Most people recover from infectious diseases without further consequences. Others feel exhausted and sick for weeks or months. Such conditions have recently been in the limelight, mainly due to Corona. One speaks of post-Covid syndrome when the symptoms last more than twelve weeks. This might affect around two percent of all those suffering from Covid-19as the German Society for Pneumology and Respiratory Medicine (DGP) estimates.
“Long-term consequences of infections have been known for many years,” says a statement from the Berlin Charité. “They have hardly been researched.” They can lead to a “serious, mostly lifelong illness with varying degrees of physical and mental symptoms”, which has also only been little researched in Germany. One speaks of chronic fatigue syndrome ME/CFS, a long-term neuroimmunological disease.
One new Berlin study now showsthat some of the Covid-19 sufferers can actually develop the full picture of ME/CFS disease even following a mild course. A team of researchers examined 42 people at the Charité who were still suffering from severe exhaustion and limited resilience in everyday life at least six months following their corona infection. “Most of them might only do light work for two to four hours a day, some were unable to work and might hardly look following themselves,” says the statement from the Berlin Charité and the Max Delbrück Center for Molecular Medicine (MDC ).
Two groups with different levels of “exertion intolerance”
Of the 42 people affected, three had gone to a hospital because of Covid-19 but did not need oxygen. According to the WHO classification, 32 were only “mildly” ill and had mostly had stronger symptoms, but no pneumonia. Nobody was vaccinated because the diseases affected the first wave of the 2020 pandemic.
About half of the 42 subjects developed full-blown ME/CFS. The other half also suffered from “greatly reduced resilience”. In her case, however, the core symptom of ME/CFS was not so pronounced: the so-called post-exertional malaise (PEM) or “stress intolerance”, often called “crashes” by those affected.
What is meant is that the disease worsens following even minor physical or mental stress, such as going shopping, going for a walk, having a conversation, reading or taking a shower. This often happens with a time delay of up to 48 hours following exposure. “Crashes” might last for days, weeks, months or, in the worst case, permanently, writes the German Society for ME/CFS. If the course is severe, even turning over in bed can lead to a “crash”.
The scientists found two groups – with different levels of “exertion intolerance”. They carried out further investigations, for example comparing the strength of the muscles using hand strength measurements and determining the various laboratory values. In the group with the less pronounced “crashes” they suspect “a persistent inflammatory reaction” as the cause of their symptoms. Because they measured an increased level of the immune messenger substance interleukin-8 there.
In the group who suffered full-blown ME/CFS, they suggest that “reduced blood flow may be responsible for the muscle weakness.” Because they measured a certain hormone that is released by muscle cells when the oxygen supply is too poor.
New network IMMME wants to track down the causes
The difference between the two groups might also be reflected in the course of the disease. “In many people who have ME/CFS-like symptoms but do not develop the full picture of the disease, the symptoms seem to improve over the long term,” said Carmen Scheibenbogen, acting director of the Institute for Medical Immunology at the Charité and one of the heads of the Study. The data provided “further evidence that ME/CFS is not a psychosomatic disease, but a serious physical disease that can be recorded using objective examination methods,” says Scheibenbogen.
So far, there has been no clear diagnosis and no therapy for ME/CFS, although experts estimate that around 300,000 people in Germany were affected before the pandemic began, around 40,000 of them under the age of 18. “About half of the predominantly younger and female patients are so ill that they can no longer work,” says the Charité. “Those who are most severely affected are bedridden and no longer able to look following themselves.” The most common symptoms included weakness and exhaustion (fatigue), muscle aches and headaches, intestinal problems, dizziness, sensitivity to stress and irritation, tachycardia and fluctuations in blood pressure.
So how can ME/CFS develop? A new research network led by the Charité wants to track down the mechanisms. It is called IMMME (IMune Mechanism of ME). In addition to the Charité, it also includes scientists from Lübeck, Bonn, Würzburg and Munich. It will be funded by the Federal Ministry of Research with around two million euros over the next three years.
Biomarkers should help doctors with the diagnosis
In the majority of patients, the disease begins following an infection, for example with herpes viruses such as the Epstein-Barr virus, with dengue or influenza viruses. According to the Charité, some of the patients had already developed ME/CFS during the Sars pandemic of 2002 and 2003. “The latest studies point to autoimmune processes and a dysregulation of the autonomic nervous system and cellular energy metabolism,” writes the Charité. But there were still no reliable biomarkers, i.e. measurable values in blood or serum that can be used to diagnose the disease. The scientists of the IMMME network want to change that.
Autoantibodies, which contribute to the control of important processes in healthy people, are said to play a decisive role in the development of ME/CFS. After infection, they can change their function and lead to the development of autoimmune diseases. In the case of ME/CFS, the scientists working with Carmen Scheibenbogen already have certain autoantibodies in mind.
According to Charité, their hypothesis is: “Some of the autoantibodies have changed their structure and bind to certain receptors in such a way that incorrect information in the cells leads to malfunctions in immunological, regulatory or metabolic processes.” In five sub-projects, the IMMME researchers now want to investigate what exactly what happens here – at the molecular level.
For the first time, a systematic, comprehensive basis for diagnostic markers should be created. “In particular, the researchers hope that it will be possible to identify structures that serve as the basis for targeted therapeutic approaches to the autoimmune disease,” writes the Charité. This is what ME/CFS sufferers have been hoping for for a long time.
