Respiratory syncytial virus

Human respiratory syncytial virus is antigenycally stable virus which causes a serious respiratory diseases to humans. It belongs to the RNA-enveloped viruses in the familia Paramyxoviridae, subfamilia Pneumovirinae, genus Pneumovirus. The infection is worldwide spread and affects mainly infants and young children. During the replication of the virus, multinucleated syncytia are developed.

Pathogenesis
It is a common cause of severe respiratory infections in pediatrics, especially for preschool children, which causesbronchitis, bronchiolitis a pneumonia. The infection is spread by droplets( air-borne infection). It primary replicates in the air-passage mucosa cells. From there it is spread, especially during primary infection further to paranasal sinuses, Eustachian tube, middle ear and to lower respiratory tract. Mucosa responds to virus replication by development of edema, hypersecretion and necrosis of the epitelial cells, which can be secreted into the lumen. These factors can lead to bronchial and bronchioles obstruction and lungs atelectasis. Immunolgical protection against infection is provided by specific scretory IgA, maternal serum antibodies are not protective. With a decrease IgA the re-infection often occurs. It occurs inapparently in older children and adults or as a mild inflammation of the upper respiratory airways.

Clinical image
thumb|Newborn viral pneumonia caused by RSV Incubation time is 2—8 days. Then RSV infection can manifest as nasopharyngitis, bronchitis, bronchiolitis or pneumonia. The disease can be complicated by inflammation of the middle ear. In older children and adults, the disease is mild or the infection is completely inapparent. We have to expect a serious disease course in older patients and patients with immunodeficiency.

Therapy and prevention
Mild respiratory infections are treated symptomatically, for greater conditions with a severe course we apply ribavirin in aerosol. The use of inactivated vaccines has not been successful. Live-attenuated vaccines or recombinant are not available for wider use yet.

Immunoprophylaxis by palivizumab (specific monoclonal antibody against RSV) is used for immature newborns, a low birth weight infans and with bronchopulmonal dysplasia.

Video
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