Human metapneumovirus infection   02/12/24

Human metapneumoviruses cause upper respiratory tract infections (rhinitis, pharyngitis, sinusitis) to lower respiratory tract infections (bronchitis, bronchiolitis, pneumonia) in all age groups. The majority of cases are presumed to be upper respiratory tract infections, but lower respiratory tract infections are more common in infants and the elderly.
The incubation period is 4 to 6 days, viral load is high 1 to 4 days after fever, and viral excretion continues for 1 to 2 weeks. However, since many patients have mild disease, it is difficult to control the spread of infection by testing, and antigen testing should not be performed blindly on children with mild disease in order to prevent epidemics.
Since there are no antiviral drugs available, treatment is symptomatic and depends on the severity of symptoms, and testing does not change the course of treatment.
In cases of secondary bacterial infections, antibiotics should be used, and in children with bronchial asthma, treatment of the asthma will be necessary.
Lower respiratory tract inflammatory symptoms, such as a fever that lasts about 5 days like the flu and respiratory symptoms like RS virus infection, may occur together.
First infection begins at 6 months of age, 50% at 2 years of age, 75% at 5 years of age, and once by 10 years of age at the latest, but a single infection does not confer lifelong immunity, and re-infection occurs over and over.
Severe cases are more common in infants over 1 year of age, although RS virus is more common in infants under 6 months of age.
Epidemics occur from February to June after the influenza pandemic, often peaking in March and April.