Someone correct me if I am wrong.
ME existed in other parts of the world. But same illness (seemingly) also got other names: Royal Free Disease, etc., Post Polio Syndrome, etc. In all these cases, there were outbreaks in an area. And, the symptoms were very similar to what is now known in the US as CFS and in UK was known as ME.
ME had particularly criteria.
Now, if someone had those symptoms, but it was not part of an outbreak, in the US, they were diagnosed as neurasthenia.
In Key West, Florida, an outbreak occurred in mid 1980s. It was called "atypical multiple sclerosis." The reason it is now considered possibly what is now called CFS is because the people who got sick had reactivated EB virus. Their symptoms were also similar to what is now called CFS or ME.
So, UK had ME, a term often used. And US used neurosthenia or these other labels, or people misdiagnosed with depression or other mental illness, including hypochondria.
Then there is the outbreak in Lake Tahoe. At the time, again mid 80s, it was thought to possibly be a new pathogen or an outbreak of a previously known pathogen. the two docs there has highly sophisticated medical equipment of the time and people there were rich. So many tests were performed. CDC came and checked it out. They did not associate it with neurosthenia (which was thought to not occur in outbreaks), or ME, or Royal Free Disease, etc. Why, I don't know. So understand, of the other outbreaks that got other names, there had not been such thorough testing.
Since CDC thought it was new, they came up with a new name. They had decided the symptoms couldn't be caused by EB, so they dropped that name. And they couldn't find the cause, but by that time, it started appearing in other parts of the country. So they made up the name. Since they didn't know the cause, they labeled it on the most prominent symptom. At that time, they didn't know if it was virus or psychological or environmental. But the leaning at the CDC at the time was that it was likely psychological. That may explain why they didn't associate it as being ME. But they did look into other possible causes. (many think the CDC's further investigation was half-hearted at best, and heavily influenced by belief that it was psychological. I say it was bias but also arrogance and sexism.)
Many doctors, though, particularly those who specialized in these patients, began to see similarities between the Tahoe disease (whatever name it is called) and other illnesses, ME, neurosthenia, Royal Free Disease and the others. So they began to think that maybe this wasn't a new illness. These started talking with each other, and with others in other countries. So that is when it was seen that the illness labeled CFS was actually same as ME.
But, the government definitions were different. Illness was same, but definitions were different. The CDC definition left out some of the biological abnormalities the ME definition has. Absent the CDC declaring an organic disease, by default, the Tahoe illness (no matter the place it occurred) became a list of symptoms without a known cause. It ruled out people who developed cancer and other recognized illness. This presumption created a classification that included some people that didn't have the symptoms that are defined in the ME classification on the other side of the Atlantic. So even though the Tahoe illness was ME, the CDC created a new "illness" called CFS that included people that may have something totally different from what is called ME.
But, the illness, the Tahoe illness, is the same. Since the new illness, called CFS, has no known cause and nothing biologically abnormal (according to CDC), it became associated with psychological illness. And the term became more popular and doctors in US were diagnosing people based on CDC definition. Some believed it was a new entity, whether it is psychological or organic. Others believed it was just another name for depression, so they would not diagnose someone with CFS, because there is no such separate illness, in their minds. So that is why I say, ME doesn't exist in US. The organic illness of ME as originally defined, was not used in US, that I know of. And since CFS was by default thought to be (undetermined, but the prominent thought) psychological, here in the US, by labels, we didn't have an illness like ME. Basically, the CDC thought the docs in Incline Village (outside of Tahoe) were quacks and the patients had mass hysteria or illness brought on by stress.
And even in more recent years, for survey purposes, CDC has defined CFS even more broadly. So this includes a bunch of people who have fatigue with any of a number of causes. By watering down the definition, the true illness has been lumped in with a bunch of other people. Yet, given the cloud of confusion, doctors here are loath to diagnose someone with CFS, because it doesn't mean anything and there is not drug to fix it, unlike diabetes. So, only 15%, according to CDC, of the people in the US who have CFS actually carry the diagnosis. (given that they defined what CFS is and it may include many who don't have the Tahoe illness, that figure can not be trusted. Likely, of those who carry the Tahoe illness, more of them do carry the diagnosis. But since so many doctors don't even believe CFS is a separate illness, they are putting these patients into the depression diagnosis. So there are still many who have the Tahoe illness that don't have either a CFs or ME diagnosis.)
After CFS became the US term, the UK started to see the association of the same illness. So they started saying ME is CFS. And since CFS is not known to have organic abnormalities, the understanding of ME shifted in UK.
Since ME originally had a clear organic definition and listed as neurological, many people are rejecting the CFS label.They are making a distinction between the two, thinking ME is the Tahoe-like illness, whereas the CFS is the unknown, possibly psychological illness.
So people are classifying themselves based on the original definition of ME. Even though doctors aren't making the distinction. They are trying to revive the clear organic definition of ME, because being told they have CFS creates a misunderstanding of the true nature of their illness. But doctors aren't making the distinction.
In the autopsy of Sophia Mirza, the doctor declared she died of renal failure as a complication of chronic fatigue syndrome. Yet, he was a UK doctor. When asked why he said CFs instead of ME, even though he stated the spinal chord abnormalities, he said it is basically same illness, just CFS is now more known.
Doctors consider them all the same. But patients are trying to make a distinction to rule out those who don't have the organic illness. It's hard to get the right name when there may be many people with similar symptoms but very different causes. The common thought now is to say there are "subsets" of the illness.
This was long, but I hope it helps.
Tina