Jan Willem Elte, The Netherlands
For many years we know that patients may continue to have complaints long after an acute infection (mostly viral) has vanished. New research now sheds light on some of the problems associated with the post viral syndrome.
Until now no good explanation for these lasting complaints has been found and also no cure. Well-known viral infection diseases such as influenza, Q-fever, Epstein-Barr virus and mononucleosis infectiosa (M.Pfeiffer) have resulted in long-lasting periods of complaints, described as post-viral disease. Nowadays these complaints have been taken together and called myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS).
ME/MFS is a complex, chronic condition influenced by multiple factors and it received its name because despite extensive research no definitive cause or tools with which to diagnose it are available. The condition results in debilitating symptoms with extreme fatigue, unfreshing sleep, difficulty in recovering from exertion, cognitive dysfunction and immune system abnormalities. It may last for years with little or no improvement. Moreover, these complaints are quite frequent and are non-specific. Infections may just be one of the causes and indeed after certain infections some persons experience durable symptoms.
Since the start of the Covid-19 pandemic, infection with SARS-CoV-2 has resulted in long-term debilitating symptoms in many people known as long covid. The symptoms of long Covid are varying, quite frequent, and are strikingly similar to ME/CFS. Between 10 – 30 % of patients who had Covid-19 will develop long covid.
Extensive research ongoing into all aspects of SARS-CoV—2 may prove valuable for understanding ME/CFS. Because of the high numbers of patients with viral disease and Covid-19, even a small percentage of patients exhibiting long disease becomes a big burden for society and, of course, the patients themselves. Effective prevention and treatment could reduce this burden.
The symptoms of long ovid vary and are complex, including cardiological problems such as myo- and pericarditis, neurological effects as cognitive impairment, brain fog, fatigue and dysautonomia. Gastrointestinal problems (including loss of smell and taste) may also occur as well as reproductive/genito-urinary/endocrinological, musculosceletal and immunological symptoms. These symptoms seem to reflect mainly an immunological response. Symptoms are less after vaccination, the use of antivirals or monoclonal antibodies, all resulting in a decreased viral load. Because of the varying and complex symptoms it is advised to work in a multidisciplinary team with different experts. The diagnosis of long covid is often made by exclusion.
A recent article in The Lancet described long-term symptom profiles after Covid-19 vs other acute respiratory infections (“long colds”). Data of 10,171 UK adults were analyzed: 1311 with SARS-CoV-2 infection (12,9 %), 472 with non-Covid-19 acute respiratory infection, average age 62,8 years, 68,8 % female and the vast majority were white.
Both types of infection were associated with increased prevalence/severity of most of the 16 potential Covid-19 symptoms and decreased health-related quality of life compared with no infection. In the Covid group more participants had problems with taste/smell, light-headedness or dizziness compared with those who had non-Covid-19 acute respiratory infections. They also suffered more heart palpitations, sweating and hair loss.
In the non-Covid group more people had a cough or a hoarse voice. Both groups suffered from breathlessness and fatigue. Memory problems and brain fog occurred more often in the Covid-19 group. Thus, recovery from acute respiratory infection may be slow regardless of cause. The severity of the original illness might be an important, but not the only key driver for long-tem symptoms. New research on long Covid might also help those people with “long colds”.
An important goal is the search for biomarkers of long Covid. In fact recent research (published in Nature 2023), making use of machine learning (AI), learned us that people with long covid have abnormal T cell activity and low levels of the hormone cortisol. Cortisol is a so-called stress hormone and helps people feel alert and awake, which would explain why they often report fatigue. The study also found that long covid appears to reactivate latent viruses including Epstein-Barr and mononucleosis. The illness long covid thus appears to interfere with complex systems such as immune and hormonal regulation.
References:
- Vivaldi G et al. Long-term symptom profiles after COVID-19 vs other acute respiratory infections: an analysis of data from the COVIDENCE UK study. Lancet 2023 https://doi.org/10.1016/j.eclinm.2023.102251
- Klein J et al. Distinguished features of Covid identified through immune profiling. Nature 2023 https://doi.org/10.1038/s41586-023-06651-y