HMPV not likely a concern for India but a 'winter challenge'

The Human Metapneumovirus (HMPV) is a known cause of respiratory infections, particularly affecting children and the elderly, causing global concern. However, it does not pose a significant public health risk in India.

Although the virus is capable of spreading disease, it has not presented an urgent or overwhelming challenge to the country’s healthcare system.

Overall, its impact has been milder compared to other respiratory pathogens, such as COVID-19 or influenza.

Seven infants have tested positive for HMPV in the Indian states of Karnataka, Maharashtra, Tamil Nadu, and Gujarat.

Tamil Nadu has reported two cases, one each in Chennai and Salem. Gujarat reported a case in a two-month-old infant who tested positive for the virus.

In Karnataka, two cases were confirmed through regular surveillance by the Indian Council of Medical Research (ICMR), involving a 3-month-old and a 4-month-old infant. Two additional cases have been reported in Nagpur, Maharashtra.

All the patients are said to be in stable condition following treatment in a hospital. There has also been an alarming rise in HMPV cases in Malaysia.

The virus was officially discovered in the Netherlands in 2001 and belongs to the Paramyxoviridae family, which also includes Respiratory Syncytial Virus (RSV).

It can cause a range of respiratory illnesses, from mild conditions like the common cold to more severe disorders such as pneumonia and bronchiolitis.

In 2001, researchers sequenced the virus, and subsequent serological investigations revealed that HMPV had been circulating since 1958.

There have been occasional increases in cases, with a particularly high rise reported in the United States in early 2023.

Respiratory illnesses are common, especially during the monsoon and winter seasons, but HMPV has not emerged as a major cause for concern in India.

There are several reasons for this, including the country’s demographic profile, environmental factors, existing healthcare infrastructure, and the ongoing management of respiratory diseases.

India is less likely to experience large-scale HMPV outbreaks due to its tropical climate. Unlike temperate regions where cooler, dry weather promotes the spread of respiratory viruses, India's warm and humid conditions can help limit virus transmission.

HMPV typically thrives in cold, dry climates, with outbreaks most common in winter and spring. However, India lacks a distinct winter season in many areas, preventing the virus from reaching epidemic levels.

Overall, the tropical climate leads to lower HMPV prevalence, reducing the chances of widespread outbreaks.

Dr. Rajesh Karyakarte, a professor of microbiology at BJ Medical College in Pune, explained, “Our bodies have adapted to the virus over time. In most cases, infections with all viruses remain asymptomatic or mild, but for some individuals—especially those with underlying medical conditions—these infections can lead to severe illness and hospitalization.”

“This was true for COVID-19, and it’s also true for HMPV. However, unlike COVID-19, HMPV has been around for a long time, and there is no evidence suggesting that it is spreading in India any faster than before,” he added.

Some individuals who contract the virus may experience mild symptoms similar to a cold, while others may develop severe pneumonia or bronchopneumonia.

Children, particularly those under the age of two, are most susceptible to HMPV, with 5–10% of pediatric cases resulting in hospitalization for acute lower respiratory infections.

Hospitalization rates are three times higher for infants under six months.

Fever, coughing, shortness of breath, and wheezing are common signs of HMPV infection. The virus has an incubation period of three to five days and spreads through respiratory droplets.

According to the US Centers for Disease Control and Prevention (CDC), the primary treatment for HMPV is supportive care, as no specific antiviral medication or vaccine is currently available.

While HMPV often causes moderate, self-limiting symptoms in healthy adults, it can be more severe in newborns, the elderly, and individuals with weakened immune systems.

It is widely accepted that HMPV causes seasonal respiratory infections, with the majority of outbreaks occurring in the winter months. There is currently no specific antiviral treatment or vaccine for HMPV.

Prevention measures include washing hands for at least 20 seconds, avoiding close contact with sick individuals, refraining from touching the eyes, mouth, or nose with unwashed hands, covering the mouth when coughing, staying home when sick, and regularly cleaning frequently touched surfaces.

Dr Amitav Banerjee, former field epidemiologist in the Indian Armed Forces, noted, “The recent surge in cases in China is attributed to 'immunity debt.' Children born during the pandemic did not get exposed to the virus during the early months of life due to restrictive non-pharmacological interventions. As a result, they are immune-naive and vulnerable, leading to a large number of cases.”

Dr Karyakarte also explained, “The mucus in our nasal passages, which serves as a protective barrier against pathogens, becomes less effective in cold, dry air. Reduced moisture in the mucus compromises this natural defense, making it easier for viruses to directly infect nasal cells.”

A pioneering study by BJ Medical College and NIV-Pune in 2003 confirmed HMPV in children in Pune.

The 26 pediatric cases revealed a positivity rate of 19.2%, with four of the positive cases being infants under the age of one. The infections ranged from mild to severe.

A 2006 study at AIIMS found that 12% of children under five years old, who had acute respiratory illness (ARI), were HMPV-positive. Most cases occurred during the winter months.

In 2013, a study by NIV-Pune analyzed 224 clinical samples and identified multiple strains of HMPV (A2, B1, and B2 lineages), with A2 and B2 being the predominant subtypes.

A 2014 study in Assam found HMPV in 20 out of 276 children (7.2%) under the age of five who showed symptoms of ARI.

The study also reported the highest prevalence of HMPV in January (46.7%) and December (16.7%).

A 2024 ICMR study in Gorakhpur, which examined 100 pediatric patients suffering from acute respiratory illness, found that 4% were positive for HMPV, with one reported death among the positive cases.

Dr Soumya Swaminathan, former chief scientist of the World Health Organization, stated, "It's a known virus that causes respiratory infections, mostly mild." She advised taking "normal precautions" as one would during a cold: wearing a mask, washing hands, avoiding crowds, and consulting a doctor if severe symptoms arise.

Union Health Minister JP Nadda said, “Health experts have clarified that HMPV is not a new virus. It was first identified in 2001 and has been circulating worldwide for many years. HMPV spreads through the air via respiration and can affect individuals of all age groups. The virus is more prevalent during the winter and early spring months.”

“Regarding recent reports of HMPV cases in China, the Health Ministry, ICMR, and the National Centre for Disease Control are closely monitoring the situation in China as well as in neighboring countries,” he added.