Those conditions had been dismissed and labelled a psychological ailment for many years rather than recognised as a genuine affliction, University of Otago Emeritus Professor Warren Tate said.
Confirmation of the close link between them and Long Covid, and the medical profession’s immediate acceptance of the Long Covid phenomenon, should mean all post viral fatigue syndromes were treated equally, he said.
ME/CFS people had struggled for years to have their disease recognised and diagnosed by clinicians and potentially given consistent treatment.
"Now, because of the focus being given to Long Covid, we have not only the opportunity to create a platform for all clinicians to do the best for Long Covid patients but also for ME/CFS patients," Prof Tate said.
Following the World Health Organisation issuing a clinical case definition of Long Covid — which was almost identical to that of ME/CFS — Prof Tate began a pilot study to compare New Zealand’s first Long Covid patients with other people of a similar age who had post-viral fatigue syndromes.
His initial data sets of people’s immune cells showed they were virtually identical.
"The diseases were overlapping very closely and were well separated from the control subjects," he said.
"This is our first molecular study and my view is that they are very closely related diseases."
Post-viral fatigue syndromes had previously generally affected small groups of people and been regarded as "boutique illnesses", but Long Covid fundamentally altered that perception, Prof Tate said.
"Covid-19, of course, is not a boutique illness, it has affected 500 million people worldwide."
New Zealand, which a year ago had had just 2288 cases of Covid-19, this week passed the one million case milestone.
While factors such as the impact of the Omicron variant and the greater extent of vaccination meant it was uncertain how many of those people who had recently had the virus might eventually develop Long Covid, there would likely be many more cases than had been experienced so far, Prof Tate said.
"About a quarter of the 25,000 New Zealanders with ME/CFS are bed-bound or house-bound, three -quarters live a very fragile life in the community.
"Long Covid will be a similar burden if we get a lot more cases, at the moment because we did so well in the first part of the pandemic and had so few cases of Covid we had a relatively small number of long Covid cases ... the critical thing will be how many Long Covid cases will we get from Omicron or from other new variants?"
Because of their similarities, in principle research into a cure for Long Covid could benefit MC/CFS patients, Prof Tate said.
"What I am trying to do now is understand the overall holistic effects of these diseases on the body, and if we can do that we can hopefully switch their bodies back to the health, healing state."
A further six deaths of people who had Covid-19 were reported in Otago and Southland yesterday.
The deaths were among 28 reported nationally, but 21 of them were reclassified deaths which dated back as long ago as February and March.
A further 744 new cases were reported in the South yesterday, down from the 889 reported on Tuesday.
There were 18 people in southern hospitals yesterday who had Covid-19.
