Viral onset hypothesis

The Viral onset hypothesis is a prominent theory as more than half of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) patients report falling ill after an acute viral infection. Many different viruses have been researched as possible etiological agents.

Disease onset
Some think there is a single, novel viral agent as yet undiscovered.

Others think many different viruses can initiate and sustain the disease. Viruses linked to disease onset include herpesviruses such as Epstein-Barr virus or HHV-6, enteroviruses such as coxsackie or even influenza (the flu) or a flu-like illness. Many viruses and pathogens have been investigated, with finding being mixed and no particular pathogen found.

There are several hypotheses for how the viral trigger initiates and perpetuates the disease.

Chronic infection
Some think that there may be a low grade, chronic infection whereby the initial virus continues to provoke an immune response, especially in key areas such as the gastrointestinal tract, muscle, and the brain, brain stem, and spinal cord.

Autoimmune disease
Some think that symptoms are caused by an inflammatory process that is triggered by an initial infection and continues even after the initial virus is no longer replicating. It is possible that ME/CFS is an autoimmune response that can be triggered by many different infections.

Viral reactivation
Still others think that an immune deficiency allows otherwise common or benign viruses to replicate.

Dysbiosis
Viral infection may trigger dysbiosis leading to alterations in the immune system and gut-brain axis and causing the symptoms of the disease.

Outbreaks


There have been dozens of reported clusters and outbreaks of ME, which all suggest a role of either a communicable pathogen or in some cases, a toxic agent.