Onset of ME/CFS

The onset of ME/CFS can be sudden (acute) or gradual. Sudden onset is more common. Dr. Melvin Ramsay and Dr. Byron Hyde both describe sudden and acute onsets for myalgic encephalomyelitis (ME) as oppose to ME/CFS being acute or gradual. In cases of sudden onset, it is usually easy to identify the trigger of the illness, such as physical trauma, overwhelming stress, or a viral/bacterial infection. Children, particularly adolescents, will more likely have an acute illness like the flu or mononucleosis as their onset.

Genes are being considered for a risk in developing ME/CFS as sometimes several members of the same family will develop ME/CFS.

Pre-onset triggers
The International Consensus Criteria Primer includes a patient assessment form, which includes factors that may have triggered ME, these can be infectious (for example, a virus), or non-infectious (for example, exposure to chemical toxins or severe physical injury).

Infectious exposure or events

 * minor infections, vaccination, upper respiratory infections, sinusitis, pneumonia, gastrointestinal illness (after sinusitis or pneumonia), dental infections, vaginal infection, cystitis, prostatitis, blood transfusion
 * exposure to: sick people, unfamiliar infectious agents when travelling, particularly following vaccinations, contaminated water, poor quality recycled air

Non-infectious exposure or events
Other triggers have been recognized besides these.
 * exposure to: chemical toxins, heavy metals, or moulds
 * severe physical trauma e.g. whiplash/spinal injury/surgery
 * anaesthetics
 * undue stress
 * steroids

Some ME patient charities, for example The Hummingbirds' Foundation for ME hold the view that ME is always caused by a virus, but chronic fatigue syndrome may have non-viral triggers, and do not recognize bacterial infections or non-infectious events as a potential cause or trigger.

Is ME always caused by a virus
Some ME patient charities, for example The Hummingbirds' Foundation for ME hold the view that ME is always caused by a virus, but chronic fatigue syndrome may have non-viral triggers, and do not recognize bacterial infections or non-infectious events as a potential cause or trigger. The onset events recognized as potential causes or triggers in the International Consensus Criteria are based on events prior to illness that have been reported by patients meeting the diagnostic criteria for Myalgic Encephalomyelitis. The exact cause has not yet been identified in research. Chu et al. (2019) reported on pre-onset events for patients meeting the chronic fatigue syndrome Fukuda criteria only.

Development of ME
The International Consensus Criteria recognizes that myalgic encephalomyelitis can develop
 * suddenly
 * gradually, or
 * be infectious (for example, outbreaks within a community)

Criteria

 * In the Holmes criteria, description of the main symptom complex as initially developing over a few hours to a few days is an optional criteria for diagnosis, under the section Minor Symptom Criteria.

Notable studies

 * 2019, Onset patterns and course of myalgic encephalomyelitis/chronic fatigue syndrome (Full text)

Learn more

 * Presentation and Clinical Course of ME/CFS
 * 2018, Onset patterns of chronic fatigue syndrome and myalgic encephalomyelitis