Human metapneumovirus (hMPV) is a member of the genus Metapneumovirus, family Paramyxoviridae, and it belongs to the order Mononegavirales that is part of the negative single-stranded ribonucleic acid (RNA) virus, consisting of eight genes ordered: 3’-N-P-M-FM2-SH-G-L-5 ‘, and which encodes for 9 proteins. Usually causes mild respiratory illness. However, young children, the elderly, and people with immunodeficiency may develop severe complications, such as pneumonia, and require hospitalization.
Clinical characteristics: It is acquired through contact with respiratory secretions (e.g., sneezing, coughing, hands contaminated with secretions, etc.) of a sick person. Transmission occurs throughout the year with predominance in the winter, spring and summer months.
Respiratory syncytial virus (RSV) and hMPV cause similar symptoms. A runny nose and fever begin 3 to 7 days after infection. About half of children with a first infection also develop a cough and wheezing, rhinopharyngitis, congestion and/or nasal secretion discharge, indicating lower respiratory tract involvement. In infants younger than 6 months old, the first symptom may be a period of not breathing (apnea). In children, the infection often progresses to inflammation of the lower respiratory tract, causing bronchiolitis and pneumonia. In severe cases, it can induce asthma exacerbation, severe pneumonia, or acute respiratory distress syndrome. In adults, the symptoms are similar.
In healthy adults and older children, the illness is usually mild and may manifest only as a common cold.
Diagnosis: Diagnosis is made by medical evaluation. Doctors usually suspect a possibly hMPV infection in young infants and children who have bronchiolitis or pneumonia during RSV season or during an outbreak.
The objective of the diagnosis is to prevent in advance the possible appearance of complications related to human metapneumovirus, to differentiate from other viral or bacterial infections that do require specific treatment and to control transmission to healthy people.
Nasal discharge samples are evaluated by rapid antigen testing, PCR technique, or culture to help identify the virus.
Treatment: There is no available vaccine yet. The treatment at home is mainly for symptom relief. Children who have difficulty breathing are taken to a hospital. Depending on their condition, doctors may treat them with oxygen and fluids by vein.