Human Metapneumovirus (HMPV): What You Need To Know

Human Metapneumovirus (HMPV) is one of the causes of respiratory illness in humans. Discovered in 2001, HMPV belongs to the Paramyxoviridae family and is closely related to Respiratory Syncytial Virus (RSV). HMPV is a widespread and impactful respiratory pathogen that often goes unnoticed. This is mostly due to the similarities it shares with other respiratory viruses.

What is Human Metapneumovirus (HMPV)?

Human Metapneumovirus is an RNA virus first isolated in the Netherlands from young children with respiratory infections. It is thought to have originated from birds, as it shares genetic similarities with Avian Metapneumovirus (AMPV), a virus that affects birds. Over time, it adapted to infect humans and is now a globally recognised pathogen affecting people of all ages.

How is Human Metapneumovirus Transmitted?

Human Metapneumovirus spreads primarily through respiratory droplets when an infected person coughs, sneezes, or talks. It can also spread through direct contact with contaminated surfaces or objects. The virus is highly contagious, particularly in crowded settings such as schools, daycare centres, and nursing homes. People are most contagious during the early stages of illness, even before symptoms become severe.

According to studies, in temperate regions, HMPV mainly spreads in late winter and spring, alongside respiratory viruses like RSV and seasonal flu. However, it remains active at lower levels year-round, continuing to cause illness in some people.

Who is at Risk?

1. HMPV affects individuals across all age groups but poses a higher risk to:
2. Young children, especially those under 5 years old
3. Elderly individuals, particularly those over 65 years old
4. Immunocompromised individuals, such as cancer patients or transplant recipients
5. People with chronic respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD).

What Are the Symptoms of Human Metapneumovirus (HMPV)?

HMPV infections range from mild to severe and may mimic other respiratory illnesses. Common symptoms include:

1. Mild cases: Runny nose, cough, sore throat, fever, and fatigue
2. Severe cases: Wheezing, shortness of breath, chest tightness, and hypoxia
3. Complications: Pneumonia, bronchitis, and exacerbation of underlying conditions, particularly in vulnerable populations

Symptoms typically appear 3 to 6 days after exposure and can last up to 10 days. Severe cases may require hospitalisation.

How is Human Metapneumovirus Diagnosed?

Diagnosing Human metapneumovirus can be challenging due to its similarity to other respiratory viruses. Laboratory testing is essential for confirmation and may include:

1. RT-PCR (Reverse Transcription Polymerase Chain Reaction): The gold standard for detecting HMPV RNA in respiratory samples
2. Antigen Detection Tests: Useful for rapid diagnosis in clinical settings
3. Serology: Detects antibodies to HMPV but is less commonly used due to delayed antibody response

Treatment of Human Metapneumovirus (HMPV)

There is currently no specific antiviral treatment for human metapneumovirus. Management focuses on supportive care to relieve symptoms and prevent complications. This includes:

1. Hydration: To prevent dehydration from fever or respiratory distress
2. Oxygen Therapy: For patients with severe respiratory symptoms
3. Bronchodilators: To alleviate wheezing and airway obstruction
4. Mechanical Ventilation: In extreme cases where respiratory failure occurs

Antibiotics are not effective against HMPV since it is a viral infection. However, they may be prescribed if secondary bacterial infections develop.

How to Prevent Human Metapneumovirus (HMPV)

Preventing human metapneumovirus transmission involves basic respiratory hygiene and infection control measures.

1. Hand Hygiene: Frequent handwashing with soap and water or using alcohol-based hand sanitizers
2. Respiratory Etiquette: Covering the mouth and nose with a tissue or elbow when coughing or sneezing
3. Disinfection: Cleaning frequently-touched surfaces like doorknobs and countertops
4. Avoiding Close Contact: Staying away from infected individuals and crowded spaces during outbreaks

Public Health Impact of Human Metapneumovirus (HMPV)

Human metapneumovirus is a significant contributor to respiratory illness worldwide, accounting for a considerable proportion of hospitalisations and outpatient visits, particularly among children and the elderly. Studies estimate that HMPV is responsible for up to 10% of respiratory infections in children under 5 years of age. Its burden is comparable to that of RSV and influenza, yet public awareness remains low. While most infections are mild, the virus can cause severe illness in vulnerable populations. This highlights the need for increased awareness and preventive measures.

Ongoing research and advancements in diagnostic tools, vaccines, and treatments hold promise for reducing HMPV’s global burden. Until then, adhering to simple hygiene practices remains the most effective way to protect yourself and others from this pervasive virus.