‘Killer’ virus you’ve never heard of that triggers ‘pyramid of disease is hiding in plain sight’

A VIRUS that is “hiding in plain sight” could be set to return this spring, experts warn.

Human metapneumovirus (hMPV) can cause hospitalisation and death in the clinically vulnerable, and cases are already beginning to increase.

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Nearly 7.5 per cent of people in the US tested positive for the virus in mid-March, according to the Centers for Disease Control and Prevention — the highest level since April last year.

And the latest data show cases are also starting to rise in Britain, with 4.1 per cent testing positive in the week up to March 17, according to the UK Health Security Agency.

Dr Ed Hutchinson, of the University of Glasgow, told The Sun: “hMPV is a classic example of a virus ‘hiding in plain sight’.

“It was only identified by genetic sequencing in 2001, at which point it was realised that it is a very common respiratory illness, is found all around the world, and causes some quite serious disease. 

“Like a lot of viruses, hMPV will cause a ‘pyramid of disease’. 

“Most cases are really mild or light colds, there’s a small proportion of more serious cases and then a tiny proportion of deaths. 

“Because these viruses are really common, that creates something that looks like a paradox. 

“The rare cases do add up and make a lot of people very unwell, creating real misery and putting pressure on the health service.”

Human metapneumovirus has many of the same symptoms as Covid and flu, and can lead to killer pneumonia in a small number of patients.

Symptoms include a runny nose, sore throat, cough and wheezing.

Studies show that over the last four years, it was just as common as respiratory syncytial virus (RSV) and flu in pensioners in hospital.

It was also the second most common cause of respiratory infections in kids behind RSV in the last 25 years.

A study in the Lancet Global Health estimated that there were 14.2million hMPV infections in children under the age of five in 2018.

There were likely also more than 16,100 deaths and 643,000 hospitalisations, researchers said.

Most people who catch hMPV have no idea as testing outside of hospitals is rare.

UK cases so far this season are low but they are rising slightly in the latest data

Dr Ian JonesUniversity of Reading

UKHSA figures show current test positivity for hMPV is higher than at any point over the last 12 months.

Dr Ian Jones, of the University of Reading, told The Sun: “Cases normally peak early in the year and then tail off although there is always a certain amount around.  

“UK cases so far this season are low but they are rising slightly in the latest data. Like flu, we might end up having a good year or a poor year but it’s very hard to predict.

“For most people it will be no more than a common cold.

“But, along with RSV, it can cause lower respiratory tract infections which are more serious and may require hospitalisation. 

“As ever it is the old and very young that are most at risk. “

Dr Simon Clarke, of the University of Reading, added: “hMPV is another one of those viruses that do the rounds every year, peaking in late winter or early spring.

“It causes cold-like symptoms and in most people the illness is pretty mild, but in the very old, young children and people with weaker immune systems, it can cause a more severe respiratory illness.  

“It’s just one in a long list of viral infections that peak around this time of year, many of them causing very similar symptoms.  

“There isn’t much point worrying which type of virus is causing you to feel under the weather, the right thing to do is to maintain good hygiene and reduce the chance of spreading it to family and friends.”

Professor Jonathan Ball, of the University of Nottingham, said: “UK Respiratory DataMart laboratory surveillance has indicated a slight uptick in cases, especially in children under five years of age.

“For most people, the virus is nothing more than an annoying respiratory infection, but it some, especially young children infected for the first time, people who have weakened immune systems and some elderly people, the infection can cause more serious disease.”