For many of us, becoming ill with any virus might put us on the couch for a day or two. It can be draining, but after recovering we can generally get back to the things we’re used to. But for some people, contracting a viral infection can be life-altering. It can cause months, years or even a lifetime of debilitating symptoms that drastically reduce one’s quality of life.

These symptoms, sometimes called “post-viral fatigue syndrome”, have been reported by sufferers of many viral diseases including influenza, glandular fever, SARS, and now COVID-19.

What are the symptoms?

The World Health Organisation has classified post-viral fatigue syndrome under the section of “diseases of the nervous system”. It is defined as:

“A complex medical condition, characterised by long-term fatigue and other symptoms. These symptoms are to such a degree that they limit a person’s ability to carry out ordinary daily activities.”

Despite the word “fatigue”, the symptoms can be broader and more debilitating than simple tiredness. They can include a sore throat, aches and pains across the body, blood pressure changes, gastric upsets such as irritable bowel syndrome, headaches, sleep disturbance, depression, and dizziness. More severe neurological symptoms can also occur, including new sensitivities or allergic reactions, and burning or prickling sensations in the limbs. Many COVID-19 patients, for example, report a prolonged loss of smell and taste.

A key feature of the condition is that symptoms can suddenly worsen following only minimal physical or mental activity.

The symptoms are essentially the same as those of chronic fatigue syndrome, also called myalgic encephalomyelitis or ME, which is why the WHO places them under the same category of neurological disorders.

If you went to see a doctor, the clinical assessment for post viral fatigue syndrome would be the same as for chronic fatigue syndrome. However, not everybody who gets chronic fatigue syndrome has had a virus, which may explain why both terms persist. There are no current diagnostic tests for post-viral fatigue syndrome, and a diagnosis can only be made based on a series of symptoms.

It’s being reported in COVID-19 survivors

Post-viral symptoms have been reported following outbreaks of often unexplained viruses in many different countries. One of the earliest outbreaks recorded was in 1934 in California, where people infected with an unknown virus (thought to be polio) experienced ‘bursting headaches’, aching limbs and muscle weakness for a prolonged period.

For example, an Italian study from July 2020 found 55 percent of the hospitalised COVID-19 patients studied suffered at least three debilitating symptoms, two months after their apparent recovery from the initial infection. And a UK study in August 2020 estimated 10 percent of those with COVID-19 go on to develop post-viral symptoms.

This is not necessarily surprising, given research on other similar viruses. One Canadian study found 21 health-care workers from Toronto had post-viral symptoms for up to three years after catching SARS in 2003, and were unable to return to their usual work.

What causes it?

The condition, alongside chronic fatigue syndrome, is poorly understood. Researchers are still trying to understand how the body is affected, and for a way to objectively diagnose it.

Almost every part of the body is affected by a virus, and some lay dormant in our system and can be reactivated when our immune system is weakened. A good example of this is shingles, which is a reactivation of the chickenpox virus.

Autoimmune? Mitochondria?

While a virus might be the trigger, scientists do not yet know the actual cause. One theory is that post-viral fatigue syndrome may result from an overreaction of the body’s immune system, inducing widespread inflammation. This is highlighted by elevated levels of immune messengers called cytokines, which can cross the blood-brain barrier and potentially cause long-term toxic brain changes affecting the whole nervous system.

Researchers are also focusing on whether there’s an autoimmune component to the disease, where our immune system provides a rapid response which can inadvertently damage healthy tissue, affecting all of the body’s systems such as the heart, digestion, and may even cause diabetes.

Others are looking into why mitochondria, the structures that generate energy within cells, are affected and may result in fatigue. Researchers are also working toward finding “biomarkers” in the body, objective indicators that can help with diagnosing the condition, though no reliable ones have been located yet.

How is it treated?

Usually, treatment focuses on specific symptoms. If pain is the main feature, a rheumatologist might be used, who specialises in managing diseases of the joints, bones and muscles. Psychological treatments such as cognitive behavioural therapy or mindfulness might also help relieve some symptoms.

The most effective current treatment is total rest. This means focusing on rejuvenating activities as much as possible, with minimal mental stimulation such as television or screen time. If you are supporting someone with the condition, it is important to respect their need for rest and help them through the anxiety of endless tests in their search for answers. The experience of getting a virus during a pandemic is stressful, causing anxiety and even PTSD for some.

Unfortunately, there is no specific medication or speedy treatment for post-viral fatigue or chronic fatigue syndrome. Treatment options should always be recommended by a health professional and typically tailored to the individual, with a wellbeing approach.