What is Human Metapneumovirus?
The Human Metapneumovirus (HMPV) is a common reason for infections in our respiratory system (the parts of the body involved in breathing), affecting children, adults, seniors, and those with weakened immune systems. This virus was relabeled in 2016 and is categorized into two main groups, A and B, which are each split further into four subclasses: A1, A2, B1, B2. These classes can change from year to year. Though HMPV was first spotted in the Netherlands in 2001, we now see it around the world. It’s mostly spread through tiny drops released by individuals infected with the virus when they cough, sneeze, or talk.
Generally, infection with HMPV occurs by the time a child turns five, but reinfection can happen at any point in life. The primary illness that results from HMPV is infection in the upper and/or lower regions of the respiratory system. Infections in the lower respiratory system are especially common, and these can lead to serious conditions such as pneumonia (lung inflammation), bronchiolitis (inflammation of the tiny air passages in the lungs), and severe asthma attacks. To treat HMPV, doctors usually provide supportive care, which may include extra oxygen, agents to reduce fever, and possibly intravenous fluids (fluids given through a needle into a vein) for hydration if necessary.
What Causes Human Metapneumovirus?
The Human Metapneumovirus (HMPV) is a type of virus that is surrounded by a fatty layer, and it carries its genes in a single strand of RNA. In 2016, scientists reclassified it to a different family and genus of viruses. It’s important to know that it is spread by droplets that come out when an infected person coughs or sneezes.
Severe infection with HMPV has been linked with situations like premature birth, a weakened immune system, and ongoing lung, nerve, or heart disorders.
Risk Factors and Frequency for Human Metapneumovirus
Human Metapneumovirus (HMPV) was first recognized in the Netherlands in 2001, but it’s believed to have been circulating since as early as 1958. While cases can occur at any time of the year, this virus is most commonly seen in late winter and early spring. HMPV infections can happen anywhere in the world. It comes in four subgroups: A1, A2, B1, and B2. All of these types cause similar levels of illness, and none of them dominates over the others.
- HMPV primarily affects children, especially those under 2 years of age. The average age of patients is 22 months.
- Almost all children have had an HMPV infection by the time they’re between 5 to 10 years old.
- HMPV is responsible for approximately 5 to 10% of hospitalizations due to severe lower respiratory tract infections in children.
- Children less than 6 months old with HMPV are three times more likely to be hospitalized than those aged 6 months to 5 years.
People can get infected with HMPV more than once. This is because there are different types of the virus, and the immunity that people get after the first infection may not be strong enough to fight off a second one. Adults usually have mild flu-like symptoms, but complications can arise in older people, those with a weaker immune system, or those with chronic lung diseases.
Signs and Symptoms of Human Metapneumovirus
Human metapneumovirus is a virus that can cause upper or lower respiratory tract infection. The symptoms can differ, based on whether the infection is in the upper or lower part of the respiratory system.
- Symptoms of upper respiratory tract infection may include coughing, runny nose, congestion, and a sore throat
- Lower respiratory tract infection symptoms might be wheezing, fever, cough, shortness of breath, and low oxygen levels. In kids, this type of infection can lead to bronchitis, sudden worsening of asthma, croup, and pneumonia, which can be serious enough to require a hospital stay.
- In adults, this virus can cause pneumonia, worsening of asthma symptoms, and a sudden increase in symptoms in those with chronic obstructive pulmonary disease
Gastrointestinal issues like diarrhea, nausea, and vomiting also have been noticed. Some people may also have an abnormal eardrum, which could be a sign of an acute ear infection. These symptoms can be quite severe in older adults (over 65), those with other health conditions, and those with a weakened immune system, including people with HIV, cancer, those undergoing immune therapies, and those who have had organ transplants.
Testing for Human Metapneumovirus
The identification of HMPV, a type of respiratory virus, usually doesn’t require additional tests. Instead, it’s mostly diagnosed based on the symptoms you’re experiencing. However, there are lab tests that can be used if needed.
The most common way to confirm an HMPV infection is through a lab test known as a reverse transcriptase-polymerase chain reaction (RT-PCR). This test takes a sample from the back of your nose and throat using a swab.
When it comes to X-ray pictures of the chest, the results are typically not specific unless HMPV has caused bronchiolitis (inflammation of the small airways in the lung) or pneumonia. The X-ray can show things like unusual densities or structures in some parts of a lung, thickening around the bronchi which are the airways in the lungs, overgrowth of the lung tissue, or unusual densities around the heart area.
It is very important to check vital signs like heart rate, respiration rate, temperature and perform a thorough physical examination to look for signs of difficulty breathing and to assess hydration status. This forms the basis to determine what kind of supportive care, like hydration or oxygen, might be needed.
Treatment Options for Human Metapneumovirus
The main treatments for HMPV include supportive care and symptom management. Over-the-counter medications such as acetaminophen and ibuprofen can be given to patients who have a fever. If patients are dehydrated and cannot drink enough fluids, they may need to be given fluids through an IV (a tube that goes into a vein).
In more serious cases, where HMPV leads to acute respiratory failure, some patients might need additional oxygen support. Options include a high-flow nasal cannula, which delivers oxygen through a tube in the nose, or mechanical ventilation, a machine that helps one breathe. This is especially likely if a patient has existing lung, heart problems, or a weakened immune system.
Patients with HMPV are usually able to recover fully. However, it’s important to isolate them from others, as the virus can be passed on through droplets when a person coughs or sneezes. This is known as droplet precautions and can help prevent the virus from spreading.
Currently, there is no vaccine available for HMPV. However, scientists are exploring different potential vaccines. Although these vaccines have only been tested in animals so far and have shown promise, they haven’t been trialed in humans yet.
What else can Human Metapneumovirus be?
If someone appears to have symptoms of HMPV infection, it’s necessary to rule out other similar health conditions or causes. These could be:
- Noninfectious causes like acute asthma and acute exacerbations of chronic obstructive pulmonary disease (flares of long-standing lung conditions).
- Bacterial infections that cause pneumonia.
- Other virus infections such as coronaviruses, rhinovirus, adenovirus, parainfluenza virus, respiratory syncytial virus, and influenza A and B.
Due to the similar symptoms, these possibilities need to be taken into account in order to properly diagnose and treat the patient’s condition.
What to expect with Human Metapneumovirus
In simpler terms, humans affected by the metapneumovirus generally have a good chance of recovery. However, the healthcare provider needs to be aware of any ongoing medical conditions a patient might have and check for signs of serious infection. These signs may include shortness of breath, hypoxia (when your body or a region of your body is deprived of adequate oxygen supply), and the use of additional muscles to breathe.
Typically, basic care and support are all that’s needed, leading to a full recovery for most patients. However, one can get this virus again. This suggests that our immune system’s defense against the metapneumovirus may be short-term and incomplete.
Possible Complications When Diagnosed with Human Metapneumovirus
Human Metapneumovirus (HMPV) can cause severe sickness that requires hospitalization in certain groups of people. These include individuals with weaker immune systems or existing heart or lung conditions. These patients are at higher risk for developing severe breathing problems needing high flow oxygen support, with some people’s conditions worsening to the point of needing machines to help them breathe. These severe cases often require close monitoring in the intensive care unit.
Vulnerable Populations:
- People with weakened immune systems
- Patients with pre-existing heart or lung conditions
Potential Complications:
- Acute respiratory failure needing high flow oxygen support
- Deterioration to the point of requiring mechanical ventilation
- Need for admission to the intensive care unit for close monitoring
Preventing Human Metapneumovirus
It’s very important to let patients and their families know how to properly clean surfaces at home. Hand washing is also super important. In addition to these, taking precautions against small droplets that could spread germs, like coughs or sneezes, is vital for keeping healthy.
