Although Chronic Fatigue Syndrome (CFS) causes have been studied for nearly 20 years, the exact cause of this painful and debilitating disease is still not known.

According to the Center for Disease Control:

Much of the ongoing research into a cause of CFS has centered on the roles of the immune, endocrine and nervous systems may play in CFS. More recently, interactions among these factors are under evaluation. Genetic and environmental factors may play a role in developing and/or prolonging the illness, although more research is needed to confirm this. CDC is applying cutting-edge genomic and proteomic tools to understand the origins and pathogenesis of CFS.

CFS is not caused by depression, although the two illnesses often coexist, and many patients with CFS have no psychiatric disorder.

Some experts have proposed the theory that CFS might be triggered by virus infection and toxins. Other experts theorize that CFS might be related to stress,overwork,physical inactivity, problems with the immune system, low blood pressure, or hormonal imbalance. It is also possible that Colitis, hypoglycemia and brucellosis could cause chronic fatigue syndrome.

The CFS Internet Group says this about the cause of Chronic Fatigue Syndrome:

"Current theories (about the cause of CFS) are looking at the possibilities of neuroendocrine dysfunction, viruses, environmental toxins, genetic predisposition, or a combination of these. For a time it was thought that Epstein-Barr Virus (EBV), the cause of mononucleosis, might cause CFS but recent research has discounted this idea. The illness seems to prompt a chronic immune reaction in the body, however it is not clear that this is in response to any actual infection -- this may only be a dysfunction of the immune system itself.

"A recent concept promulgated by Prof. Mark Demitrack is that CFS is a generalized condition which may have any of several causes (in the same way that the condition called high blood pressure is not caused by any one single factor). It *is* known that stressors, physical or emotional, seems to make CFS worse.

"Some current research continues to investigate possible viral causes including HHV-6, other herpes viruses, enteroviruses, and retroviruses. Additionally, co-factors (such as genetic predisposition, stress, environment, gender, age, and prior illness) appear to play an important role in the development and course of the illness.

"Many medical observers have noted that CFS seems often to be "triggered" by some stressful event, but in all likelihood the condition was latent beforehand. Some people will appear to get CFS following a viral infection, or a head injury, or surgery, excessive use of antibiotics, or some other traumatic event. Yet it's unlikely that these events on their own could be a primary cause."