Human metapneumovirus, also called HMPV, is a virus that can infect the nose, throat and lungs, which are part of the respiratory system.

An HMPV infection can make you feel like you have a cold. It may cause illnesses such as croup or pneumonia. Most people get better quickly. But for some, HMPV can cause serious illness.

People who have a weakened immune system or other medical conditions, or who are very young or old, are more likely to get seriously sick from HMPV.

The first confirmed report of illness from human metapneumovirus in humans was in 2001. But looking at historical samples, researchers who study viruses find that HMPV has been spreading among humans for at least 50 years. HMPV is in the same family of viruses as respiratory syncytial virus, also called RSV.

Some people don't get any symptoms when they come in contact with HMPV. But if they do, symptoms most often appear about 3 to 6 days after exposure to the virus.

Common symptoms of HMPV infection in children and adults are:

• Fever.
• Cough.
• Wheezing or other lung sounds.
• Stuffy nose or runny nose.
• Shortness of breath.

Less often, people may have:

• Voice changes.
• Sore throat.
• Croup.
• Eye or ear infection.
• A rash that comes and goes.

Symptoms of HMPV infection may vary with a person's age. Symptoms also may vary for those who have other medical issues.

HMPV can have some similar symptoms to the common cold, coronavirus disease 2019 (COVID-19) or respiratory syncytial virus (RSV). If you have serious symptoms of any respiratory illness, your healthcare professional may suggest testing. Lab tests to tell which viruses are in your system can help the healthcare team know the best treatment options.

People with symptoms of HMPV infection likely can spread the illness for up to a week after symptoms start.

Human metapneumovirus spreads from person to person. When people with an infection cough or sneeze, shake hands, or touch another person, they can share the virus. HMPV can land directly on the face of a nearby person. Or you may touch a surface with the virus on it and then touch your eyes, nose or mouth.

You can get HMPV more than once.

Studies suggest that over time, almost everyone will catch at least one version, called a strain, of HMPV. The virus is found all over the world. It peaks in different places depending on seasonal patterns. Most people recover quickly, but for some, the HMPV virus can cause serious illness.

Most HMPV infections cause mild symptoms. But people who have a weakened immune system have a higher risk of serious illness with HMPV infection. That includes people who've had bone marrow or solid organ transplants and people with cancer. People being treated for HIV and people with a chronic heart or lung disease also are at higher risk.

Others who may be at high risk of serious illness include infants and young children, especially those 6 to 12 months old. HMPV infection also may cause serious illness in people age 50 and older.

HMPV infection can cause an ear infection or cause asthma to flare up. Getting an infection with the virus also may lead to a lung infection caused by bacteria.

For people who have had a lung transplant, HMPV can cause ongoing problems with how the lungs work.

You can lower the risk of an HMPV infection in a few ways:

• Wash your hands. Wash your hands well and often with soap and water for at least 20 seconds. If soap and water aren't available, use an alcohol-based hand sanitizer with at least 60% alcohol. Make sure friends and family who you're around regularly, especially kids, know the importance of hand-washing.
• Don't touch your face. Keeping your hands away from your eyes, nose and mouth helps keep germs away from those places.
• Clean surfaces. Regularly clean often-touched surfaces to prevent the spread of infection from touching a surface with the virus on it and then touching your face.
• Avoid people with symptoms. Try to avoid close contact with people who have symptoms of the illness.

If you have symptoms of HMPV infection, stay home until you feel better. Make sure you cough or sneeze into a tissue or your elbow. Then wash your hands. Avoid close contact with others, and don't share items such as glasses or eating utensils.

There's no vaccine for HMPV. But vaccines are available for viruses you can get at the same time as HMPV. Get all recommended vaccines, including vaccines against COVID-19, flu and RSV, to help avoid these illnesses.

HMPV infection causes the same symptoms as other common viruses, so it's most often diagnosed with a lab test. One test used to diagnose an HMPV infection looks for the virus' genetic material. It is called a polymerase chain reaction test, often shortened to PCR. You also may hear it called an NAAT test, which is short for nucleic acid amplification test.

Another test that may be used looks for viral proteins called antigens.

Treating an HMPV infection means taking care of your body as it clears out the virus.

If the infection is serious, you may need treatment in the hospital. To help your body clear out the virus, you may receive fluids through a vein in your arm. Oxygen may be given. Rarely, you may need a breathing machine to help you breathe.

For most people, an HMPV infection does not turn into a serious illness. But if you or someone in your care is at high risk for serious illness, follow up with your healthcare professional for specific ways to lower the risk.