Old ailment, known pathogen: A warning against HMPV panic
HMPV is a common respiratory virus with low alarm; many are exposed by age 5. Current Indian cases are mild, with no unusual surge reported.
For everyone holding their breath over fears of HMPV, here’s a quick summary: it’s an old ailment, caused by a known pathogen, and many people are likely to have been exposed to the virus by the time they are five years old. Now, read on, and as the good book says: Don’t Panic!
Several states on Monday announced they had detected infections of the human metapneumovirus (HMPV), days after reports of an outbreak in China caused concern in India, especially as it came on the fifth anniversary of the Sars-CoV-2 outbreak in the Asian nation where news of its early spread was regarded to have been suppressed.
But the current outbreak – there is no reliable confirmation whether there even is a concerning outbreak of HMPV in China – poses no reasons for alarm, experts and officials reiterated on Monday, amid growing panic in India.
“It is emphasised that HMPV is already in circulation globally, including in India, and cases of respiratory illnesses associated with HMPV have been reported in various countries,” stated India’s health ministry, noting that current data from both the Indian Council of Medical Research (ICMR) and the Integrated Disease Surveillance Programme (IDSP) show no unusual surge in Influenza-Like Illness (ILI) or Severe Acute Respiratory Illness (SARI) cases in the country.
Additional professor for internal medicine at AIIMS Delhi, Dr Neeraj Nischal, added: “Let’s not compare this (HMPV) with Covid-19 because that was a completely new virus and none of us had immunity against it. HMPV has been described since 2001, and even based on evidence, it dates back to late 1950s. By the age of 10, a majority of children develop immunity against this virus.”
The alarm surrounding HMPV stems from a lack of awareness. The virus has been silently circulating in human populations for over five decades, and is estimated to have jumped from birds to other species some 200 years ago.
The virus’s widespread presence and typically mild manifestation place it among the common respiratory pathogens that affect populations worldwide. Most cases present with cold-like symptoms, with adults generally protected by immunity developed through previous exposures. However, infants encountering the virus for the first time and individuals with compromised immune systems may experience more severe symptoms.
That the pathogen is endemic is well-documented. A 10-year German surveillance study published in PLOS ONE in 2014 identified it as one of the most common respiratory pathogens worldwide, with nearly everyone exposed by the age of 5. The German data revealed that HMPV typically manifests with cough in 94% of cases and fever or shivers in 88%, occasionally progressing to bronchitis or pneumonia.
This understanding is reinforced by recent Indian research. A December 2023 paper analysing data from Delhi hospitals identified HMPV as one of several common respiratory viruses contributing to acute respiratory tract infections (ARTI).
“Acute respiratory tract infection is a proven infectious cause of mortality among children under five years and varies geographically and seasonally significantly across the globe,” researchers from ILBS and Max Healthcare noted.
While influenza virus infections predominate among respiratory viral infections, other non-influenza viruses, including HMPV, were increasingly recognised as primary agents for respiratory diseases, alongside respiratory syncytial virus (RSV), parainfluenza virus, human coronaviruses, and adenovirus, the research found.
Dr Ekta Gupta, lead virologist at the Institute of Liver and Biliary Sciences and one of the paper’s authors, provided historical context: “HMPV is a part of the flu panel that have been tracking as part of government’s influenza like illnesses (ILI) surveillance initiative since 2016. The detection rate of hMPV is about 10% among all ILI samples and it has not changed. There’s no unusual rise.”
Recent surveillance has identified two specific cases in Karnataka, both signalling that the virus is mostly detectable in very young children, for whom it is usually the first exposure.
The first case involved a three-month-old female infant admitted to Baptist Hospital, Bengaluru, with bronchopneumonia. She has since been discharged. The second case, an eight-month-old male infant, tested positive on January 3 after being admitted to the same hospital with similar symptoms. The infant is currently recovering. Notably, neither patient had any history of international travel, reinforcing the endemic nature of the virus in the region.
Dr Ankita Baidya, consultant in infectious diseases at Manipal Hospital, suggests the apparent increase in cases might be attributed to enhanced testing. “As such, there is no need to panic. The numbers that we are seeing is because of the alert that has resulted in increased testing. If we test more for HMPV, we will find more cases as the virus is in circulation India since long. What should be worrisome is if there is an increase in the number of hospitalisations, which is not the case yet.”
The health ministry maintains active monitoring through available surveillance channels, with ICMR continuing to track HMPV circulation patterns throughout the year.
The recent preparedness drill conducted across the country has demonstrated India’s robust capability to handle potential increases in respiratory illnesses, with public health interventions ready for deployment if needed.
