# Mucosal Viruses in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Missing Piece of the Puzzle?

## TL;DR

This paper suggests that viruses in mucosal tissues may play a key role in ME/CFS, a condition with unclear causes and no effective treatment.

## Contribution

The paper highlights mucosal viruses as a novel and underexplored area in understanding ME/CFS pathophysiology.

## Key findings

- Most studies focus on blood, but mucosal sites may be critical for detecting persistent viruses in ME/CFS.
- Emerging evidence shows latent viruses in mucosal tissues may contribute to immune dysregulation and symptoms in ME/CFS.

## Abstract

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic condition without a definitive aetiology, no reliable diagnostic test, and no proven effective treatment. Despite most patients reporting a post-viral onset of illness, findings to date are conflicting on whether a single virus or multiple viral triggers are involved. Most studies to date have focused on detecting viruses in blood and circulating immune cells with relatively few investigating the presence of viruses in mucosal sites. In this review, we propose that this represents a critical gap in understanding the pathophysiology of ME/CFS knowledge, as mucosal tissues are primary entry points for most pathogens and often serve as reservoirs where viruses may persist. Consequently, they represent ideal niches for identifying persistent infections in ME/CFS. Emerging evidence from saliva and other mucosal samples in ME/CFS patients is consistent with this proposal and that latent viruses can persist and periodically reactivate in mucosal tissues from where they can potentially contribute to immune dysregulation, chronic inflammation, and increased symptom severity that defines ME/CFS.