Human Metapneumovirus (HMPV) is a human respiratory virus that has recently received much attention after a number of cases of this virus emerged in an outbreak primarily in East Asia. HMPV was first seen in 2001 and was causing several respiratory infections that manifested very mildly as mere cold-like symptoms but highly severe in conditions that affect the lower respiratory tract, mainly in children under three years of age, elderly people, and immunocompetent individuals.
Symptoms
HMPV infections can appear as a standard cold or flu. The most common symptoms are:
- Cough
- Fever
- Stuffy nose or nasal congestion
- Sore throat
- Wheezing
- Difficulty breathing
- Rash
Most patients develop mild illness and are cured without serious consequences after 7 – 10 days. The risk of more serious complications, for others, escalates to considerable levels and even leads to pneumonia and bronchiolitis diseases.
HMPV is seasonal. It peaks in all parts of the globe during spring and winter periods that do not make exemptions to Hong Kong. The time frames coincide with other respiratory viruses. The seasonality increases morbidity for the respiratory disease.
Management/Diagnosis
In a confirmed case of HMPV, there is care offered to the patient, as well as infection control. Some of these diagnostic techniques are as follows :
RT-qPCR, or Real-time Polymerase Chain Reaction
This is the gold standard in the detection of HMPV. It may be very sensitive and can give a readout as early as within 1-3 hours from the sampling procedure. It also gives a quantification of the viral load. This technique has been applied highly in the detection of particular genetic material for HMPV, though RT-PCR is relatively less sensitive, and its popularity in clinical diagnosis hasn’t gathered much momentum recently.
LAMP
LAMP is the abbreviation for Loop-Mediated Isothermal Amplification. The benefits of the LAMP techniques are that they provide more advantages in detecting the pathogens without involving in the thermal cycle and with an effective visual appearance. However, the LAMP technique is a little more expensive compared to the one done with the help of the PCR-based test.
Virus isolation
Although it is one of the gold standards in isolating viruses from patients’ specimens, it is observed to be time-consuming. Moreover, it is cost-intensive in the laboratory and requires labour.
Imaging Studies
In the case of lower respiratory tract infections, imaging studies like chest X-rays or bronchoscopy would be employed to check for evidence of pneumonia.
Treatment
So far, no antiviral therapy for HMPV has been proven to be effective. Only supportive and symptomatic care is provided alongside the management of likely complications:
Supportive Care
Rest, fluid intake, and over-the-counter medications for control of fever and body aches are given.
Oxygen Therapy
In cases of serious respiratory distress, supplemental oxygen can be given to the patients.
Hospitalization
Patients with severe infections, especially those at high risk, should be admitted and closely followed up with extensive supportive therapy.
Some of the interventions include Ribavirin and IVIG. These have been tried on immunocompromised patients, although with some severities, no one of them has been successful enough.
Complications
Most infections are mild, but the availability of some of the risk factors necessitates complications for the affected clients.
- Pneumonia: There will be viral pneumonia, which will require hospitalization and in severe cases, critical care.
- Airway Obstruction: It is associated with inflammation or obstruction of the smaller airways and is typically associated with hypoxia in infants and young children.
- The virus could lead to deterioration in case of chronic respiratory illnesses such as COPD, asthma and other diseases. Secondary bacterial infections such as pneumonia may complicate the patient’s condition. It mostly occurs as a consequence of an overactive immune response.
- HMPV could prove to be fatal for maternal and fetal health if associated with pregnancy.
Preventive measures to contain the spread of HMPV:
Hand hygiene, namely washing with soap and water at the right times.
- Respiratory etiquette: Cover nose and mouth with tissue or elbow when coughing or sneezing to reduce droplet spread.
- The virus would have been contained more effectively if intimate contact with persons showing respiratory symptoms had been shunned.
- Disinfection: The disinfections of the frequently contacted surfaces prevent the possibility of a fomite-borne illness.
- Stay Home Sick: The persons who manifest symptoms should stay home and not pass the virus around further.
Unavailability of Vaccine
No licensed vaccine has been developed for HMPV. It is still under study with several vaccine candidates in clinical trials, such as Moderna messenger RNA—modRNA vaccine with phase I clinical study for metapneumovirus. No generally available effective vaccines are available as of now.
Conclusion
HMPV remains one of the most probable aetiology of respiratory illnesses among other risk groups. Keeping a thorough knowledge of its clinical manifestations, diagnostic ways, methods to treat and possible risks would help cure the disease Efficiently. So far, studies are still on to develop vaccines; they might be more effective in preventing diseases when due time arrives.