Everything we know about 'untreatable' mystery disease spreading all over world

While much of the world has officially checked out of work for Christmas, many families are working through the motions of all the various festive illnesses.

If it's not the super flu, it's Covid, and if it's not Covid... well, it might be a mysterious 'untreatable' disease, which is said to be spreading all over the globe.

Fear not: we're not talking about another pandemic situation, though a health expert has issued a warning over the virus, which happens to have similar symptoms to both coronavirus and the flu — and the chances are, you'll not even notice any difference.

According to Eric Sachinwalla, the medical director of infection prevention and control at Jefferson Health, based in Philadelphia and Pennsylvania in the US, an illness called adenovirus has recently spiked and is currently spreading like wildfire.

The common illness is 'untreatable' (Getty Stock Images)

What is adenovirus?

According to Public Health Scotland, adenovirus is a group of around 50 different viruses, causing a myriad of mild to moderate symptoms, though they can be severe when it comes to anyone with a weakened immune system.

The most common signs include cold or flu-like symptoms, such as a cough, runny nose, fever or chills.

Meanwhile, a sore throat, croup, swollen glands and acute bronchitis are also common.

Adenovirus can also cause pneumonia, conjunctivitis and acute gastroenteritis, which causes diarrhoea, vomiting, nausea and stomach pain.

Less common symptoms of the virus can include bladder inflammation or infection, or neurological disease.

How many people are affected by adenovirus worldwide

The majority of children have been infected by adenovirus by the time they reach 10 years of age and they won't even be aware of it.

There's currently no global count of how many people have experienced the virus, as the chances are most people in the world will have been infected at least once, but most likely several times, in their lives.

It's estimated that adenovirus accounts for between five and 10 percent of clinically significant respiratory infections in children and between one and seven percent of adults.

Meanwhile, around 75 million cases of diarrhea in children under the age of five are believed to have come from adenovirus in 2016 alone, according to the National Institutes of Health.

Adenovirus usually isn't serious unless a patient is high risk (Getty Stock Images)

What to do if you contract adenovirus

Unfortunately, there's no treatment for adenovirus, and it is unlikely to be killed by everyday disinfectant, meaning 'it tends to live in the environment longer', according to Dr Sachinwalla.

But if you do find yourself struck down by the illness, there is one thing you can do.

"The biggest thing is rest, which I know can be hard for some people," he told Philly Mag.

"You also want to stay hydrated. Not all fevers need to be treated with Tylenol or Motrin, either. A fever is actually a tool of your body’s immune system — it’s how we fight infection."

While there's no real way to tell if you have adenovirus over other common illnesses, like a cold, Dr Sachinwalla says the best thing to do is reach out to your GP if you're not feeling any better by day three of your symptoms.