Researchers, led by molecular biologists from Cornell University, are revisiting the viral origins of chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME/CFS), in a new paper. Historical evidence suggests that viral infections likely trigger many ME/CFS cases. However, the specific virus responsible remains uncertain.
The umbrella term ME/CFS encompasses a range of disabling symptoms, including muscle pain, brain and spinal cord inflammation, unrelenting fatigue, unrefreshing sleep, and post-exertional malaise. Although ME/CFS is often considered isolating, clusters of cases have been documented in past outbreaks, some coinciding with viral infections.
Researchers estimate that around 67 million people worldwide had ME/CFS as of 2020, with parallels to long COVID becoming apparent during the COVID-19 pandemic. The focus on RNA viruses and their persistence in tissues for extended periods has grown, given the growing recognition of post-viral illnesses.
The paper suggests that enteroviruses, a group of RNA viruses that enter the body through the intestine, might be the most likely culprit of ME/CFS. Persistent enteroviral infections have been detected in people with ME/CFS, but inconclusive results from studies comparing blood and tissue samples have previously hindered research into this link.
Pinning down a viral cause for ME/CFS is challenging, as blood tests can only definitively identify a specific virus during the acute phase of infection. Additionally, people with ME/CFS may not connect their illness to a previous viral infection, and up to half of enteroviral infections are asymptomatic. Modern genetic sampling techniques could help detect residual viruses hiding in cells and tissues.
While enteroviruses are a prime suspect, other viruses like Epstein-Barr (EBV) are also thought to trigger ME/CFS. EBV, like other human herpes viruses, can remain latent in the body for years before reactivation. While viral triggers are regaining attention, other mechanisms, such as malfunctioning mitochondria and low levels of thyroid hormones, are also being explored in understanding the complex condition of ME/CFS. A combination of factors likely contributes to the illness, further complicating efforts to understand and treat it.