Bhubaneswar: The birth place of hMPV is not China. This respiratory virus was first identified in the Netherlands 24 years back – in year 2001.

However, serologic (blood serum) studies of antibodies against HMPV indicate that the virus is not new and circulated in humans for at least 50 years, suggest US CDC data.

hMPV GLOBAL BURDEN

In 2018, it was estimated that around 11.1 million cases of acute lower respiratory infections globally were attributable to HMPV, leading to approximately 502,000 hospitalizations and 113,000 fatalities, shows the US, CDC data.

CHINA’S TRYST WITH hMPV

The virus was in circulation in China since 2005.  

It was place: Changsha. And year was 2007-2008. 

The prevalence and clinical characteristics of hMPV were determined in nasopharyngeal swabs of children. 

A RT-PCR employed to screen for both hMPV and other common respiratory viruses in 1,165 nasopharyngeal swabs taken from children with lower respiratory tract infections. 

Seventy-six of 1,165 (6.5%) specimens were positive for hMPV, of which 85.5% occurred in the winter and spring seasons.

CHINA CDC 2024 STUDY ON hMPV

hMPV outbreak in China in 2024-25 is not a new outbreak. Records with China Centre for Disease Control and Prevention (CDC) shows controlled outbreaks in one or two provinces since 2007.

In the United States, the early 2023 detection rates for HMPV rose from 7% to between 10% and 19%

China has recorded two big outbreaks in 2018 and 2019, suggest the CDC data.

Henan, a populous province in China, has maintained ongoing surveillance for influenza-like illness (ILI) since 2010 and severe acute respiratory infection (SARI) since 2015.

Following consistent outbreaks leading to mortalities, the CDC has conducted an exhaustive study on hMPV taking the specimens collected from 2,707 ARI patients from a longer period from October 2017 to March 2023. The age of participants ranged from 5 months to 17 years.

The study has the following details.

• Children under five exhibited the highest infection rate.
• 1 in 3 hMPV patients have co-infections like Influenza, Respiratory syncytial virus and rhinovirus (that cause common cold)
• 1 in every 2 has developed Pnuemonia
• The 2018 and 2019 HMPV outbreaks predominantly occurred in spring
• The peak positivity rates touched with 31.11% in 2018 and 19.57% in 2019.
• Change witnessed in year 2020.
• Peak infectivity touched historic high of 42.11% from November 2020, and continued till January 2021 – the timeline when COVID-19 was at its peak across the world and China
• From February 2021 through March 2023, no significant seasonal peaks were observed.
• The infection rate was also greater in females than in males  
• There are two types of hMPV virus –  subtype A , B
• Subtype B was more dominant in China in year 2023-24.
• HMPV subtypes A and B, further divided into six genotypes: A1, A2a, A2b, A2c, B1, and B2
• The study shows the dominant strains were A2c111nt-dup in subtype A and B2 in subtype B.
• In China, A2c111nt-dup (nt-dup means nucleotide duplication) strains have been detected in Guangdong, Beijing, and Shandong provinces, suggesting their potential emergence as dominant strains.
• Genetic analysis from this study suggests that HMPV-A and HMPV-B either prevailed independently or concurrently over different years, 
• Displaying a potential subtype switch pattern described as “AAABBA” from 2017 to 2022 in Henan Province. 
• China is using the genotypes sequenced for developing of relevant vaccines and immunization policies.

HOW TO KNOW hMPV?

As per the CDC, China study, the prevalence of HMPV was higher in patients with ILIs compared to those with SARIs.

WHAT IS INFLUENZA LIKE ILLNESS?

As per medical classification, ILI cases were defined as – 

• An acute respiratory illness with a measured temperature of ≥100 deg F
• Plus cough, with onset within the last 10 days

WHAT IS SEVERE ACUTE RESPIRATORY INFECTION?

A case is described as Severe Acute Respiratory Infection (SARI) with ---

• An acute respiratory illness with a history of fever or measured fever of ≥100 deg F and
• cough, with onset within the last 10 days that necessitates hospitalization

PREDOMINANT SYMPTOMS

• Fever 
• Sore throat
• Purulent Cough (means changing of colour of sputum from white to deep brown or yellow in a short time span) 
• Expectoration (running nose and wet cough). 
• Bronchitis 
• Wheezing (sound while breathing like asthama patients)
• ALSO the following symptoms observed
• 1) Conjuctivitis (eye infection)
• 2)Ear infection

IN HOW MANY DAYS hMPV GETS SEVERE?

As per studies in Journal of Medical Biology, study on mice shows, initially HMPV infection in the lung is characterized by inflammation with alveola lining cells from day 3 with a peak on day 5.

The inflammation of inner lining of lungs alvela (air sacc) will make the patient harder to breathe.

The study shows the inflammation subsides after five days, only to return with bang after 2-3 weeks, to develop in a more prominent peribronchiolar and perivascular infiltrate – leading to airway obstruction in mice.

The mice hMPV study shows such conditions in lungs continuing for 70 long days, indicating long-term pulmonary inflammation after HMPV infection.

WHO ARE CARRIERS OR SPREADERS?

Though in young children, HMPV is the second most common cause of lower Respiratory tract infection after RSV, with children less than one year of age showing the highest rates of infection]. Seroprevalence (means antibody generated) at the age of 5 is almost 100%

• Adults may turn spreaders
• Because HMPV infection might be asymptomatic or 
• might have symptoms ranging from mild upper RTI symptoms
• Though at times depending on their immunity status, they may have episodes of severe pneumonia and dyspnoea (painful breathing). 
• However, as most adult patients (less than 35 yrs age) show only symptoms of
•  cough, 
• nasal congestion, they remain undetected but remains a potential spreader to child or elderly. 

WHEN TO SEE DOCTOR?

Immediately, report to a good doctor, if you have the following conditions.

• Difficulty in Breathing.
• Chest Pain
• Horribly running nose
• Such symptoms continuing for 10 days, despite normal intake of paracetomol.
• If a kid of over 3 month having fever and showing signs of lethargy.

TREATMENT FOR MILD CASES

Though no treatment or vaccine is specified for hMPV, the treatment in mild cases is akin to treatment for cold and cough.

• Need to take lots of fluids to prevent dehydration,
• Use decongestants to reduce congestion,
• For mild body aches, non-steroidal anti inflammatory drugs like ibuprofen, diclonofec etc.
• No need to take antibiotics, it will not act against virus.

Tags: prameyanews