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Human Metapneumovirus - Rise Of Underestimated Respiratory Threat

Human metapneumovirus, a relatively obscure virus causing symptoms similar to other respiratory infections, experienced a spike in cases during the spring.

Author:Karan Emery
Reviewer:James Pierce
Jun 02, 202315K Shares457.2K Views
The past winter witnessed a significant surge in respiratory viruses, with RSV, influenza, and Covid-19 dominating the headlines. However, amidst the decline of these well-known viruses, another stealthy pathogen quietly gained momentum.
Human metapneumovirus(hMPV), a relatively obscure virus causing symptoms similar to other respiratory infections, experienced a spike in cases during the spring.
It affected individuals of all age groups, particularly young children and seniors who are most vulnerable to respiratory illnesses.
With no vaccine or specific antiviral treatment available, hMPV became a concerning health issue. This article sheds light on the underestimated threat posed by hMPV, its impact on patients, and the challenges faced in combating this elusive virus.

Surge Of Respiratory Viruses During The Winter

During the winter months, respiratory viruses tend to thrive and spread rapidly, taking advantage of the cold weather and people spending more time indoors in close proximity.
Factors like low humidity, increased time spent in enclosed spaces, and decreased ventilation contribute to the heightened transmission of respiratory viruses.
This phenomenon leads to an upsurge in respiratory illnesses, particularly affecting the respiratory tract and causing symptoms such as cough, runny nose, sore throat, and fever.
The winter of the aforementioned period experienced a substantial surge in the prevalence of respiratory viruses. However, while the focus remained on well-known viruses like RSV, influenza, and COVID-19, a relatively unknown virus called Human Metapneumovirus (hMPV) was quietly gaining momentum.

What Is Human Metapneumovirus?

The human metapneumovirus (hMPV) is the most common cause of acute respiratory illness. Scientists in the Netherlands discovered it in 2001.
Children, those with low immune systems, and the elderly are the most vulnerable to hMPV infection consequences. hPMV is transmitted by close contact with an infected person or through contact with a contaminated location.
hMPV often produces symptoms comparable to a common cold that last 2-5 days and resolve on their own. The majority of hMPV infections occur in children aged 5 and less. A small percentage of affected youngsters (5-16%) may develop a lower respiratory tract infection such as pneumonia.
hMPV is most usually transmitted from person to person via intimate contact with someone who is sick by secretions from coughing and sneezing or by touching contaminated things such as toys or doorknobs.
hMPV is more likely to circulate in the United States during the winter and spring months, when other comparable illnesses, such as RSV and the flu, are prominent.
In patients of all ages, hMPV may induce upper and lower respiratory illness. It is, however, most frequent in young children and the elderly, where it is more prone to progress to bronchiolitis, bronchitis, or pneumonia.
Though a history of asthma, COPD, emphysema, or any other lung disease does not make someone more likely to get the condition, it might make symptoms worse if they have it.
This is especially true for persons with weaker immune systems, such as those receiving chemotherapy or recovering from an organ transplant.

Surge In Human Metapneumovirus Cases

Cases of human metapneumovirus, or hMPV, spiked this spring, according to the US Centers for Disease Control and Prevention's respiratory virus surveillance systems.
It filled hospital intensive care units with young children and seniors who are the most vulnerable to these infections.
At its peak in mid-March, nearly 11% of tested specimens were positive for hMPV, a number that's about 36% higher than the average, pre-pandemic seasonal peak of 7% test positivity.
Most people who caught it probably didn't even know they had it, however. Sick people aren't usually tested for it outside of a hospital or ER.
Unlike Covid-19 and the flu, there's no vaccine for hMPV or antiviral drugs to treat it. Instead, doctors care for seriously ill people by tending to their symptoms.
Studies show that hMPV causes as much misery in the US each year as the flu and a closely related virus, RSV. One study of patient samples collected over 25 years found that it was the second most common cause of respiratory infections in kids behind RSV.
A study in New York conducted over four winters found that it was as common in hospitalized seniors as RSV and the flu. Like those infections, hMPV can lead to intensive care and fatal cases of pneumonia in older adults.

Kids home with another virus? It might be human metapneumovirus

The Journey Of hMPV Discovery

Human metapneumovirus was discovered by Dutch virus hunters in 2001. They had 28 samples from children in the Netherlands with unexplained respiratory infections.
The researchers cultured the samples in various types of cells from monkeys, chickens, and dogs, and then they looked at the cultures under an electron microscope.
They saw something that seemed structurally related to the paramyxoviridae family, a group of viruses known to give people respiratory diseases like measles, mumps, and respiratory syncytial virus (RSV).
A closer look at the virus' genes showed a close relative: avian metapneumovirus, which infects birds. The new virus was dubbed human metapneumovirus. Scientists believe it probably jumped from birds to humans at some point and evolved from there.

Doctors And Patients In The Dark

Respiratory infections are the leading cause of death for children around the world and the No. 1 reason kids are hospitalized in the United States, but scientists don't know what causes a good chunk of them.
Human metapneumovirus doesn't account for all the unknown viruses, but it's a significant proportion – about as many cases as RSV or influenza. But no one knows about it.
Williams calls it "the most important virus you've never heard of." Because testing for hMPV is rarely done outside hospitals, it's hard to know the true burden of the disease.

Impact On Young Children And Seniors

hMPV, like many respiratory viruses, poses a significant threat to young children and seniors. Studies conducted over the years have demonstrated that hMPV causes a considerable burden of respiratory infections, rivaling the impact of other well-known viruses such as RSV and influenza.
Research indicates that hMPV is the second most common cause of respiratory infections in children, following closely behind RSV.
Moreover, studies conducted in hospitals have revealed that hMPV is as prevalent in hospitalized seniors as RSV and influenza.
In older adults, hMPV infections can lead to severe cases of pneumonia, requiring intensive care and, in some unfortunate instances, resulting in fatalities.
The vulnerability of these specific populations to hMPV highlights the need for increased awareness, surveillance, and preventive measures to mitigate the impact of this lesser-known respiratory virus.

Prevalence And Symptoms Of hMPV

While the spike in hMPV cases during the spring season was evident, it is important to note that most individuals who contract the virus may not even be aware of their infection.
Unlike COVID-19 and the flu, routine testing for hMPV is not common outside of hospitals or emergency rooms. Consequently, many cases of hMPV remain undiagnosed, and affected individuals often attribute their symptoms to other respiratory infections.
Common symptoms of hMPV infection include a lower lung infection, hacking cough, runny nose, sore throat, and fever. However, the clinical presentation may vary from person to person, with some experiencing mild symptoms or even being asymptomatic.

The Search For Solutions

Companies are working on vaccines against hMPV. Covid-19 vaccine maker Moderna just finished an early study of an mRNA vaccine against hMPV and parainfluenza.
The CDC recommends that doctors consider testing for hMPV in the winter and spring when it tends to peak.
Doctors don't test for it mostly because of a lack of awareness of the virus, Williams said, but also because a test probably wouldn't change the care they would give a patient. It would help them rule out other causes that do have dedicated treatments, like Covid or the flu.

How Is Human Metapneumovirus Diagnosed?

Your doctor will inquire about your symptoms and medical history to get a diagnosis of hMPV. Unless you or your kid has symptoms so severe that they need hospitalization, doctors will likely not order any testing.
Nose and throat swabs may be taken by your doctor. A fast antigen test or PCR (polymerase chain reaction) test is used to detect the virus in these samples.
A bronchoscopy may be recommended by your doctor if your case is very severe. The fluid sample is taken by inserting a thin tube with a tiny camera down the patient's windpipe (throat) and into the lung.

Personal Experience While Battling hMPV

Diane Davison caught human metapneumovirus during a family celebration in early April. Two weeks later, she was coughing so violently, she couldn't talk on the phone.
Her cough was so constant and deep, she was convinced she had finally caught the coronavirus after managing to avoid it throughout the pandemic. But she took six rapid tests for Covid-19, and all came back negative.
Davison is immunocompromised, so she has been cautious throughout the pandemic. Concerned about pneumonia, she got an X-ray from a radiology clinic near her home and was told it was clear. Her doctor wasn't satisfied, however, and sent her to an emergency room for more testing.
Blood tests determined that she had hMPV. Davison said hMPV gave her a serious bout of bronchitis. She was admitted to the hospital briefly for observation. She eventually got better, but she was sick for a month.
She's had respiratory infections before, of course, but she's particularly glad to be on the other side of human metapneumovirus, she said – "This was really kind of the worst I'd ever experienced."
As hMPV continues to pose a significant respiratory threat, raising awareness among healthcare professionals and the general public is crucial for early detection, appropriate care, and further research to develop effective preventive measures.

People Also Ask

How Is Human Metapneumovirus Transmitted?

Human metapneumovirus is primarily transmitted through respiratory droplets when an infected person coughs or sneezes. It can also spread by touching surfaces contaminated with the virus and then touching the mouth, nose, or eyes.

What Are The Symptoms Of Human Metapneumovirus Infection?

The symptoms of human metapneumovirus infection are similar to those of other respiratory illnesses. They include cough, runny nose, sore throat, fever, wheezing, and difficulty breathing. In severe cases, it can lead to pneumonia or bronchiolitis, especially in young children or individuals with weakened immune systems.

How Long Does It Take To Recover From Human Metapneumovirus?

The recovery time from human metapneumovirus infection can vary depending on the individual's age and overall health. In most cases, symptoms improve within 1 to 2 weeks. However, it may take longer for complete recovery, especially for individuals with weakened immune systems or underlying health conditions.

Is There A Vaccine Available For Human Metapneumovirus?

Currently, there is no specific vaccine available for human metapneumovirus. Prevention measures such as practicing good hand hygiene, avoiding close contact with sick individuals, and maintaining a healthy lifestyle can help reduce the risk of infection.

Who Is At Higher Risk Of Severe Complications From Human Metapneumovirus?

Young children, older adults, and individuals with weakened immune systems or underlying respiratory conditions are at higher risk of developing severe complications from human metapneumovirus infection. It is important for individuals in these high-risk groups to take extra precautions to prevent exposure to the virus.

Final Thoughts

Human metapneumovirus may be lesser-known than its viral counterparts, but its impact should not be underestimated. The recent surge in hMPV cases, surpassing pre-pandemic levels, has highlighted the need for increased awareness, research, and potential vaccine development.
As a significant cause of respiratory infections in children and older adults, hMPV demands attention from healthcare professionals and public health authorities.
By recognizing the importance of early detection, proper symptom management, and ongoing research efforts, we can hope to better protect vulnerable populations and mitigate the burden of this stealthy respiratory virus in the future.
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Karan Emery

Karan Emery

Author
James Pierce

James Pierce

Reviewer
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