Human metapneumovirus (HMPV) is closely related to the respiratory syncytial virus (RSV) in the Pneumoviridae family of respiratory viruses. Enveloped with a negative-sense single-stranded RNA genome, its clinical presentation includes causes of acute respiratory infections and is an important contributor to both upper and lower respiratory tract illnesses in different age categories, particularly in children, the elderly, and immunocompromised individuals. The first signs of this virus were recognized in the Netherlands after its discovery in 2001. The methodology used to characterize this virus, which had never been seen before, was RNA arbitrarily primed polymerase chain reaction (RAP-PCR), a technique designed to detect unknown viruses in cell cultures. Regarding HMPV, hospital admission is most common in infants between the ages of 6 and 12 months, which is a little later than the peak hospitalization age for RSV, which generally occurs in infants aged between 2 and 3 months. HMPV’s clinical manifestations and severity are notably similar to RSV infections.

Furthermore, HMPV is emerging as a significant cause of illness, especially among older adults and infants, marking its wide-reaching effects across age groups. Human Metapneumovirus (HMPV) is a pathogenic virus of the respiratory system that holds the potential to infect from infancy to old age. It is most commonly mild due to its healthiness. However, it is known to be lethal to infants, very young children, the elderly, and immunocompromised persons. This blog offers a discussion on certain signs and symptoms of HMPV in toddlers, children, and adults, the diagnosis scale, treatment options available to those affected, as well as how dangerous HMPV is, its recent spread across India, and outbreaks witnessed in China.  

How Much Dangerous is HMPV?

In general mild pretext infectious agents of respiratory diseases, HMPV have a serious impact on very young children, the elderly, and immunocompromised individuals. It starts with the cold, where most of them develop recurrent severe respiratory diseases like pneumonia that will subsequently have to be hospitalized. For most, it will not be labeled the most dangerous, but particularly for infants and people with pre-existing respiratory illnesses like asthma or COPD, this has an unfavorable prognosis. In the aforementioned case, the virus may “kick up” into bronchitis or pneumonia, which necessitates strenuous veterinary care. In high-risk groups, strict monitoring of HMPV symptoms is crucial. Severe infections, when left untreated, may then lead to respiratory failure, often with dire implications for the very young or the elderly.

Symptoms of HMPV in Infants, Children, and Adults

1. HMPV in Toddlers & Children

In toddlers and children, HMPV typically causes upper respiratory tract infections. Symptoms include:

• Coughing and sneezing
• Nasal congestion and runny nose
• Fever
• Difficulty breathing (in severe cases)
• Wheezing
• Fatigue

In some children, it can progress to more serious respiratory issues, such as bronchiolitis or pneumonia.

• HMPV Symptoms in Adults

In healthy adults, the symptoms of HMPV are usually mild and similar to those of a common cold, including:

• Runny nose
• Cough
• Mild fever
• Sore throat
• Shortness of breath (in rare cases)

In adults with compromised immune systems or pre-existing conditions like asthma or COPD, the symptoms might be more severe and could escalate into pneumonia or bronchiolitis.

How to Diagnose HMPV

The diagnosis of HMPV infection is based on clinical evaluative tests along with laboratory confirmation. Because of the respiratory viruses, mainly RSV or flu-like symptoms, this virus sometimes becomes difficult to identify based on symptoms alone. The diagnostic tests typically include:

• Polymerase Chain Reaction (PCR) Test: Detects the presence of HMPV in respiratory samples like nasal swabs.
• Blood Tests: Can show signs of infection.
• Chest X-ray: In severe cases, an X-ray can help identify pneumonia or other complications.

A confirmed diagnosis can help guide the treatment approach and rule out other similar respiratory viruses.

Chance of Hospitalization

Most patients with HMPV can bypass short hospitalization, although some cases do involve it. The factors responsible for hospitalizing a child include:

• Marked respiratory distress
• Age: infants or children under 2 years old
• Age: older adults
• Underlying disease-enhanced impairment of immunity

Hospital admission can involve supportive oxygen therapy, IV fluids, corticosteroids, nebulized treatment, and other forms of respiratory support.

Recovery

From the infection has occurred, recovery speed for the HMPV virus greatly depends on the severity of the infection coupled with the age and health condition of the individual.

• Mild cases: These cases could recover within a week or two, mainly with supportive care such as rest and hydration with over-the-counter medications to lessen symptoms of fever or congestion.
• Severe cases: Such infections usually require a considerably longer recovery time for the patient, specifically if they have been complicated by pneumonia or other respiratory conditions. Such cases could take weeks to recover, and some require hospital admission for full recovery.

Supportive care such as antivirals or oxygen therapy may help those who have severe symptoms to recover much faster.

Recent Outbreak in China – HMPV Virus

Towards late 2024 and early 2025, there seems to have been raised cases of infections of HMPV in China, observing a surge in hospitalizations, particularly among children and the elderly. The recent outbreak has triggered health authorities to heighten their efforts toward diagnosing and controlling this virus. HMPV has gained awareness not only from the current outbreak but also in consideration of possible transmissions going to warm and overcrowded countries all over the world.

Global Spread of HMPV

HMPV has circulated for years, and this outbreak in China acts as a reminder that respiratory viruses can hardly stay contained in one place. In general, health officials around the world keep track of HMPV cases because it is capable of wider infection, especially during colder months, when respiratory illnesses usually rise in frequency.

How Many HMPV Cases are there in India?

Cases of HMPV have been identified in India, with a steady rise in infections over the past few years. HMPV is getting recognition as an important respiratory disease in winter and early spring months, unlike COVID-19 and influenza, virus infections from which cases are being reported; however, they do not match the number of cases reported for HMPV, as its precise scope still awaits documentation. According to the Indian Council of Medical Research, the first confirmed cases of human metapneumovirus (HMPV) in India were reported by Indian officials, with seven confirmed by Tuesday.

These include two cases announced in Nagpur, two cases in Bengaluru, and one case each in Ahmedabad, Chennai, and Salem as of Monday. The two identified on Monday include a three-month-old girl, who tested positive, and an eight-month-old boy, also infected with HMPV and RSV. HMPV primarily affects the respiratory tract, causing infections in humans of all age groups. The main players at risk from HMPV are infants aged below 1 year, older adults, and those with compromised immune systems. Other signs could include cough, fever, nasal congestion, and difficulty breathing, according to CDC statements. The regional and small outbreaks have been noted since then. It is readily seen in about all of these other temperate countries where respiratory diseases gain momentum during cold periods. With rising awareness, doctors and health experts are urging for more testing and tracking for HMPV. The healthcare systems in India must ensure improved tracking of the virus, especially in areas wherein seasonal respiratory infections are prevalent.

HMPV Prevention

Prevention of HMPV primarily involves practicing good hygiene. No vaccines are in place since there is no vaccine available for HMPV. Therefore, the need for preventive measures takes priority:

• Wash hands often.
• Avoid close contact with sick individuals.
• Disinfect surfaces and objects that they touch every day.
• Keep indoor spaces well-ventilated.

Take care of people whose risk factors place them at a higher risk, such as babies and elderly adults, especially during the peak virus season.

HMPV is an important respiratory virus that can infect individuals of all ages, however, it poses a greater risk for infants, young children, the elderly, and immunocompromised persons. The majority of cases are mild; however, it is important to recognize the symptoms and seek medical attention when warranted. With the increase of cases across the globe, particularly in India and China, it is important to understand the proper ways to diagnose, treat, and prevent impacts due to the virus.