Although long-lasting health issues following certain viral infections have been known for over a hundred years, the COVID-19 pandemic has shown that we need to learn more about the long-term effects of infectious diseases.
Almost any virus can trigger the so-called post-viral syndrome, including Epstein-Barr virus, cytomegalovirus, influenza virus, human herpesvirus, and enteroviruses. The post-viral syndrome affects millions globally and is similar to lingering symptoms seen in some Long COVID patients.
In a short blog series, we want to shine some light on the similarities and differences between Long COVID and other post-viral syndromes. The fist blog will focus on the most common symptoms associated with post-viral syndromes.
In two upcoming blogs the occurrence and some theories about the reasons why people develop post-viral syndromes as well as some insights on the diagnosis and management will be addressed.
Post-viral syndrome includes various symptoms
Post-viral syndrome, also known as post-viral fatigue, is a condition that includes a variety of symptoms like tiredness, headache, mood swings, depression, poor sleep, and difficulty in doing physical tasks. Other symptoms can include problems with memory and concentration, muscle pain and symptoms similar to having the flu.
The symptoms of post-viral syndrome may vary from person to person and can last for weeks or months, even after a person has recovered from the initial viral infection. The post-viral syndrome can develop even after a seemingly mild initial disease.
Chronic fatigue syndrome often appears after viral infections
The symptoms of post-viral syndrome are often similar, regardless of the type of infection, and they share features with a condition called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). ME/CFS is usually used as a measure for such ongoing problems, and it primarily involves extreme tiredness that does not get better with sleep or rest.
People with ME/CFS also experience worsening symptoms if they exert themselves physically, mentally, or emotionally more than they can tolerate (post-exertional malaise or crash). These flare-ups can last from days to months and may sometimes cause irreversible decline.
The exact cause of ME/CFS remains unknown and the physiological processes involved are currently being researched. For example, a recent study showed that the lack of energy and fatigue could be caused by a disruption of the cellular respiration in the mitochondria, the so-called “powerplant of out cells”.
ME/CFS often occurs following a viral infection
There is no specific test that can give a definitive diagnose of ME/CFS. Up to three-quarters of people with ME/CFS reported that their symptoms began after an event that seemed like an infection.
For example, a study in Norway found that the risk of being diagnosed with ME/CFS was doubled for people who got infected with the swine flu virus that was responsible for the 2009 swine flu pandemic. Another study reported that people with an infection caused by the varicella-zoster virus were also more likely to be diagnosed with ME/CFS.
Recent studies show that Long COVID and ME/CFS share about 20 symptoms and that both can affect multiple organs. While Long COVID specifically results from a SARS-CoV-2 infection, a variety of infections can cause ME/CFS. The syndrome is most likely a result to an inadequate response to those infections.
Rare diseases can follow viral infection
Certain rare diseases might also be connected to viral infections. One example is the Guillain-Barré syndrome, a rare, serious neurological disorder, which has been reported in association with various viral infections, including respiratory or gastrointestinal viral infections.
In patients with Guillain-Barré syndrome the body's immune system mistakenly attacks the nerves. The first symptoms usually include muscle weakness and tingling in the hands and feet.
The exact cause of Guillain-Barre syndrome is unknown, but two-thirds of patients report symptoms of infection six weeks before. These include coronavirus, cytomegalovirus, Epstein-Barr virus, varicella-zoster virus, influenza and Zika virus.