What is HMPV? The infectious respiratory disease spiking this year in US

Although Covid-19 and Respiratory Syncytial Virus (RSV) cases are decreasing, another respiratory virus known as human metapneumovirus, or HMPV, is spreading across the United States.

Last week, the Centers for Disease Control and Prevention (CDC) reported an increase in HMPV cases nationwide.

The organisation said that at its peak in mid-March, nearly 11 per cent of tested specimens were positive for HMPV, a number that's about 36 per cent higher than the average pre-pandemic levels.

What is HMPV?

The HMPV, discovered in 2001, is a paramyxovirus, a type of virus that causes various common infections. Other paramyxoviruses include parainfluenza, respiratory syncytial virus (RSV), measles, and mumps.

Why are people talking about HMPV?

Cases of HMPV, like other respiratory illnesses, have been on the rise. The Centres for Disease Control and Prevention (CDC) reported unusual spikes in cases across the United States last month.

Virus experts believe the increase in various viruses, including RSV, is the result of Covid-19 lockdowns and masking.

Small interactions with viruses prime our system to handle future virus exposures better. However, after years of masking and social distancing in school, children have fewer biological defences to combat multiple viruses simultaneously.

What are the symptoms of HPMV?

The virus, which is most common in the winter and spring, primarily affects the upper respiratory tract, causing nasal congestion, coughing, shortness of breath, and fever. It lasts three to seven days on average, depending on severity.

Is HPMV ever serious?

Human metapneumovirus is typically mild but can have serious consequences in young children, the elderly, and those with weakened immune systems.

In some cases, it can spread to the lower respiratory tract, resulting in a more serious illness such as bronchiolitis, which causes swelling, irritation, mucus buildup in the lungs, or pneumonia, Monica Gandhi, an infectious-disease expert at the University of California, San Francisco told the Washington Post.

How is HPMV transmitted?

According to the CDC, HPMV is spread through airborne particles produced by coughing or sneezing, physical contact with a person who has the virus, or handling contaminated objects and then touching the eyes, mouth, or nose.

The virus can spread even when people are asymptomatic.

In one study, asymptomatic human metapneumovirus infections accounted for at least 38 per cent of infections.

Is a vaccine available? What is the treatment for HMPV?

Human metapneumovirus has no vaccine, and treatment is limited to supportive care.

"We try to make you feel better and ensure that your breathing is okay while your body fights off the virus," said William Schaffner, a professor of infectious diseases and preventive medicine at Vanderbilt University.

Although it is uncommon, Schaffner stated that in severe cases of people having difficulty breathing, "we can put them in an intensive care unit and treat them there," but most people recover independently.

Human metapneumovirus is a respiratory virus that has been around for decades, unlike the novel coronavirus and its variants that cause Covid-19, said Gandhi.

"Hopefully, in the future, we will see progress against human metapneumovirus. But we've been dealing with it for a long time," she said, adding, "This isn't going to start a pandemic."