral drug. What it must be mentioned is that viral RNA levels decreased after treatment for 6 weeks with valgacicovir. The researchers stressed that short term treatment of up to 3 weeks had no effect on the level of viral RNA.