What is human metapneumovirus? Doctors explain HMPV symptoms

Human metapneumovirus, or HMPV, has spiked so far this year. 

As a respiratory virus, the symptoms sound familiar: hacking cough, fever, sore throat and lower lung infection. But young patients can be impacted in different ways.

"From mild illness, such as colds, children who were in the hospital for a couple of days needing extra oxygen and maybe extra fluids, to kids who are severely ill in the intensive care unit, sometimes needing mechanical ventilation, a breathing machine," said Dr. John Williams of UPMC Children’s Hospital of Pittsburgh.

HMPV was first isolated in blood samples in 1958. Scientists say it resembles an infection found in birds and that it likely jumped from birds to humans.

In the U.S., tests for HMPV are only done when a patient is hospitalized, so numbers have been low, but it is showing up in 11 percent of tests. 

While epidemiologists say 11 percent isn't alarming, they also say it's significant.

"If everybody can take really those common-sense steps when you're sick to try to just avoid spreading it – even if it's not serious for you, it may be for others. And so just do the sort of kind of thing and keep your germs to yourself," said Dr. Stephanie Silvera, a professor of epidemiology at Montclair University.

Respiratory illnesses are the number one cause of hospitalizations for children. A 2020 study in Lancet Global Health found most children under the age of 5 have been infected with HMPV by the time they reach that age. In the year that they sampled, 600,000 children had to be hospitalized and more than 16,000 died.

Here's what to be on the lookout for.

"If a child is having trouble breathing, like they're using their muscles to breathe a lot as if they're running a marathon, or if a baby cannot breastfeed or take a bottle because they're breathing so hard, those are signs that the parents should seek medical attention," Dr. Williams warned.